Author Topic: Benzaldehyde + MEK acid catalyzed aldol  (Read 10303 times)

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viki

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gassing MEK
« Reply #20 on: November 06, 2003, 05:23:00 AM »
If one were scaling this reaction up would it work if  one were to gas say 3 litres of MEK first  a la Argox,  then add the MEK to the benzaldehyde say at a litre a time?Cheers Viki

bio

  • Guest
gassing MEK
« Reply #21 on: November 06, 2003, 07:23:00 PM »
Seems like it should work but I don't see the point here(storage maybe?) The gassing took me over 3 hours for a 360g MePhBuO in a 2 liter RB using an ice salt bath to keep the temp about 5 deg +/-. Then it would probably heat up again when you add to the PhCHO. Maybe a colder bath would speed it up if it wouldn't get too cold.

The left over MEK goes into the water wash. I was surprised to learn that MEK holds 24% water.......... To recycle do you know if distilling this MEK/HCL solution would damage the ketone?............. Or you could mix with the NaOH wash to neutralize as some is in there too. I only use AR chems and hate throwing it out but have been to busy to experiment with this idea. Also do a 1/2 vol sat salt wash to clear up the organic layer. This helps a lot.

Once you have some seeds the MePhBuO crystallizes nicely at room temp if properly distilled. It's instantaneous.

bio

  • Guest
The left over MEK goes into the water wash
« Reply #22 on: November 08, 2003, 03:07:00 AM »
Should have said a lot of it. You will get a small 74-84 deg fraction when distilling the MePhBuO (196ml of 750ml) in the last run. It is full of HCl even after washing with a 20% excess of lye.

chilly_willy

  • Guest
baeyer-villiger catalyst
« Reply #23 on: November 15, 2003, 04:06:00 AM »
I just finished searching at the library for possible baeyer-villiger catalysts and have come up with one that might seem promising.  Ferric chloride.  Would using this alone with H2O2 stirring like mad do the job any better? Yield-wise I mean.  What about adding it in with the perborate in twodogs original procedure.  I am still tryiing to understand the dynamics of the lewis-acid here so please correct me or point out why either suggestion will or wont work.  Thx...


Rhodium

  • Guest
I haven't memorized the entire literature
« Reply #24 on: November 15, 2003, 04:59:00 AM »
Post the procedures/references you have found, so that we have something to work with. It is a little hard to give critique on something we haven't read...

bio

  • Guest
baeyer-villiger catalysts
« Reply #25 on: November 15, 2003, 05:25:00 AM »
Would using this alone with H2O2 stirring like mad do the job any better?

The oxidation is done by the per acid; acetic in this case.

  What about adding it in with the perborate in twodogs original procedure.

This sounds feasible, would probably want the anhydrous ferric chloride as water is a product of the condensation. What molar proportions were used in the examples you found? I would think very little as FeCl3 is a good Friedel Crafts reactant, not quite as strong as Aluminum chloride which might also work.

bio

  • Guest
Perborate oxidations of ketones
« Reply #26 on: November 17, 2003, 11:55:00 PM »
SPC/SPB

Post 446838

(GC_MS: "SPC/SPB", Novel Discourse)
............Read this Chilly Willy and if you or anyone else has acess to

 Tetrahedron 1987,43,1753-1758

It is from the above article and is on room temp perborate oxidation of ketones to ketones in acetic acid at room temperature in good to excellent yields.

I'm still searching for a an oxidation catalyst to try and have seen MnSO4 a couple times in .01-.1 molar ratio but it's not clear if this won't also oxidise the ketone itself.

bio

  • Guest
Benzaldehyde + MEK acid catalyzed aldol
« Reply #27 on: November 24, 2003, 11:24:00 PM »
I don't have a lot of time to spend on this so if anyone sees any obvious boo boos please let me know. Just trying to repay my debt to the Hive. And clear my bad karma, how the hell did that happen?

Results of latest twodogs reaction.

1) Methyl Phenyl Butanone (MePhBuO)...... 400g PhCHO and 600g MEK (both RA grade) were mixed in a 2L flask placed in an ice salt bath and cooled to -5 degrees. 80 grams of DRY HCL gas was passed over about 3 hours keeping the temp below 5-7 degrees. Stirring with the thermometer. (This is about a 1 to 2.2 mole ratio as given by twodogs. Rhodium has posted an apparent improvement of yield to 94% with 1 to 1 mole which has not been tried yet.) A saturated solution is what is strived for here. Previous results indicated about 85% of the calculated HCl was absorbed. An additional 15% was partly added to compensate and the solution was saturated before it was all added. Flask stoppered and left in bath to warm up overnight ca. 10 hours. The Vogel  method of dripping 37% HCl into 98% H2SO4 was used with a H2SO4 dryer. Trap also used but not needed this time. Vogel says 31-33g HCl per 100ml.

2) The resulting deep reddish brown reaction mix was washed with an equal volume of water separated then washed with a 20% excess of 10% NaOH separated then washed with 1/2 volume of brine separated and filtered to give 845ml Ph 7-8 solution. This was distilled at atmospheric collecting most of the first fraction 74-84 degrees PH1 and the second fraction at aspirator pressure most was collected 119-140 degrees. MePhBuO clear yellow fruity smelling oil 506.7 gram includes the forerun and after run. This was allowed to cool to ambient, then seeded causing immediate crystalization. Let set up in frig with stirring for a couple hours. Filter on buchner wash with 95% EtOH dried for 430 grams total very clean and dry light yellow (almost white) pleasant smelling crystals. These initially set up as long  transparent light yellow needles. Happy now as had expected only 360 grams. Even returned to the vac dessicator to insure they were dry. Recrys of a little test resulted in very little improvement. This stuff is easy to crys in a relatively pure form. No GC/MS sorry.

3) Baeyer-Villiger Oxidation....... To a 6 liter FB flask on the mag stirrer hotplate in a water bath was added 2.3L Glacial Acetic Acid (RA) 615g NaPerborate 4H2O and 430g MePhBuO with stirring. This starts endothermic and mag stirring is inadequate until heat is added and the stuff dissolves. Added the crystals over ca. 1/2 hour while heating to about 45 deg. After the induction period added ice and or heating periodically to keep the solution temp 55-65 deg.  Can get into this more later if anyone actually is ready to do it. Stir vigorously keeping the temp as above for 6 hours. If it gets hotter as long as controllable it's OK. Be very carefull here I already had a near runaway........ Proceed slowly and carefully........ Cool to ambient then either dilute with water or recover the NaBO2 and acid first. Now extract with toluene or DCM. I used DCM this time and wish I didn't. Anyway extracted with 1.2L DCM washed with water and brine then removed solvent to leave the enol ester.

