Author Topic: OTC way to amphs, F.C w/ Al?  (Read 8182 times)

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Ganesha

  • Guest
Aaah, great post moo! Very clever...
« Reply #20 on: May 19, 2004, 04:01:00 AM »
Aaah, great post moo! Very clever...  ;D  Patents dosen't seem to open for some reason.


armageddon

  • Guest
mono- or dihalogenation
« Reply #21 on: May 19, 2004, 11:34:00 AM »
Hi Bees!

Ganesha: espacenet was offline yesterday I think - now the links work..

But patent 4067886 states the product obtained after hydrolysis is the 1,3-dichloroacetone. I wonder if this double chlorination can be avoided if only 1x molar equivalent of chlorine is used - they suggest using 1-5x molar excess...

EDIT Oops, seems I overread something: "The proportion of chlorine or bromine used will depend on the degree of halogenation desired" - aswers my question quite well  ::) /EDIT

(1,1-dichloro isn't made because of steric hindrances with their intermediate alpha-halogenated ketal, second -Cl attaches to the gamma-carbon - in case of acetone)

And they separate the mono/dichloro by crystallization at -70°C (and call that "easily separable" - well if you have liquid nitrogen, then it's perhaps easy)

As I understand, the rxn is equally good carried out in methanol or DMF at rt (70% yield), giving a mixture of (alpha-)mono- and symetrically dichlorinated ketone with the ratio 3.9:1 (in case of MEK)

But cool thing, indeed!

Greetz A


ning

  • Guest
Hmmm
« Reply #22 on: May 20, 2004, 06:20:00 AM »
Organikum: Nice find. Maybe ZnCl2 will substitute? Shouldn't need a very strong lewis acid. Perhaps even dry HCl.

If conditions are acidic enough, I don't think much 1,1-isomer will be formed. It's not favored. In any case, a brief websearch suggests that 1,1-dichloroacetone melts at around 45 C. So a crystallization and distillation might suffice to separate whatever one produced.

The ketal method is particularly clever, because one could use the formed ketals directly in the friedel-crafts alkylation and hydrolyze them afterwards, perhaps avoiding some nasty side reactions or lachrymatory properties.

I really hope the hive can get some progress on this. A one-step procedure to substituted P2Ps is worth some work.


Ganesha

  • Guest
Aluminium
« Reply #23 on: May 20, 2004, 11:39:00 AM »
Again, somebee should test substituting conventional Lewis acids with aluminium. If Al works as it did for Friedel and Crafts - then we have a 100% OTC route, in every western country.


Nicodem

  • Guest
Zinc
« Reply #24 on: May 21, 2004, 07:46:00 AM »
Well, actually Kinetic already posted a paper where zinc powder is used as a FC catalyst:

Post 408642

(Kinetic: "Zinc promoted Friedel-Crafts acylation", Novel Discourse)
. Don't know about aluminium but if there is no good paper on the subject I ageee it might bee nice to have a volunteer trying it out. Unfortunately I'm out - I don't have any propionyl chloride :P .


Mikael_Bakunin

  • Guest
Friedels-Crafts reactions, possibilities and myths
« Reply #25 on: June 17, 2004, 11:28:00 PM »
Some remarks on FC alkylations:

- I could find nothing on the use of plain Al in these reactions.
- I found that Al/Hg can be used instead of AlCl3

Most important:
- I found in the Kirk-Othmer - under "alkylations" - that the often repeated argument that FC-reactions suffer from polyalkylation because of the activation of the aromatic ring after the first alkylation took place is a myth.

The activation of the ring takes place but is VERY weak. More important is the separation of the formed AlCl3 complexes into a separate phase with the chloroacetone for example and therefor further alkylation gets a problem. VERY strong stirring and/or higher temperatures can overcome the problem. Also the use of FeCl3 so possible might be favorable for this forms no complexes at all and much less catalyst would be needed.

If the use of FeCl3 is not haunted by other problems in a reaction of benzene and chloroacetone is not known to me.

Another fact is the build up of an equilibrium of the resulting compounds in different states of alkylation. Industry for this reason feeds back polyalkylated benzene to shift this equilibrium into the wanted direction. Whoever does this reaction repeatedly can do this too. 

I am aware of the fact that all textbooks tell something else on the polyalkylation, but I trust the Kirk-Othmer. Industry produces cumene in liquid-phase in yields exceeding 98% since a long time. Just as an example.


Last:
- The needed benzene is easily made by boiling toluene or even xylene with a strong FC-catalyst, preferable AlCl3 or better a mixture of AlCl3 and SNCl4. Stannic chloride increases the activity of aluminiumchloride, ferric chloride lowers it.


lugh

  • Guest
Rearrangement to Cumene
« Reply #26 on: June 18, 2004, 01:59:00 AM »

Industry produces cumene in liquid-phase in yields exceeding 98% since a long time.




N-Propylbenzene is the normal Friedel Crafts product from benzene and n-propyl bromide, isopropylbenzene (cumene) is the rearrangement product; thus this isn't a good example for normal yields  :P  Further information on cumene sythesis can be found in the thread starting with

Post 343493 (missing)

(BooWho: "Hydratropic--->p2p Success!", Stimulants)  ;)




Mikael_Bakunin

  • Guest
The industrial cumene production wasnt ...
« Reply #27 on: June 20, 2004, 11:15:00 PM »
The industrial cumene production wasnt intended to be an example for yields to gain with benzene and chloroacetone but as an example for the fact that polyalkylation cant be the major problem. And for this purpose it serves quite well I believe  :) .

The use of FeCl3 might be problematic because of solubility questions - it doesnt dissolve well in benzene as I remember, but as VERY strong stirring is needed anyways this might not be a final drawback.

But the interest on FC-reactions seems to be not very intense anyways at the HIVE, whats a little bit sad I have to say.

MB


Kinetic

  • Guest
F-Cing interesting article
« Reply #28 on: June 21, 2004, 10:32:00 PM »
I agree Mikael, but many fail to see the potential Friedel-Crafts reactions have in clandestine chemistry. I for one am very interested in Friedel-Crafts reactions. But to to the real point of this post:

J. Gen. Chem. USSR, 20, 1950, 450 contains information on Friedel-Crafts reactions using aluminium; the article was translated into English in Chem. Abs. in 1951. This is probably the closest you will get to the use of plain aluminium in Friedel-Crafts alkylations. I hope you enjoy reading it:


The activity of aluminum chloride prepared by the method of Radzivanovskii*
Chemical Abstracts, 45, 1951, 566-567




The F-Cing interesting part

C6H6 (200 g) and 4g Al shavings treated with dry HCl until a brown coating covered the catalyst, then with 100 g EtBr, and let stand 48 hrs. at 10-12°C, followed by refluxing 2 hrs., gave 73% EtPh, b. 132-4°C, d20 0.8703, n20D 1.4950, 16-18% Et2C6H4, mostly the m-isomer with a trace of p-isomer [sepd. according to Voswinkel, Ber. 22, 315(1889)], and 2.5% 1,3,5-Et3C6H3 b. 212-14°C.


* Referenced is an article by Radzivanovskii:

Chemische Berichte, 28, 1135 (1895)

(http://gallica.bnf.fr/Catalogue/noticesInd/FRBNF32711339.htm#listeUC); the article itself can be found by opening the January-May 1895 issue.

lugh

  • Guest
Alkylaction/Acylation
« Reply #29 on: June 25, 2004, 03:25:00 PM »
Kirk-Othmeyer agrees with modern organic chemistry textbooks, as far as the role of carbocations in this reaction:  ;)


Mechanism. The mechanism of alkylation and of other related Friedel­Crafts reactions is best explained by the carbocation concept. The alkylation of benzene with isopropyl chloride may be used as a general example. Lewis acid catalysts, such as A1C13 or BF3, coordinate strongly with non­bonded electron pairs but they interact only weakly with bonded electron pairs. Therefore, n-donor reagents, such as alkyl halides, can react with Lewis acid cat­alysts even under complete exclusion of moisture or any other proton source: However, strong protic acid catalysts are needed when 7r- or Q- donor alkylating agents are used to produce carbocationic or highly polarized donor-acceptor­complexes as the reactive alkylating intermediates: In superacidic media, the carbocationic intermediates, which were long pos­tulated to exist during Friedel-Crafts type reactions (9-11) can be observed, and even isolated as salts. The structures of these carbocations have been studied in high acidity-low nucleophilicity solvent systems using spectroscopic methods such as nmr, ir, Raman, esr, and x-ray crystallography.
Dealkylation, Transalkylation, and Disproportionation. The action of alu­minum chloride also removes alkyl groups from alkylbenzenes (dealkylation, dis­proportionation) (12). Alkylbenzenes, when heated with A1C13, form mixtures of benzene and polyalkylated benzenes: For example, in the industrially important alkylation of benzene with eth­ylene to ethylbenzene, polyethylbenzenes are also produced. The overall forma­tion of polysubstituted products is minimized by recycling the higher ethylation products for the ethylation of fresh benzene (14). By adding the calculated equi­librium amount of polyethylbenzene to the benzene feed, a high conversion of ethylene to monoethylbenzene can be achieved (15).
Polyalkylations. It had been assumed (16) that the tendency toward poly­substitution during Friedel-Crafts alkylation is due to the greater reactivity of the initially produced alkylbenzenes toward further substitution. This kinetic ef­fect, however, has been shown to be limited; the alkyl groups on a benzene nucleus have only a small activating effect on the reaction rate. The actual alkylation occurs in a heterogeneous reaction system, specifically in the acidic catalyst layer, and the reason for polysubstitution is the preferential extraction of the initial alkylates into this catalyst layer allowing ready further alkylation (17). The ten­dency toward polysubstitution may be minimized by the use of a mutual solvent for both the hydrocarbon and catalyst, by high speed stirring, by operating in the vapor phase or at a temperature sufficiently high for the aluminum chloride to be soluble in the hydrocarbon layer.