4) Hydrolysis and P2P...... enol ester added to 2.25L 10% NaOH in 50/50 w/w EtOH/H2O and stirred 2 hours. Extracted with DCM 300/200/200ml (again wish I had used PhMe) washed with water and brine removed solvent and collected 162g P2P at aspirator pressure (almost all between 119-140 deg).     OVER

bio

  • Guest
collected 162g P2P
« Reply #28 on: November 25, 2003, 01:02:00 AM »
correction......collected 169.5g...... did not drain completely...takes time you know

twodogs

  • Guest
Benzaldehyde + MEK acid catalyzed aldol
« Reply #29 on: November 25, 2003, 11:20:00 AM »
Nicely done Bio. One thing that should be mentioned is that in the condensation step, over gassing leads to some sort of polymerisation...evidently. There is a paper mentioning this somewhere. This is why I stated the weight of dry HCl in my original post of the set of reactions instead of just saying gas the shit out of it.

bio

  • Guest
polymerization
« Reply #30 on: November 25, 2003, 07:36:00 PM »
Well there is certainly a lot of the tarry polymer created using the 1 to ca.2 mole ratio. Perhaps going slower this time and watching temp more carefully and not taking out of the ice right away helped the yield. Also there could be a clue hidden in the reference to the gassing procedure (not given) which is the key to the 94% yield with only a trace of tar.  The statement regarding saturation was gleaned from the JACS 65,1824(1943) article Rhodium posted. I did notice that following your weights of HCL that saturation (or somewhere close) was reached very near the end. What was not stated in the synthesis part was the procedure or temp used when HCL gasing. There is a footnote to this article saying they followed this procedure.,,,,,,,,,,,(5) Muller and Harries, Ber., 36, 9BG (1902).,,,,,,,,,,,,if anyone could find this it would be very helpfull.

Surely somebee has access to Ber. (berliner I think) and could dig it up to assist.

psychokitty

  • Guest
Making this reaction more OTC . . .
« Reply #31 on: October 11, 2004, 08:41:00 AM »
I think the value of the following patent speaks for itself. If it's already been posted before, please accept my apologies in advance.  I tried to use TFSE.

( 1 of 1 )
United States Patent    4,673,766
Buck ,   et al.    June 16, 1987
Method of producing benzaldehyde

Abstract

A method is disclosed for producing benzaldehyde by fractionally steam distilling benzaldehyde from cinnamaldehyde in the presence of hydroxide catalyst and at a pH on the order of about 11 to about 13. Conversions of cinnamaldehyde to benzaldehyde can be achieved on the order of about 75% or more.
Inventors:    Buck; Keith T. (Cincinnati, OH); Boeing; Anthony J. (Cincinnati, OH); Dolfini; Joseph E. (Cincinnati, OH)
Assignee:    Mallinckrodt, Inc. (St. Louis, MO)
Appl. No.:    856595
Filed:    April 25, 1986

Current U.S. Class:    568/433; 568/458
Intern'l Class:    C07C 045/51
Field of Search:    568/433,458
References Cited [Referenced By]

Other References

Guthrie et al., Can. Jour. Chem., vol. 62 (1984), 1441-1445.

Primary Examiner: Helfin; Bernard
Attorney, Agent or Firm: Wood, Herron & Evans
Claims


What is claimed is:

1. A method of making benzaldehyde com- prising

dispersing cinnamaldehyde in water,

converting the cinnamaldehyde to benzaldehyde under the action of heat in the presence of a catalytic amount of hydroxide ion and at a pH of about 11 to about 13,

fractionally steam distilling benzaldehyde and acetaldehyde from the cinnamaldehyde, and

recovering benzaldehyde from the distillate.

2. The method of claim 1 which is conducted at a pH in the range of about 12 to about 12.5.

3. The method of claim 1 wherein the benzaldehyde distillate resulting from the steam distillation is fractionally distilled for separation of the benzaldehyde in substantially pure form.

4. The method of claim 1 wherein the acetaldehyde is vaporized during the course of the conversion while the benzaldehyde is condensed.

5. The method of claim 1 conducted in the presence of an anionic surfactant.

6. The method of claim 1 conducted under shearing agitation to facilitate the dispersion of the cinnamaldehyde in the water.

7. A method of making benzaldehyde com- prising

dispersing cinnamaldehyde in water in the presence of an anionic surfactant,

agitating the dispersion under the action of heat in the presence of a catalytic amount of hydroxide ion and at a pH of about 12 to about 12.5 for the conversion of cinnamaldehyde to benzaldehyde,

fractionally steam distilling benzaldehyde and acetaldehyde from the cinnamaldehyde in a still having a pot temperature of about 105.degree. C. and a column temperature of about 99.degree. C., and

fractionally distilling the benzaldehyde from the distillate for the separation of substantially pure benzaldehyde to obtain a yield of at least about 75% based upon the cinnamaldehyde.

8. The method of claim 7 wherein cassia oil is employed as a natural source for the cinnamaldehyde employed in the conversion.
Description


BACKGROUND OF THE INVENTION

The retroaldol reaction of cinnamaldehyde is well known. In this reaction, cinnamaldehyde is converted to benzaldehyde and acetaldehyde with various potential side reactions. Recently, for example, an investigation of the kinetics of the retroaldol reaction of cinnamaldehyde has been reported by J. Peter Guthrie, et al, Can. J. Chem., Vol. 62, pp. 1441-1445 (1984). While the conversion of the cinnamaldehyde to benzaldehyde has been long known and well studied, it has not been heretofore known to produce benzaldehyde from cinnamaldehyde in substantial yields and favorable reaction conditions for production of such yields have not been reported.

SUMMARY OF THE INVENTION

This invention is directed to a method of making benzaldehyde by conversion of cinnamaldehyde in the presence of water with surprisingly high yields heretofore unachieved. The invention involves the dispersion of cinnamaldehyde in water and, in the presence of an effective catalytic amount of hydroxide ion, fractionally steam distilling benzaldehyde from the cinnamaldehyde. The reaction is conducted at a pH on the order of about 11 to about 13 and, unexpectedly, within this pH range it has been discovered that a substantial conversion of cinnamaldehyde to benzaldehyde can be achieved on the order of about 75% or more. It has also been found that the conversion may be achieved at such a high pH without adverse side reactions.

In a preferred mode of conducting the method, the cinnamaldehyde is dispersed in the water in the presence of shearing agitation and a surfactant. In another aspect of this invention, it is preferred to employ an anionic surfactant such as sodium lauryl sulfate. Preferably, the hydroxide ion is furnished by means of sodium hydroxide which also achieves the pH in the range of about 11 to about 13. It has critically been determined that the fractional steam distillation of benzaldehyde from the cinnamaldehyde must be conducted at a pH within the range of about 11 to about 13, preferably about 12 to about 12.5. Below and above this pH range, very poor conversions are obtained of 50% or far less and competing reactions interfere with the production of benzaldehyde. Outside of this critical pH range, side reactions, polymerization and other adverse reactions prohibit any significant yield of benzaldehyde. Yet, within the pH range of about 11 to about 13, especially about 12 to about 12.5, significant yields on the order of 75% or greater are achieved and benzaldehyde is recoverable in substantially pure form free of side reaction products. These results are considered to be unexpected especially at the high pHs of the reaction where it may have been expected that side reactions would have significantly lessened or prevented the yield for the desired product.

During the course of the fractional steam distillation of benzaldehyde from the cinnamaldehyde, acetaldehyde is also vaporized and removed. The removal of acetaldehyde thus prevents the forward polymerization reaction which otherwise competes in the presence of the catalyst. The benzaldehyde which has been steam distilled is then subsequently fractionally distilled for separation of the benzaldehyde from other components in the distillate such as minor amounts of acetaldehyde, terpenes and orthomethoxybenzaldehyde. It has also been found that a natural source for the cinnamaldehyde such as cassia oil may be employed containing a substantial amount of the natural cinnamaldehyde. Thus, a natural product such as cassia oil may be employed in the fractional steam distillation method of this invention and still the significant yields on the order of about 75% or more are achieved.

DETAILED DESCRIPTION

The following detailed operating example illustrates the practice of the invention in its most preferred form, thereby enabling a person of ordinary skill in the art to practice the invention. The principles of this invention, its operating parameters and other obvious modifications thereof will be understood in view of the following detailed procedure.

OPERATING EXAMPLE

A solution was made up from 38.6 lbs. sodium hydroxide, 4 lbs. sodium lauryl sulfate and 10 liters antifoam agent in 760 gallons of water. The solution was stirred until a homogeneous solution was obtained. Then, 1320 lbs. of cassia oil were placed in a 1150 gallon still. The oil contained approximately 72% by weight of cinnamaldehyde. The still had a pot volume of about 1150 gallons onto which was mounted a 4 foot fractionating column containing 1".times.1" ceramic tubes and a water cooled condenser was thereafter connected in series for condensing the benzaldehyde-water azeotrope.

The above prepared sodium hydroxide solution was then added to the cassia oil and introduced into the pot of the still. The pot was equipped with a stirrer. Using pressurized steam and vigorous stirring, the pot was heated to reflux with a pot temperature of 105.degree. C. Reflux was established with a column head temperature of about 99.degree. C. Once reflux was established, it was continued for about 1 hour. During the course of the conversion of the cinnamaldehyde in the cassia oil to benzaldehyde, pH was monitored and was maintained at about 12 to about 12.5. In the event the pH fell below about 12, sodium hydroxide was added to bring the pH back up to the range of about 12-12.5. After refluxing for about 1 hour, take-off of the water-benzaldehyde azeotrope was initiated. The water cooled condenser was operated at 100.degree. F. thereby enabling the water-benzaldehyde azeotrope to be condensed and collected in a chilled receiver. The acetaldehyde by-product was principally vaporized at the temperature of the condenser and was taken off as vapor. The distillate principally containing benzaldehyde in an amount of about 75% or more with minor amounts of cinnamaldehyde, terpenes, orthomethoxybenzaldehyde and acetaldehyde was obtained. The crude benzaldehyde was thus collected in a chilled receiver and, in a continuous feed operation the condensed water was continuously fed back to the still to replace what had been taken off and the distillation of the azeotrope continued. The fractional steam distillation of the crude benzaldehyde continued until about 670 lbs. of crude benzaldehyde were obtained. The crude distillate containing benzaldehyde was then dried under vacuum and fractionally distilled under vacuum of about 29" thereby providing a boiling point for the benzaldehyde at about 70.degree. C. in order to obtain a substantially pure benzaldehyde free from residual terpenes and other impurities.

Thus, by means of practicing the above process, the objectives of this invention are achieved in that cinnamaldehyde is converted into benzaldehyde in substantially pure form even from the natural source of cassia oil. Surprisingly, it has been found that substantial yields in excess of 75% or more of substantially pure benzaldehyde are achieved by this method. Moreover, it has been found that there is a surprising window of high pH at which the conversion may take place in a fractional steam distillation column in order to separate the benzaldehyde and acetaldehyde from the reaction mixture and still avoid the adverse side reactions from occurring.

Having described this invention and its operating parameters, variations may be achieved without departing from the spirit and scope hereof.

psychokitty

  • Guest
The surprises never end, do they? . . .
« Reply #32 on: October 11, 2004, 08:45:00 AM »
And here's yet another good and useful patent:

 ( 1 of 1 )
United States Patent    4,766,249
Buck ,   et al.    * August 23, 1988
Method of catalytically hydrolyzing alpha, beta-unsaturated carbonyl compounds

Abstract

Alpha, beta-unsaturated carbonyl compounds are hydrolyzed under alkaline conditions in the presence of water to produce additional carbonyl-containing compounds. High yields are obtained when the alkaline catalyst contains hydroxide ion and the pH is maintained in the range of about 11 to about 13.
Inventors:    Buck; Keith T. (Cincinnati, OH); Boeing; Anthony J. (Cincinnati, OH); Dolfini; Joseph E. (Cincinnati, OH); Glinka; Jerome (Cincinnati, OH)
Assignee:    Mallinckrodt, Inc. (St. Louis, MO)
  • Notice:    The portion of the term of this patent subsequent to June 16, 2004 has been disclaimed.
Appl. No.:    942491
Filed:    December 24, 1986

Current U.S. Class:    568/433; 568/458
Intern'l Class:    C07C 045/42
Field of Search:    568/426,433,435,437,440,458
References Cited [Referenced By]

Other References

Guthrie et al., "Can. J. Chem.", vol. 62, pp. 1441-1445, (1984).

Primary Examiner: Lone; Werren B.
Attorney, Agent or Firm: Wood, Herron & Evans
Parent Case Text


RELATED APPLICATION

This is a continuation-in-part of application Ser. No. 856,595, filed Apr. 25, 1986, invented by Keith T. Buck, Anthony J. Boeing and Joseph E. Dolfini, and assigned to the assignee of this application, now U.S. Pat. No. 4,673,766.
Claims


What is claimed is:

1. A method of producing a carbonyl-containing compound which comprises

hydrolyzing by dispersing in water an alpha, beta-unsaturated carbonyl compound of the formula ##STR3## to produce a carbonyl-containing compound and by-product according to the following formulas ##STR4## wherein R' and R" are hydrogen, aliphatic or aromatic hydrocarbon groups or substituted derivatives thereof, and R"' is an aliphatic or aromatic aldehyde- or ketone-containing group having the carbon to oxygen double bond of said aldehyde or ketone conjugated with the alpha, beta double bond between C and R"' of alpha, beta-unsaturated alpha,beta-unsaturated carbonyl compound, and

conducting said hydrolysis of the alpha, beta-unsaturated carbonyl compound under the action of heat in the presence of a catalytic amount of hydroxide ion and at a pH of about 11 to about 13.

2. The method of claim 1 which is conducted at a pH in the range of about 12 to about 12.5.

3. The method of claim 1 wherein the individual carbonyl-containing compounds obtained from said hydrolysis reaction are fractionally distilled for separation in substantially pure form.

4. The method of claim 1 conducted in the presence of an anionic or non-ionic surfactant.

5. The method of claim 1 conducted under shearing agitation to facilitate the dispersion of the alpha, beta-unsaturated carbonyl compound in the water.

6. The method of claim 1 wherein said alpha, beta-unsaturated carbonyl compound is citral and the carbonyl-containing compounds produced are 6-methyl-5-hepten-2-one and acetaldehyde.

7. The method of claim 1 wherein said alpha, beta-unsaturated carbonyl compound is pulegone and the carbonyl-containing compounds produced are acetone and 3-methylcyclohexanone.

8. A method of producing a carbonyl-containing compound which comprises

hydrolyzing by dispersing in water under shearing agitation in the presence of an anionic surfactant an alpha, beta-unsaturated carbonyl compound of the formula ##STR5## to produce a carbonyl-containing compound and by-product according to the following formulas ##STR6## wherein R' and R" are hydrogen, aliphatic or aromatic hydrocarbon groups or substituted derivatives thereof, and R"' is an aliphatic or aromatic aldehyde- or ketone-containing group having the carbon to oxygen double bond of said aldehyde or ketone conjugated with the alpha, beta double bond between C and R"' of said alpha, beta-unsaturated carbonyl compound, and

conducting said hydrolysis of the alpha, beta-unsaturated carbonyl compound under the action of heat in the presence of a catalytic amount of hydroxide ion and at a pH of about 12 to about 12.5.
Description


BACKGROUND OF THE INVENTION

The retroaldol reaction of cinnamaldehyde is well known. In this reaction, cinnamaldehyde is converted to benzaldehyde and acetaldehyde with various potential side reactions. Recently, for example, an investigation of the kinetics of the retroaldol reaction of cinnamaldehyde has been reported by J. Peter Guthrie, et al, Can. J. Chem., Vol. 62, pp. 1441-1445 (1984). The conversion of the cinnamaldehyde to benzaldehyde has been long known and well studied. However, it has not been heretofore known to produce benzaldehyde from cinnamaldehyde in substantial yields, and favorable reaction conditions for production of such yields have not been reported. Similarly, citral has been hydrolyzed via the retroaldol reaction to produce 6-methyl-5-hepten-2-one and acetaldehyde. Again, however, product yield is low. Up to now, it has not been known how to obtain carbonyl-containing reaction products in substantial yields through the retroaldol hydrolysis of any of the alpha,beta-unsaturated carbonyl compounds, of which cinnamaldehyde and citral are examples.