The entire article from the fourth edition:



;)


lugh

  • Guest
Alkylation/Acylation too
« Reply #30 on: June 25, 2004, 03:27:00 PM »
Catalysts

Friedel-Crafts catalysts are electron acceptors, ie, Lewis acids. The alkylating ability of benzyl chloride was selected to evaluate the relative catalytic activity of a large number of Lewis acid halides.
Acid Halides (Lewis Acids). All metal halide-type Lewis catalysts, gener­ally known as Friedel-Crafts catalysts, have an electron-deficient central metal atom capable of electron acceptance from the basic reagents. The most frequently used are aluminum chloride and bromide, followed by BeC12, CdC12i ZnC12, BF3, BC13, BBr3, GaCl3, GaBr3, TiC14, ZrC14, SnCl4, SnBr4, SbC15, SbCl3, BiCl3, FeC13, and UC14.
In addition, boron, aluminum, and gallium tris(trifluoromethanesulfonates) (triflates), M(OTf)3 and related perfluoroalkanesulfonates were found effective for Friedel-Crafts alkylations under mild conditions (200). These Lewis acids behave as pseudo halides. Boron tris(triflate) shows the highest catalytic activity among these catalysts. A systematic study of these catalysts in the alkylation of aromat­ics such as benzene and toluene has been reported (201).
Easy availability and the low cost of aluminum chloride are partially re­sponsible for its wide use in industry. Although aluminum chloride is frequently thought of as AlCl3, at ordinary temperatures it is, in fact, the dimer Al2Cl6, which prevails up to 440°C; between 440 and 880°C there is an equilibrium mixture of monomer and dimer. At higher temperatures, only the monomer exists, although above 1000°C some ionic dissociation takes place. Under the usual Friedel-Crafts reaction conditions, the catalytically active species is always the monomeric Lewis acid.
Although Friedel and Crafts in their original work described investigations with anhydrous aluminum chloride, it is very difficult to obtain a Lewis acid-type metal halide in an absolutely anhydrous state and exclude moisture or other im­purities during the course of reaction. In view of these facts, it is clear that neither the original inventors, Friedel and Crafts, nor the thousands of subsequent re­searchers who did most successful work with aluminum chloride and related cata­lyst systems, worked under truly anhydrous conditions. Impurities such as water, oxygen, hydrogen halides, organic halides, etc, were present in almost all cases. The presence of traces of moisture has been found to accelerate rather than hinder the reactions. In many cases, the presence of these so-called initiators or cocata­lysts is indeed essential (202). The beneficial action of traces of moisture has been observed especially in reactions involving the olefinic double bond (alkylation with olefins, polymerization, etc).
The inactivity of pure anhydrous Lewis acid halides in Friedel-Crafts poly­merization of olefins was first demonstrated in 1936 (203); it was found that pure, dry aluminum chloride does not react with ethylene. Subsequently it was shown (204) that boron trifluoride alone does not catalyze the polymerization of isobu­tylene when kept absolutely dry in a vacuum system. However, polymers form upon admission of traces of water. The active catalyst is boron trifluoride hydrate, BF3-H20, ie, a conjugate protic acid H+(BF30H)-.
Cocatalysts of two types occur: (1) proton-donor substances, such as hydroxy compounds and proton acids, and (2) cation-forming substances (other than pro­ton), including alkyl and acyl halides which form carbocations and other donor substances leading to oxonium, sulfonium, halonium, etc, complexes.