SUMMARY OF THE INVENTION

The invention disclosed in the above application Ser. No. 856,595 is directed to a method of making benzaldehyde by conversion of cinnamaldehyde in the presence of water with surprisingly high yields heretofore unachieved. The invention involved the dispersion of cinnamaldehyde in water and, in the presence of an effective catalytic amount of hydroxide ion, fractionally steam distilling benzaldehyde from the cinnamaldehyde. The reaction was conducted at a pH on the order of about 11 to about B 13 and, unexpectedly, within this pH range it has been discovered that a substantial conversion of cinnamaldehyde to benzaldehyde could be achieved on the order of about 75% or more. It has also been found that the conversion may be achieved at such a high pH without adverse side reaction.

It has also been found that members of the class of compounds known as alpha,beta-unsaturated carbonyl compounds, of which cinnamaldehyde is an example, can be hydrolyzed via the retroaldol reaction to produce carbonyl-containing compounds in substantial yields.

In a preferred mode of conducting the method, the alpha,beta-unsaturated carbonyl compound is dispersed in water in the presence of shearing agitation. It will be understood that other water soluble or dispersible cosolvents such as alcohols, ethers or the like may be used in the aqueous reaction medium. An anionic surfactant such as sodium lauryl sulfate or a non-ionic surfactant such as polyethylene glycol having a molecular weight in the range of 400 to 600 may be used. Preferably, the hydroxide ion is furnished by means of sodium hydroxide which also achieves a pH in the range of about 11 to about 13. After the starting materials have been charged to the flask, reaction is initiated with the addition of heat. Once reaction has begun, separation of the products is achieved through the production of water-product azeotropes which are isolated by fractional distillation. It has been critically determined that the fractional distillation must be conducted at a pH within the range of about 11 to about 13, preferably about 12 to about 12.5. Reactions conducted outside this pH range exhibit very poor conversion to desired product because side reactions, polymerization and other adverse reactions occur.

Reactions conducted within the pH range of about 11 to about 13, and especially between about 12 and about 12.5, produce significant yields on the order of 75% or greater and are substantially free of side reaction products. These results are considered to be unexpected especially at the high pH levels of the reaction where it may have been expected that side reactions would have significantly lessened or prevented the yield for the desired product.

The reaction products isolated by fractional distillation may be further purified by means of additional separation techniques. The separation technique employed may vary with the degree of purity sought. Pure alpha,beta-unsaturated carbonyl compounds may be used as starting materials for the reaction. However, product yield percentage is not adversely affected when natural products containing the desired starting materials are used in the reaction. Thus, a natural product such as cassia oil containing substantial amounts of cinnamaldehyde may be used successfully in this invention. Similarly, lemon grass oil containing citral may be used successfully. Also, pennyroyal oil may be utilized under the teachings of this invention as a source of pulegone, an alpha,beta-unsaturated carbonyl compound.

DETAILED DESCRIPTION

The method in its broader aspects is practiced by hydrolyzing after dispersing in water an alpha,beta-unsaturated carbonyl compound having the formula ##STR1## to produce a carbonyl-containing compound and a by-product having the general formulas ##STR2## The substituents R' and R" are hydrogen, aliphatic or aromatic hydrocarbon groups or substituted derivatives thereof, and R"' is an aliphatic or aromatic aldehyde- or ketone-containing group having the carbon to oxygen double bond of the aldehyde or ketone conjugated with the alpha,beta double bond between C and R"' of the alpha,beta-unsaturated carbonyl compound. The hydrolysis reaction proceeds under the action of heat and is catalyzed by hydroxide ion having a concentration level sufficient to maintain the solution pH between about 11 and about 13.

A large number of alpha,beta-unsaturated carbonyl compounds may be hydrolyzed according to the teachings of this invention. The compounds in the following non-comprehensive list are included under the description of hydrolyzable alpha,beta-unsaturated carbonyl compounds: cinnamaldehyde to produce benzaldehyde and acetaldehyde; citral to produce 6-methyl-5-hepten-2-one and acetaldehyde; pulegone to produce 3-methylcyclohexanone and acetone; 3-decen-2-one to produce heptanal and acetone; 2-dodecenal to produce decanal and acetaldehyde; 2-heptenal to produce pentanal and acetaldehyde; 2-hexenal to produce butanal and acetaldehyde; ionone to produce cyclocitral and acetone; irone to produce 2,5,6,6-tetramethyl-cyclohex-1-ene-1-carboxaldehyde and acetone; 1-(4-methoxyphenyl)-1-penten-3-one to produce paramethoxybenzaldehyde and methyl ethyl ketone; 5-methyl-3-hexen-2-one to produce isobutyraldehyde and acetone; alpha-methyl-iso-ionone to produce citral and methyl ethyl ketone; 5-methyl-2-phenyl-2-hexenal to produce phenyl acetaldehyde and 3-methylbutanal; 4-phenyl-3-buten-2-one to produce benzaldehyde and acetone; and ortho-methoxy cinnamaldehyde to produce ortho-methoxy benzaldehyde and acetaldehyde.

(to be continued . . .)

psychokitty

  • Guest
Continued from above . . .
« Reply #33 on: October 11, 2004, 08:47:00 AM »
OPERATING EXAMPLE I

A solution was made up from 38.6 lbs. sodium hydroxide, 4 lbs. sodium lauryl sulfate and 10 liters antifoam agent in 760 gallons of water. The solution was stirred until a homogeneous solution was obtained. Then, 1320 lbs. of cassia oil were placed in a 1150 gallon still. The oil contained approximately 72% by weight of cinnamaldehyde. The still had a pot volume of about 1150 gallons onto which was mounted a 4 foot fractionating column containing 1".times.1" ceramic tubes and a water-cooled condenser was thereafter connected in series for condensing the benzaldehyde-water azeotrope.

The above prepared sodium hydroxide solution was then added to the cassia oil and introduced into the pot of the still. The pot was equipped with a stirrer. Using pressurized steam and vigorous stirring, the pot was heated to reflux with a pot temperature of 105.degree. C. Reflux was established with a column head temperature of about 99.degree. C. Once reflux was established, it was continued for about 1 hour. During the course of the conversion of the cinnamaldehyde in the cassia oil to benzaldehyde, pH was monitored and was maintained at about 12 to about 12.5. In the event the pH fell below about 12, sodium hydroxide was added to bring the pH back up to the range of about 12-12.5. After refluxing for about 1 hour, take-off of the water-benzaldehyde azeotrope was initiated. The water-cooled condenser was operated at 100.degree. F. thereby enabling the water-benzaldehyde azeotrope to be condensed and collected in a chilled receiver. The acetaldehyde by-product was principally vaporized at the temperature of the condenser and was taken off as vapor. The distillate consisted principally of benzaldehyde in an amount of about 75% or more with minor amounts of cinnamaldehyde, terpenes, orthomethoxybenzaldehyde and acetaldehyde. The crude benzaldehyde was thus collected in a chilled receiver and, in a continuous feed operation the condensed water was continuously fed back to the still to replace what had been taken off and the distillation of the azeotrope continued. The fractional steam distillation of the crude benzaldehyde continued until about 670 lbs. of crude benzaldehyde was obtained. The crude distillate containing benzaldehyde was then dried under vacuum and fractionally distilled under vacuum of about 29" thereby providing a boiling point for the benzaldehyde at about 70.degree. C. in order to obtain a substantially pure benzaldehyde free from residual terpenes and other impurities.