Metal Alkyls and Alkoxides. Metal alkyls (eg, aluminum boron, zinc alkyls) are fairly active catalysts. Hyperconjugation with the electron-deficient metal atom, however, tends to decrease the electron deficiency. The effect is even stronger in alkoxides which are, therefore, fairly weak Lewis acids. The present discussion does not encompass catalyst systems of the Ziegler-Natta type (such as AlR3 + TiCl4), although certain similarities with Friedel-Crafts systems are apparent.
The most important application of metal alkoxides in reactions of the Frie­del-Crafts type is that of aluminum phenoxide as a catalyst in phenol alkylation (205). Phenol is sufficiently acidic to react with aluminum with the formation of (C6H5O)3A1. Aluminum phenoxide, when dissolved in phenol, greatly increases the acidic strength. It is believed that, similar to alkoxoacids (206) an aluminum phenoxoacid is formed, which is a strong conjugate acid of the type HAl(OC6H5)4. This acid is then the catalytically active species Protic Acids (Brdnsted Acids). Sulfuric acid is among the most used Bronsted acids for the Friedel-Crafts reactions, especially in hydrocarbon conver­sions, and in alkylation for the preparation of high octane gasoline. Anhydrous HIP has replaced in part sulfuric acid, because of its convenience, although the toxic hazardous nature of HIP is causing environmental concerns in its industrial use. Trifluoromethanesulfonic acid [1493-13-6] (and related superacids) are also gaining significance. Triflic acid does not react with aromatics (whereas sulfuric acid causes sulfonation) and thus offers substantial advantages with aromatic systems.
Acidic Oxides and Sulfides (Acidic Chalcogenides). Chalcogenide cata­lysts include a great variety of solid oxides and sulfides; the most widely used are alumina or silica (either natural or synthetic), in which other oxides such as chromia, magnesia, molybdena, thoria, tungsten oxide, and zirconia may also be present, as well as certain sulfides such as sulfides of molybdenum. The compo­sition and structure of different types of bauxites, floridin, Georgia clay, and other natural aluminosilicates are still not well known. Some synthetic catalysts, other than silica-alumina compositions, representative of the acidic chalcogenides are
BeO, Cr203, P205, Ti02, and A12(SO4)3 which may be regarded as A1203, 3SO3, A1203.xCr2O3, A1203.Fe203, Al2O3-MnO, Al2O3.CoO, Al203.Mo203, Al203.V203, Cr2O3•Fe2O3, MoS2, and MoS3. In contrast to sulfuric acid which may be regarded
as a fully hydrated chalcogenide, the members of this group are seldom very highly hydrated under conditions of use.
Silica-alumina has been studied most extensively. Dehydrated silica­alumina is inactive as isomerization catalyst but addition of water increases ac­tivity until a maximum is reached; additional water then decreases activity. The effect of water suggests that Bry nsted acidity is responsible for catalyst activity (207). Silica-alumina is quantitatively at least as acidic as 90% sulfuric acid (208).
Acidic Cation-Exchange Resins. Bronsted acid catalytic activity is respon­sible for the successful use of acidic cation-exchange resins, which are also solid acids. Cation-exchange catalysts are used in esterification, acetal synthesis, ester alcoholysis, acetal alcoholysis, alcohol dehydration, ester hydrolysis, and sucrose inversion. The solid acid type permits simplified procedures when high boiling and viscous compounds are involved because the catalyst can be separated from the products by simple filtration. Unsaturated acids and alcohols that can poly­merize in the presence of proton acids can thus be esterified directly and without polymerization.
Sulfonated styrene-divinylbenzene cross-linked polymers have been applied in many of the previously mentioned reactions and also in the acylation of thiophene with acetic anhydride and acetyl chloride (209). Resins of this type (Dowex 50, Amberlite IR- 112, and Permutit Q) are particularly effective catalysts in the alkylation of phenols with olefins (such as propylene, isobutylene, diisobutylene), alkyl halides, and alcohols (210)