OPERATING EXAMPLE II

Into a 5-liter, 3-neck flask was charged 1012.5 g of pennyroyal oil, containing a substantial portion of pulegone, 3.5 liters water and 30 g sodium hydroxide having a minimum 90% purity. The initial charge of hydroxide produced a pH of about 12. The pH was monitored during the subsequent reaction, and additional sodium hydroxide was added as needed to maintain a pH of about 12. The flask was equipped with a mechanical stirrer/drive motor apparatus and a fractionating column. After agitation was initiated, heat was applied to the mixture in the flask by means of a heating mantle.

As the agitated mixture of pennyroyal oil, sodium hydroxide and water was heated, the pressure in the flask was maintained at atmospheric by permitting the fractionating column to remain uncapped. At a pot temperature of approximately 100.degree. C. and a head temperature of approximately 56.degree. C., distillation occurs and an azeotropic mixture of 96% acetone and 4% water is collected off the top of the fractionating column. The azeotrope was collected by means of the fractionating column.

The co-distillation of acetone occurred over a period of about six days. Agitation and heating were discontinued when no additional distillate was generated. The oil layer remaining in the flask was separated from the sodium hydroxide solution and then water-washed to remove traces of sodium hydroxide.

The washed oil contained the hydrolysis product 3-methylcyclohexanone (b.p. 168.degree.-9.degree. C.), minor amounts of unhydrolyzed pulegone (b.p. 224.degree. C.), and other trace components attributable to the starting pennyroyal oil. The acetone was subsequently assayed for purity, including a determination of water content. The yield of acetone was approximately 73%.

OPERATING EXAMPLE III

Approximately 500 ml water, 5 g (90% active) sodium hydroxide, and 88 g terpeneless lemon grass oil containing approximately 95% citral were charged into a one-liter round bottom flask. The round bottom flask was equipped additionally with a trap having means of permitting removal of the lower density liquid while recirculating the higher density liquid, a fractionating column, and a means for stirring.

The stirred contents of the flask were heated to reflux by means of a heating mantle. The pH of the contents was set at 12 and maintained at that level during the remainder of the run by addition of sodium hydroxide when necessary. The contents were refluxed for one hour, after which time the steam distillate was slowly collected. The distillate take-off was regulated so that little or no citral distilled over. The distillation was continued until no additional oil was collected.

The oil phase distillate was separated from the steam condensate. The separated oil was then short-path vacuum distilled. The main cut yielded 72 g of the citral hydrolysis product, 6-methyl-5-hepten-2-one. The other reaction product, acetaldehyde, was vented from the flask through the fractionating column during the reaction. The yield of 6-methyl-5-hepten-2-one was approximately 90% under the above conditions.

Thus, by means of practicing the preferred processes listed above, the objectives of this invention are achieved in that desirable products can be obtained in good yield from alpha,beta-unsaturated carbonyl compounds. Pure starting materials may be used, but good results are obtainable even from natural sources of the alpha,beta-unsaturated carbonyl compounds. It is critical to the teachings of this invention that reaction take place in an alkaline hydroxide environment wherein the pH is maintained within a window of about 11 to about 13. Unexpectedly, not only are products obtained in yields exceeding 70 to 75%, but the reaction proceeds with a low level of competitive side reactions, polymerization or other adverse reactions.

Having described this invention and its operating parameters, variations may be achieved without departing from the spirit and scope hereof.

psychokitty

  • Guest
Another retroaldol cleavage of cinnamaldehyde?
« Reply #34 on: October 12, 2004, 01:05:00 AM »
Here's another way to get benzaldehyde using a variation of the retroaldol reaction.  4-Phenyl-3-buten-2-one is oxidized to the epoxide via basic H2O2 and then cleaved by the NaOH to benzaldehyde and acetone.  The yields are supposedly higher that the then-utilized base-catalyzed "retrograde aldol reaction" (retroaldol reaction) and the products of the reaction appear to be cleaner.  All in all, the method seems pretty simple and just as OTC as the aforementioned retroaldol reaction using cinnamaldehyde as a precursor to benzaldehyde.

The Epoxidation and Cleavage of a,B-Unsaturated Ketones with Alkaline Hydrogen Peroxide
ROBERT D. TEMPLE
The Journal of Organic Chemistry Vol. 35, No. 6, May 1970



Abstract:

The kinetics of the reaction between 4-phenyl-3-buten-2-one and aqueous alkaline hydrogen peroxide were studied. Four reactions occur in this system : epoxidation by hydroperoxide ion to form 4-phenyl-3,4-epoxy-2-butanone, oxidative cleavage of the epoxide by hydroperoxide to give benzaldehyde, retrograde aldol reaction,and cleavage of the epoxide by hydroxide. The rates of these reactions in water at 25” are 0.22,0.05,0.00016,and 0.0032 1. mol-’ sec-l, respectively. The influence of substituents in the phenyl ring on reaction rates and the relative reactivities of hydroperoxide and hydroxide ions are discussed in terms of the reaction mechanisms. The oxidative cleavage of a,p-epoxy ketones is mechanistically similar to several recently reported fragmentation reactions. The cleavage reaction was shown to have general synthetic utility in preparing diacids, keto acids, and ketones from +-unsaturated ketones, alp-unsaturated aldehydes, and p diketones.

Preparative Oxidation Procedure:

To a solution of 0.01 mol of the a,B-unsaturated carbonyl compound in 50 ml of methanol,12 ml of 30% aqueous hydrogen peroxide and then 30 ml of 1 N aqueous sodium hydroxide solution were added with cooling. The mixture was then stirred overnight at 40-50" (1 hr at 40" for the reaction with citral). The resulting solution was evaporated to about half the original volume on a rotary evaporator and then washed with ether. The aqueous solution was made acidic with sulfuric acid, saturated with sodium sulfate, and extracted thoroughly with ether. The extract was treated with FeSO4 or Na2SO3 to destroy peroxides, dried (MgSO4), and evaporated. The residue, which was essentially pure product, was recrystallized, distilled, or converted into a suitable derivative as outlined below.

Note:  4-Phenyl-3-buten-2-one is not listed in the experimetal section of the article.

psychokitty

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Baeyer-Villiger reaction using Oxone as oxidant
« Reply #35 on: October 12, 2004, 02:11:00 AM »
Maybe this might work to effect a more OTC Baeyer-Villiger transformation.

Facile Oxidation of Aldehydes to Acids and Esters with Oxone
Benjamin R. Travis, Meenakshi Sivakumar, G. Olatunji Hollist, and Babak Borhan*
ORGANIC LETTERS 2003 Vol. 5, No. 7 1031-1034



Abstract:

A highly efficient, mild, and simple protocol is presented for the oxidation of aldehydes to carboxylic acids utilizing Oxone as the sole oxidant. Direct conversion of aldehydes in alcoholic solvents to their corresponding ester products is also reported. These reactions may prove to be valuable alternatives to traditional metal-mediated oxidations.