Superacids. Bronsted Superacids. In the 1960s a class of acids hundreds of millions times stronger than mineral acids was discovered; acids stronger than 100% sulfuric acid are called superacids (211). The determination of acidity by pH measurement does not hold for very concentrated acid solution. Hammett's logarithmic acidity function is generally used (212). where pKBH+ is the dissociation constant of the conjugate acid and BB is the ionization ratio. Typical Ho values are - 12.6 for 100% H2SO4, and - 11.0 for anhydrous HF. Although more recent Ho measurements on completely anhydrous HF have shown acidities comparable to that of FSO3H (- 15.1) (213).Fluorosulfuric acid [7789-21-1] (HSO3F) is one of the strongest BrOnsted acids known with H,, = -15.1. This acidity is somewhat lower than that of H2SO4 - SO3, ie, H2S207. However, because of its stability, ease of purification, its wide liquid range (mp = - 89°C, by = 162°C) and relatively low viscosity (1.56 mPa•s( = cP) at 28°C), it is more convenient to use. Perfluoroalkanesulfonic acids also show high acidity. The parent trifluoro­methanesulfonic acid (triflic acid), CF3SO3H, is commercially prepared by elec­trochemical fluorination of methanesulfonic acid (214). It has an Ho value of - 14.1 (215,216). The higher homologues show slightly decreasing acidities. Super Lewis Acids. Acid systems stronger than anhydrous AiC13 are classi­fied as super Lewis acids (211). By this definition, Lewis acids such as SbF5, NbF5, AsF5, and TaF5 are so categorized.Bronsted-Lewis Superacids. Conjugate Friedel-Crafts acids prepared from protic and Lewis acids, such as HCl-AIC13 and HCl-GaC13 are, indeed, superacids with an estimated Ho value of - 15 to - 16 and are effective catalysts in hydro­carbon transformation (217).In the early 1960s acid systems were prepared comprising a pentafluoride of group V elements, particularly SbF5 and a strong Bronsted acid such as HF, FSO3H, CF3SO3H, etc (218). Magic Acid [33843-68-4] (HSO3F-SbF5) is one of the strongest members of the system; fluoroantimonic acid [16950-06-4], HF-SbF5, even surpasses Magic Acid in its acidity. The acidity of HF or HSO3F is increased sharply by adding SbF5 (219,220). These very highly acidic systems are being utilized in transformations such as isomerization of straight-chain alkanes (221), alkane-alkene alkylations (222), and the like (223). CF3SO3H-SbF5 and CF3SO3H-B(OTf)3 have been shown to be highly effective catalysts for Friedel­Crafts alkylation and isomerization reactions (224).
Solid Superacids. Most large-scale petrochemical and chemical industrial processes are preferably done, whenever possible, over solid catalysts. Solid acid systems have been developed with considerably higher acidity than those of acidic oxides. Graphite-intercalated AIC13 is an effective solid Friedel-Crafts catalyst but loses catalytic activity because of partial hydrolysis and leaching of the Lewis acid halide from the graphite. Aluminum chloride can also be complexed to sulfonate polystyrene resins but again the stability of the catalyst is limited. More stable catalysts are obtained by using fluorinated graphite or fluori­nated alumina as backbones, and Lewis acid halides, such as SbF5, TaF5, and NbF5, which have a relatively low vapor pressure. These Lewis acids are attached to the fluorinated solid supports through fluorine bridging. They show high reac­tivity in Friedel-Crafts type reactions including the isomerization of straight­chain alkanes such as n-hexane. Another type of solid superacid is based on perfluorinated resin sulfonic acid such as the acid form of Du Pont's Nafion resin, a copolymer of a perfluorinated epoxide and vinylsulfonic acid or solid, high molecular weight perfluoroalkane­sulfonic acids such as perfluorodecanesulfonic acid, CF3(CF2)9S03H. Such solid catalysts have been found efficient in many alkylations of aromatic hydrocarbons (225) and other Friedel-Crafts reactions (226).
Superacidic Zeolites. The well-defined crystal structures of both natural and synthetic zeolites permit selective hydrocarbon transformations. The selectivity of the zeolites can be improved by deactivations of external acid sites with amines, replacement of the cationic sites by transition metal ions by ion-exchange, or by modification of the silica-alumina ratio. Some zeolites such as H-ZSM-5 and the like display superacidic character at high temperatures. The have found wide utility in electrophilic aromatic alkylations, transalkyla­tions, disproportionation, hydrocarbon synthesis, and more importantly, metha­nol conversion to hydrocarbons, including fuel gas and gasoline (227). H-ZSM-5 was also used as an efficient catalyst for the thermal degradation of polypropylene into gasoline range hydrocarbons (228). Various pillared clays obtained by reac­tion of metal trihalides with the hydroxyl groups on clays act as selective cata­lysts, especially in transalkylations (229).