Description of the art:

As a fortuitous extension of the solvent study, the  oxidation of aldehydes with Oxone in alcoholic solvents cleanly provided high conversion to esters. Thus, the oxidation of benzaldehyde in methanol did not yield the expected carboxylic acid, but instead the methyl ester was obtained. The present strategy complements other known methods that directly convert aldehydes to esters such as oxidation in the presence of alcohol with Br2 or I2, NBS/AIBN, PDC, HCN/MnO2, or performed  electrochemically.21-25 Additionally, we found that other alcohols such as ethanol, n-propanol, and 2-propanol also provide their corresponding esters in excellent yields, although oxidation in tert-butyl alcohol furnished the carboxylic acid as the sole product (Table 3, entries 1-9). It is important to note that the esters are not obtained as the result of the oxidation of aldehydes to carboxylic acids followed by Fischer-type esterification of the acids in alcoholic solvents. Incubation of benzoic acid in methanol with Oxone for a prolonged period did not result in the isolation of methyl benzoate, but in fact the starting acid was re-isolated quantitatively.

The direct oxidation of a variety of aryl and alkyl aldehydes to their corresponding methyl esters is also illustrated in Table 3 (entries 10-19). Oxidation of aryl aldehydes with electron-withdrawing substituents showed slow conversion to the esters (Table 3, entries 10 and 11) initially providing dimethyl acetals in addition to the ester products. This was overcome by heating the reactions to reflux overnight, which provided clean conversion to the  desired methyl esters 1b and 2b. Oxidation of 6 and 9 (electroneutral aromatics aldehydes) and 19-23 (aliphatic aldehydes) proceeded smoothly at rt to furnish the desired methyl esters in excellent yields. In the case of electronrich aromatic substrates, as with the oxidations to carboxylic acids in DMF, the Dakin products were observed. thus, 4-hydroxybenzaldehyde, 12, and p-anisaldehyde, 13, provided primarily phenols 16 and 17 in 77% yield for both (Scheme 3), along with small amounts of the corresponding  sters (Table 3, entries 14 and 15). Additionally, oxidation of 27 provided 75% yield of the ç-ketomethyl ester product 30 (methyl ester of 29).

Noteworthy, is the fact that isopropyl esters are made with ease in high yields. However, as mentioned above, tert-butyl esters cannot be accessed, most probably due to the sterics of the bulky alcohol. Although at this time conversion of aldehydes to esters proceed best if the reaction is  performed in the alcoholic solvent (in order to circumvent the formation of carboxylic acids), studies are underway  with mixed solvents and show promising indications that the oxidation to carboxylic acids could be retarded in favor of esterification. Thus, it could be possible to lessen the  amounts of alcohol used in the oxidation.
 
Although any mechanistic discussion is speculative at this point, we believe that the oxidation proceeds via a Baeyer-Villiger process. As depicted in Scheme 4, the proposed intermediates in the oxidation of aldehydes to carboxylic acids and esters are mixed peroxyacetals A and B. Rearrangement of intermediates A and B would yield the  products by expelling bisulfate. Corroboration for the proposed mechanism is based on the well-understood oxidation of aldehydes to carboxylic acids with peroxyacids.26 Also, recently it has been demonstrated that acetals are oxidized to their corresponding esters with Oxone,10 and thus, intermediate B could be derived from either the hemiacetal or acetal (Scheme 4). It should be pointed out that Oxone is slightly acidic and, therefore, could catalyze the formation of the presumed peroxyacetals. Presently, mechanistic studies including use of 18O-labeled aldehydes and NMR experiments to observe transient intermediates are underway.

In conclusion, we have demonstrated a simple and effective one-pot protocol to oxidize aldehydes directly to acids or esters. These reactions are facile, high-yielding, and easy to work up (most do not require chromatography) and should provide a mild oxidative alternative for organic chemists. The mechanism of these transformations is being investigated and will be reported in due course.

Experimental: 

(A bit too simple.)

Aldehyde (1 equiv), Oxone (1 equiv), ROH (0.2 M), 18 h, rt.

bio

  • Guest
Baeyer-Villiger reaction recycling
« Reply #36 on: October 12, 2004, 08:37:00 AM »
Some nice articles you found psychokitty.

Assuming you have a basic understanding of the procedure of this thread (Rhodium posted some dwgs somewhere) I wanted to ask you if you have any input on the following:

In the patent twodogs cited where he got the idea of using perborate it states ......(paraphrased)near quantitative yields of the B/V product can be achieved in the oxidation by appropriate recycling..........

That's it no experimental, examples, discussion, nothing.
Will be making a few more runs with the MePhBuO soon and will try  some recycling ideas at small test scale. Ah.... so many reactions so little time...

Now I suppose that the simplest and easiest way to do this would be to simply filter, add more perborate and run it again. Maybe removing some water (dessicant) would be helpful. Hopefully the selectivity is such that the ketone enol ester would not be damaged. Another place would be after the isolation before the hydrolysis or even after the hydrolysis itself.

Any thoughts on this?????? I have various improvements on the overall procedure but nobody seems to be interested enough in this method (except one bee I know of) to
actually do it. So I don't waste my time but I do thank you and the Hive for all the great stuff, especially Rhodium for finding several of the key references for this and similar reactions.

psychokitty

  • Guest
United States Patent 4,988,825
« Reply #37 on: October 13, 2004, 07:28:00 AM »

In the patent twodogs cited where he got the idea of using perborate it states ......(paraphrased)near quantitative yields of the B/V product can be achieved in the oxidation by appropriate recycling..........

That's it no experimental, examples, discussion, nothing.
Will be making a few more runs with the MePhBuO soon and will try  some recycling ideas at small test scale. Ah.... so many reactions so little time...



Actually, the segment in the patent to which you refer goes like this:


The present invention provides a safe and economical process for oxidizing aldehydes and ketones using an alkali metal perborate, such as sodium perborate, as the oxidant. Alkali metal perborates are safe and economical to use, and the sodium borate by-product thus formed is safely handled and is a valuable product that can be sold in its own right. In addition, the oxidation is carried out under easily maintained reaction conditions and provides selectivities approaching 100% so that all of the starting aldehydes or ketones can be converted to final product by appropriate recycling. It can be seen that the use of the alkali metal perborate provides a substantial advance in the oxidation of aldehydes and ketones.



All the authors are trying to say is that because the use of sodium perborate is so exceptionally selective, there won't be any byproducts to the reaction, and whatever starting materials are left over--in this case, the intermediate aldol condensation product of benzaldhyde and MEK--can be reused in another sodium perborate Baeyer-Villiger reaction.

Anyway, that's my interpretation.  I could be wrong.

Here's the a text copy of the patent in question, for all those who would like to read it:

( 1 of 1 )
United States Patent    4,988,825
Bove    January 29, 1991
Oxidation of aldehydes and ketones using alkali metal perborates

Abstract

Aldehydes and ketones, other than acetone, are oxidized with an alkali metal perborate in the presence of an acid.
Inventors:    Bove; John L. (Ridgewood, NJ)
Assignee:    Cooper Union Research Foundation, Inc. (New York, NY)
Appl. No.:    910615
Filed:    September 23, 1986

Current U.S. Class:    549/272; 549/273; 549/295; 560/231; 562/528
Intern'l Class:    C07D 313/18; C07D 313/04
Field of Search:    549/272,273,295 562/528 560/231
References Cited [Referenced By]
U.S. Patent Documents
3122586   Feb., 1964   Berndt et al.    
3154586   Oct., 1964   Bander et al.    
3483222   Dec., 1969   Sennewald et al.    
3716563   Feb., 1973   Brunie et al.   549/524.
3833613   Sep., 1974   Field   549/272.
4160769   Jul., 1979   Higley.    
4213906   Jul., 1980   Mares et al.   549/272.
4286068   Aug., 1981   Mares et al.   549/272.
4338260   Jul., 1982   Schirmann   260/502.
Foreign Patent Documents
1096967   Dec., 1967   GB   549/272.


Other References

Y. Ogata et al., Bulletin of the Chemical Society of Japan, vol. 52(2), (1979), pp. 635-636.
A. Baeyer et al., Ber., 1899, 32, 3625-3633.
A. Baeyer et al., Ber., 1900, 33, 858-864.
Ogata et al., Chem. Abst. 90:167685, (1979).
McKillop et al., Tetrahedron Letters, 24, No. 14, (1983), 1505-1508.
McKillop et al., Tetrahedron, 43, pp. 1753-1758 (1987).
A. Rashid et al., J. Chem. Soc. (C) (1967), pp. 1323-1325.


Description

The present invention is directed to the oxidation of aldehydes and ketones to the corresponding acids and esters, respectively using an alkali metal perborate as the oxidant.

The oxidation of ketones, including cyclic ketones, to esters through the use of peracids is known as the Baeyer-Villager Reaction (A. Von Baeyer and V. Villager, Ber., 1899, 32, 3265; 1900, 33, 858) While widely applied, particularly for the oxidation of cyclohexanone to epsilon-caprolactone, nevertheless the use of a peracid presents problems of safety and disposal and/or recycling of organic compounds.

The present invention provides a safe and economical process for oxidizing aldehydes and ketones using an alkali metal perborate, such as sodium perborate, as the oxidant. Alkali metal perborates are safe and economical to use, and the sodium borate by-product thus formed is safely handled and is a valuable product that can be sold in its own right. In addition, the oxidation is carried out under easily maintained reaction conditions and provides selectivities approaching 100% so that all of the starting aldehydes or ketones can be converted to final product by appropriate recycling. It can be seen that the use of the alkali metal perborate provides a substantial advance in the oxidation of aldehydes and ketones.

In particular, the present invention provides a method of preparing acids or esters, which comprises oxidizing an aldehyde (other than acetone) or a ketone with an alkali metal perborate in the presence of an acid.

With the exception of acetone, the present invention is applicable to the oxidation of aldehydes and ketones to form the corresponding esters and/or acids. Aromatic and aliphatic aldehydes and ketones may be used, such as benzaldehyde and methylethyl ketone and the like, as well as cyclic ketones, such as cyclohexanone and the like. Aliphatic and cycloaliphatic aldehydes and ketones containing olefinic unsaturation may likewise be employed to form the corresponding unsaturated ester and/or acid. When ketones are oxidized according to the present invention, the product obtained will be the corresponding ester, but in some cases a mixture of the ester and acid will be produced.

In a preferred embodiment, the present invention may be used for the preparation of esters and/or acids of the formula (I) ##STR1## which comprises reacting an aldehyde or ketone of the formula (II) ##STR2## wherein R.sup.1 is alkyl or aryl, R.sup.2 is hydrogen, alkyl or aryl, or R.sup.1 and R.sup.2 are both hydrogen, or R.sup.1 and R.sup.2 together represent alkylene, provided that R.sup.1 and R.sup.2 may not both be methyl. When R.sup.1 and R.sup.2 is alkyl, R.sup.1 and R.sup.2 may be straight or branched chain alkyl, suitably straight or branched chain alkyl of from 1 to about 15 carbon atoms, such as from 1 to about 10 carbon atoms. When R.sup.1 or R.sup.2 is aryl, R.sup.1 and R.sup.2 may be aryl of from 1 to about 4 rings, including fused rings, and may suitably contain from about 6 to about 30 carbon atoms. Suitably, R.sup.1 or R.sup.2 maybe phenyl, naphthyl, biphenyl and the like. When R.sup.1 and R.sup.2 together represent alkylene, the alkylene may suitably be straight or branched chain alkylene of from about 1 to about 15 carbon atoms in the carbon-to-carbon chain, such as from 1 to about 10 carbon atoms in the carbon-to-carbon chain. Usually when R.sup.1 and R.sup.2 together represent alkylene, there will be from about 1 to about 30 carbon atoms in total, preferably from about 3 to about 15 carbon atoms in total.

In the above formulas (I) and (II), alkyl and alkylene may be unsubstituted or substituted by aryl, halogen, nitro or the like, while the aryl may be substituted by alkyl, preferably lower alkyl, i.e. from about 1 to about 6 carbon atoms, halogen, nitro or the like.

Preferably, R.sup.1 may represent alkyl of from about 1 to about 10 carbon atoms, phenyl, or alkylene of from about 3 to about 15 carbon atoms with from about 3 to about 9 carbon atoms in the carbon-to-carbon chain, said alkyl, phenyl or alkylene being unsubstituted or substituted by halogen, cyano or nitro or, in the case of phenyl, lower alkyl. Further, R.sup.2, or both R.sup.1 and R.sup.2 may represent hydrogen.

While sodium perborate tetrahydrate will normally be used, both in terms of economy and convenience, other alkali metal perborates may be employed of the formula (III)

MBO.sub.3.nH.sub.2 O (III)

wherein M is an alkali metal, preferably sodium or potassium, and n is 1 to 4, usually 4. Suitably, the oxidation is carried out with the perborate (III) in the presence of an acid that hydrolyzes in water to form hydronium ions, such as mineral acids, sulfonic acids, organic acids, and the like, but a Lowry-Bronsted acid or Lewis acid may also be used, such as BF.sub.3. Glacial acetic acid is safe and economical and hence is presently preferred. Other useful organic acids include trifluoroacetic acid and formic acid.

When an organic acid is employed, it may also serve as a solvent. If a solvent or co-solvent is required, any suitable inert solvent may be employed, such as acetone, halogenated hydrocarbons, such as methylene chloride, chloroform and the like, aliphatic and aromatic esters, benzene and the like. It is noted that acetone, while a ketone, is nevertheless not oxidized by the perborate (III) and hence may be used as a solvent, if desired.

Usually, the oxidation will be initiated at a temperature of from about 30.degree. to about 70.degree. C., usually from about 40 to about 60.degree. C. While lower temperatures can be used, reaction rates will necessarily be slower. Temperatures higher than about 70.degree. C. may be used, if required or desired, depending upon the desired reaction rate. However, the reaction is exothermic and hence external cooling may be needed to control the reaction temperature, even at the lower temperatures employed.

The present invention is illustrated in terms of its preferred embodiments in the following Examples. In this specification and the appended claims, all parts and percentages are by weight, unless otherwise stated.

EXAMPLE 1

Preparation Of Epsilon-Caprolactone

To a 200 ml roundbottom flask was added 4.9 grams (0.05 mole) of cyclohexanone, 50ml of glacial acetic acid, and 11.4 grams (0.075 mole) of sodium perborate tetrahydrate. The mixture was heated to 50.degree. C. using a water bath. The reaction temperature was maintained in the range of 50-55.degree. C., while stirring the mixture with a magnetic stirrer for four hours, after which the reaction mixture was cooled to room temperature, and the solid sodium borate was separated from the mixture using section filtration. The acetic acid was stripped from the remaining liquid residue using a rotary evaporator, and the remaining epsilon-caprolactone was purified by vacuum distillation. Yield: 91% theoretical.

EXAMPLE 2

Preparation of Benzoic Acid

The procedure of Example 1 was followed using 5.3 grams (0.05 mole) of benzaldehyde as the starting material. Crude benzoic acid formed was purified by recrystallization. Yield: about 50% theoretical.