8)


Organikum

  • Guest
Wow ! Radzivanovskii !
« Reply #31 on: June 25, 2004, 07:43:00 PM »
Thats the hit, thanks Kinetic!

It is quite similar to the patent posted before where AlCl3 is made by HCl/Al in benzene with some AlCl3 as activating compound. But this gets much better. No activator needed and catalyst formation in situ....

"Radzivanovskii". This explains why the method got not more popular in the western world  ;D

Provided there are not some practical drawbacks this says "BMX + Al + monochloroacetone = P2P".


impressed
ORG


Polverone

  • Guest
Dolgov's articles on F-C with Al shavings and HCl
« Reply #32 on: July 06, 2004, 05:24:00 AM »
I was able to find 3 articles by Dolgov and collaborators on F-C reactions using a catalyst comprised of Al shavings treated with dry HCl gas in benzene. This catalyst appears attractive because of its easy preparation and good activity (notice how little catalyst is used compared to ordinary AlCl3 in standard preparations).

Here are major portions of Dolgov's 3 articles on this catalyst that I was able to find in J. Chem. Soc. USSR (English translation).

THE ACTIVITY OF ALUMINUM CHLORIDE PREPARED BY THE RADSIWANOWSKI* METHOD

1. THE EFFECT OF AlCl3 PREPARED BY THE RADSIWANOWSKI METHOD UPON THE C6H6 + C2H5Br REACTION

B.N. Dolgov and N.A. Kuchumova J Gen. Chem USSR 1950, pg 469-473 (English translation)

*This is how the English translator spelled it.

Highlights from article:

Investigation of the rate at which "AlCl3-R" (AlCl3-Radsiwanowski) is formed from Al shavings and HCl gas showed that 4 to 5 hours suffice for treating the mixture of benzene and Al shavings, all other quantities remaining the same (adding 2% of Al shavings and a temperature of 10-12 degrees). Any further treatment of the mixture with HCl gas increases the quantity of desalkylation products.

It is stated in the literature that activated aluminum must be used in the preparation of AlCl3 whenever Radsiwanowski AlCl3 is used in a Friedel-Crafts reaction. The best method of activation is calcining the Al shavings at 300 degrees for 30 minutes. We ran a series of tests with Al shavings activated as indicated above. Our results showed that the
preliminary activation has no effect on the preparation of AlCl3 from shavings; in our subsequent research we therefore employed ordinary unactivated shavings.

A series of tests made with varying quantities of Al shavings, from 1% to 10% by weight relative to benzene, showed the optimum quantity to be 2%. Some results from these tests:

Al shavings, g: 1 Ethylbenzene yield: 68% Diethylbenzene yield: 17% Trietheylbenzene yield: 1% Tetraethylbenzene yield: -
Al shavings, g: 2 Ethylbenzene yield: 73% Diethylbenzene yield: 18% Trietheylbenzene yield: 3% Tetraethylbenzene yield: a few drops
Al shavings, g: 4 Ethylbenzene yield: 63% Diethylbenzene yield: 11% Trietheylbenzene yield: 7% Tetraethylbenzene yield: a few drops
Al shavings, g: 5 Ethylbenzene yield: 54% Diethylbenzene yield: 11% Trietheylbenzene yield: 7% Tetraethylbenzene yield: 2%
Al shavings, g: 5 Ethylbenzene yield: 45% Diethylbenzene yield: 12% Trietheylbenzene yield: 8% Tetraethylbenzene yield: 3%
Al shavings, g: 10 Ethylbenzene yield: 40% Diethylbenzene yield: 10% Trietheylbenzene yield: 10% Tetraethylbenzene yield: 3%

Remarks: in all of the tests, 40% of benzene was driven off, based on the amount of benzene placed in reaction.


EXPERIMENTAL

All tests were made in a standard apparatus, consisting of a 500 ml RBF fitted with a ground-in reflux condenser and a tube (likewise ground-in) reaching to the bottom of the flask for passing the HCl gas through. The flask was filled with 200 g of pure anhydrous benzene, and 4 g of Al shavings (2%), and a current of anhydrous HCl gas was passed through until the Al shavings were coated with a brown film. Then 100 g of freshly distilled ethyl bromide was added drop by drop, the flask being chilled by ice. After the violent evolution of HBr gas had ended, the mixture was set aside to stand at room temperature for 48 hours and then heated with a reflux condenser to the boiling point of benzene over a water bath for 2 hours. Upon cooling, the reaction products were decomposed with water, saponified, dessicated over CaCl2, and then distilled twice into a herringbone dephlegmator.

Under these conditions, a yield of 72% ethylbenzene was recovered (percentage yield based on ethyl bromide).

2. CONDENSATION OF BENZENE WITH SOME UNSATURATED ALIPHATIC HALOGEN DERIVATIVES AND POLYHALOGEN DERIVATIVES

B.N. Dolgov and N.A. Larin J Gen. Chem USSR 1950, pg 475-483 (English translation)

(All reported fractions are after benzene has been driven off)

1) Condensation of 1,2-dichloroethane with benzene. Optimum amount of Al shavings: 2% by weight. Diphenylethane yield rises as the percentage of benzene is increased, tar decreasing correspondingly. For example: 1:1 ratio of benzene to dichloroethane gives 6.4% diphenylethane, 24.1% tar, but 8:1 ratio gives 30.6% diphenylethane, 2.9% tar. Within the 16-80 degree temperature range, increasing temperature increases tar but does not markedly affect diphenylethane yield. Time makes a large difference. Reaction time of 2 hours gives 4% diphenylethane, 1.2% tar. 24 hours gives 25.2% diphenylethane, 7.6% tar. 48 hours gives 26.2% diphenylethane, 14% tar. Some asymmetrical 1,1 diphenylethane was recovered by further fractionation of the fraction of product boiling in the range 260-290. Dibromoethane gave very similar results when used instead of dichloroethane.

2) Condensation of isobutylene bromide with benzene. This condensation was performed under the following conditions: bromide:benzene ratio of 1:4, 2% Al (based on benzene), and reaction at room temperature for 25 hours. After decomposition with water and dessication of the oily layer with CaCl2, the benzene was driven off, and the residue separated into the following fractions:

I (BP 90-160): 4 g
II (BP 167-179): 6.5 g
III (BP 260-293): 28.82

A solid cake of residue remained in the flask. Fraction I is the initial dibromide with traces of the decomposition products and benzene. II proved to be a mixture of isobutyl- and tert-butylbenzenes. Bromination of the product in direct sunlight by the Schramm method enabled us to show that the mixture contained 89% of the tertiary isomer, produced by the isomerization of the isobutylbenzene.

Repeated fractionation of Fraction III yielded an oil with BP 284-288, which proved to be the principal reaction product, 1,1-dimethyl-1,2-diphenylethane, described by Bodroux. The yield of this substance is as much as 45% of the theoretical. It was found that Fraction III also contained minute amounts of 1,2-dimethyl-1,2-diphenylethane.

3) Condensation of 2-methyl-3-chloropropene with benzene (omitted - products similar to those above)

4) Condensation of allyl bromide with benzene. Conditions were similar to those above (1:4 bromide:benzene, 2% Al, 24 hours at room temperature). Fraction I BP 148-152, 1.9 g colorless liquid. Fraction II BP 266-290, 14.8 g of liquid with a lilac fluorescence. Fraction III, BP above 300: 10.6 g thick, dark-brown tar. Repeated fractionation of Fraction I yielded an oil that boiled at 148-150 and proved to be propylbenzene. Repeated fractionation of Fraction II yielded a liquid that boiled at 279-281 and exhibited the beautiful lilac fluorescence of diphenylpropane. We did not examine the product in greater detail.

5) Condensation of 1,2,3-tribromopropane with benzene. The conditions: tribromide:benzene 1:6, 2% Al, room temperature, 20 hours. Some 10% of diphenylpropane was recovered; none of the expected triphenylpropane was found.

6) Condensation of 2-methyl-1,2,3-tribromopropane with benzene. 100 g of benzene and 63 g of bromide (1:6 bromide:benzene) were used, 2% Al, room temperature for 20 hours. The condensate was distilled in a 5 mm vacuum after decomposition with water, drying, and driving off benzene.

Fraction I BP 82-85 5.3 g
Fraction II BP 110-112 15.0 g

11.4 g of thick, dark tar remained in the flask.
Fraction I proved to be unreacted tribromide. Fraction II, after standing overnight, yielded 10 g of crystals, which exhibited a m.p. of 125 degrees after recrystallization from alcohol and caused no depression when mixed with 1,2-dimethyl-1,2-diphenylethane.

7) Condensation of of 2-methyl-1,2-dibromo-3-chloropropane with benzene. The conditions were similar to those in the above reaction. Likewise, a 108-111 degree (at 5 mm) fraction was obtained, which yielded 8 g of crystals after standing for 24 hours; these crystals proved to be 1,2-dimethyl-1,2-diphenylethane.

8) Condensation of 1,1,2,2-tetrachloroethane with benzene. 1:6 ratio of chloride to benzene was used, at 20 degrees for 20 hours with 2% Al. After the benzene and unreacted chloride were driven off, 0.5 g of anthracene were eventually recovered. When the reaction was carried out at 70-75 degrees with 6% Al, the condensation proceeds differently, yielding 2.8 g of 1,2-diphenylethane.