EXAMPLES 3-6

Following the procedure of Example 1, the ketones set forth below were oxidized with sodium perborate at a temperature of about 55.degree. C. to provide the esters and acid set forth in Table 1 below.

                  TABLE 1
    ______________________________________
    Example
           Starting Material
                        End Product      Yield
    ______________________________________
            ##STR3##
                         ##STR4##        75%
    4
            ##STR5##
                         ##STR6##        74%
    5
            ##STR7##
                         ##STR8##        68%
    6
            ##STR9##
                         ##STR10##       24%
                        HOOC(CH.sub.2).sub.5COOH
                                         38%
The most current patent detailing this reaction process, which has links to the relevant patent history of the prior art, is as follows:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=2&f=G&l=50&co1=AND&d=ptxt&s1=%27sodium+perborate%27&s2=Baeyer-Villiger&OS=%22sodium+perborate%22+AND+Baeyer-Villiger&RS=%22sodium+perborate%22+AND+Baeyer-Villiger



psychokitty

  • Guest
Methyl-(a-alkyl-)-styryl ketones
« Reply #38 on: October 13, 2004, 09:35:00 AM »
Information in this post relevant to this thread taken from the PDF documents found in

Post 531053

(psychokitty: "Propenylbenzenes anyone?", Chemistry Discourse)
:

SOME ALPHA-ALKYLCINNAMIC ACIDS AND THEIR DERIVATIVES
BY MARSTON TAYLOR BOGERT AND DAVID DAVIDSON
J.A.C.S. v. 54 pp.334-338 (1939)


The phenomenal success of a-amylcinnamic aldehyde and other a-alkylcinnamic aldehydes as perfume bases, led us to prepare several of the corresponding methyl ketones (methyl- (a-alkyl-)-styryl ketones) (111). These were synthesized by condensing benzaldehyde with alkyl acetones (11) by means of hydrogen chloride. . . .

. . . Ethyl, n-propyl, n-butyl and n-amyl derivatives are reported in this paper. The attempt to prepare the isopropyl derivatives by starting with isopropyl acetone, (CH3)2CHCH2COCH3, gave an anomalous result, since it was not found possible to prepare a solid oxime from the supposed methyl (a-isopropyl-)-styryl ketone, nor to oxidize it to a-isopropylcinnamic acid. . . .

Experimental:

One-half mole of benzaldehyde was mixed with one mole of the alkyl acetone and one-fourth mole of hydrogen chloride gas passed into the cooled mixture. The mixture, which soon became red, was then shaken for sixteen to twenty hours. At the end of this time the water formed in the reaction had separated as aqueous hydrochloric acid and was removed. Without further treatment, the oil was distilled under diminished pressure (about 20 mm.). Somewhat more than half of the alkyl acetone was recovered and a small residue, probably consisting of dibenzal-alkyl acetone (styryl-( a-alkyl-)- styryl ketone), remained in the flask. The principal fraction, consisting of crude methyl (a-alkyl-)-styryl ketone, was obtained in a yield of about 90% based on the alkyl acetone consumed, or about 75% based on the benzaldehyde employed. The crude alkyl acetone fraction was treated with one-half mole of benzaldehyde and sufficient alkyl acetone to replace that consumed in the first reaction. Hydrogen chloride was then added and the reaction carried out as before. The process was repeated three times but could probably be carried on indefinitely. By using two moles of alkyl acetone to one of benzaldehyde and reworking the recovered alkyl acetone in this way, the amount of dibenzal derivative formed was greatly reduced, with consequent improvement in the yield of the desired product. The crude methyl (a-alkyl-)-styryl ketone may be used directly for the preparation of the a-alkylcinnamic acids. To purify it, the crude product was washed with saturated sodium bisulfite, followed by water and then treated with alcoholic potassium hydroxide, thrown into water, acidified with acetic acid, extracted with benzene, dried over sodium sulfate and distilled. A middle fraction was taken for analysis. The methyl (a-alkyl-)-styryl ketones are liquids having a greenish-yellow tinge, with a floral odor which resembles, but is much weaker than, that of the a-alkylcinnamic aldehydes.


Physiologically Active Phenethylamines. I. Hydroxy- and Methoxy-alpha-methyl-beta-Phenethylamines (beta-Phenylisopropylamines)
E. H. WOODRUFF AND THEODORE W. CONGER
J.A.C.S. Feb 1938 v. 60 pp. 465-467

. . . An excellent preparation for a-alkylcinnamic acids is that recently carried out by Bogert and Davidson" who oxidized with hypohalite methyl (a-alkyl styryl) ketones prepared by condensing benzaldehyde with a methyl alkyl ketone in the presence of dry hydrogen chloride gas. With modification this was found to give excellent yields of the methoxy-a-methylcinnamic acids The other steps in the synthesis follow essentially experimental procedures already appearing in the literature. . . .

. . . When condensing the methoxy aldehydes with methyl ethyl ketone it was necessary to cool the aldehyde-ketone mixture in an ice salt bath during the addition of the hydrogen chloride gas and to allow the reaction to proceed in an electric refrigerator at 0-5 °C or in the freezing chamber at -10 to -5 °C for twenty-four to forty-eight hours, instead of at room temperature. It was found further that a practical grade of methyl ethyl ketone could be used. In this case instead of recovering the unused ketone the reaction mixture was taken up in ether, neutralized with solid sodium carbonate and washed thoroughly with water before drying with anhydrous magnesium sulfate and distilling.

These changes were found to be of particular value in the case of the m-methoxy compound.

psychokitty

  • Guest
Two great articles
« Reply #39 on: October 13, 2004, 10:55:00 AM »
100 Years of Baeyer-Villiger Oxidations
Michael Renz, Bernard Meunier
European Journal of Organic Chemistry Volume 1999, Issue 4 , Pages 737 - 750



Abstract:

In the present review, we report the discovery of the formation of esters and lactones by oxidation of ketones  with a peroxide derivative, namely the Baeyer-Villiger reaction. This reaction was first reported by Adolf von Baeyer and Victor Villiger a century ago in 1899, just one year after the oxidant they used (KHSO5) has been described. Furthermore, Baeyer and Villiger established the composition of this new inorganic peroxide and showed that its instability was the reason of a controversy between several European chemists between 1878 and 1893. For the first 50 years the mechanism of the Baeyer-Villiger reaction was a matter of debate. A side product, 1,2,4,5-tetraoxocyclohexane, was ruled out as an intermediate in the ester formation by Dilthey. Criegee postulated a nucleophilic attack of the oxidant on the carbonyl group. This mechanism was confirmed by von E. Doering by a labeling experiment with [18O]benzophenone. The rearrangement step occurs with retention of the stereochemistry at the migrating center. The competitive migration and the rate-determining step are also discussed in this review.

Chemistry: How green was my ester
GIORGIO STRUKUL
Nature 412, 388 - 389 (26 July 2001); DOI:

doi:10.1038/35086670





Introduction:

Hydrogen peroxide is an ideal oxidant. It cannot yet be used widely, because viable catalysts aren't available for many industrially important processes. But there are encouraging indications of progress.

Chemistry has turned green. The increased awareness of  environmental problems has generated an overly simplistic division, however, especially in the media, between ‘bad’  chemistry — which first pollutes and then (sometimes) cleans up — and ‘good’, green chemistry. Chemists themselves are partly responsible for setting up this misleading contrast. But they are nonetheless among the leaders in trying to find less wasteful or damaging ways to handle the planet’s resources.