9) Condensation of tetrachloroethylene with benzene. The reactants were used in a 1:6 chloride:benzene ratio, at temperatures from 19 to 70 degrees and with up to 10% of Al. No condensation was observed in any experiment.

Summary:

1. AlCl3-R acts like ordinary AlCl3 in promoting cleavage and isomerization in condensation reactions.

2. An increase in the number of halogen atoms in the halogen derivative reduces the latter's ability to enter into condensations.

3. A halogen atom attached to the double bond is practically unreactive in the presence of AlCl3.

3. CONDENSATIONS OF BENZENE WITH ALIPHATIC MONOHALOGEN DERIVATIVES

B.N. Dolgov, N.I. Sorokina and A.S. Cherkasov J. Gen. Chem. USSR 1951 563-576 (English translation)

...A Friedel-Crafts reaction of benzene with methyl iodide in the presence of 33% AlCl3 does not take place in the cold or with the application of heat. Only at a pressure of 1.5 atm and a temperature of 80-90 degrees did the authors observe the evolution of HI and the formation of products that had boiling points from 78-135 degrees. We have not found any other references in the literature to this reaction. The reaction takes place with great ease under Radsiwanowski conditions, which testifies to the very high activity of the catalyst compared to ordinary aluminum chloride. The reaction rate is not high at room temperature, but it is vigorous and thoroughgoing at 40 degrees, yielding a mixture of all the methylated benzenes from toluene to hexamethylbenzene inclusive. Increasing the Al percentatge in the reaction mixture promotes greater methylation.

...

The results obtained under various conditions with chloro and bromo alkyls enabled us to set up interesting patterns of behavior. The yields of the monoalkyl benzenes, which are the primary reaction products, drop off as the molecular weight of the radicals increases, products of deeper condensation being formed.

... We see that the use of bromo alkyls always lowered the yields of the alkyl benzenes somewhat...

EXPERIMENTAL
Preparation of Radsiwanowski AlCl3. 144% of aluminum shavings (based on wt of benzene) was added to a flask containing anhydrous benzene, and anhydrous HCl gas was pass through for 3-4 hours at ordinary temperature. The formation of AlCl3 was accompanied by the evolution of bubbles of gas, the benzene grew dark, and the shavings were covered with a deposit of AlCl3. After standing overnight, the mixture was ready for the addition of other reaction components.

1) Condensation of benzene with methyl iodide (omitted)

2) Condensation of benzene with isopropyl chloride and bromide. As in all the other instances, the benzene was prepared by distilling commercial benzene, the first 10% of the distillate, which contained water, being discarded. The isopropyl chloride was dried above CaCl2 and then distilled. The fraction with BP 36-36.5 degrees was selected. Tests were run for 20 hours at 10-12 degrees with a 1:4 ratio of chloride and benzene. Maximum of isopropylbenzene yield was with 2% Al, being 45% of theoretical. Increasing Al increases polyalkylation, increasing isopropyl chloride increases condensation products/tar. The maximum yield with isopropyl bromide did not exceed 31%. Di- and tri-isopropylebenzenes were also isolated and characterized (omitted).

3) Condensation of benzene with isobutyl chloride and isobutyl bromide. The reaction was effected by boiling the benzene/halide mixture in presence of catalyst. Reaction was difficult to start, yield was poor in all cases, maximum (18%) achieved with isobutyl chloride in 1:4 ratio with 2% Al. Carrying out the reaction at room temperature for 18 hours yielded up to 41% of theoretical butylbenzene yield.

4) Condensation of benzene with isoamyl chloride and bromide. Principle product was tert-amylbenzene, maximum yield 18% (all reactions here were done at boiling temperature for relatively short periods of time).

5) Condensation of benzene with chloroform. More diphenylmethane was formed as more Al was used; more diphenylmethane is also formed with the addition of CuCl. Yield of diphenylmethane could be slightly above 40%. No more than 3-4% triphenylmethane could be recovered under any conditions, and this required tedious extraction from tar.


Osmium

  • Guest
> notice how little catalyst is used ...
« Reply #33 on: July 06, 2004, 12:26:00 PM »
> notice how little catalyst is used compared to ordinary
> AlCl3 in standard preparations

It might have been mentioned already (too lazy to read the whole thread again) that there are two types of FC reactions: alkylations and acylations.

The alkylations (using R-X + )are reversible and require only a small amount of catalyst since that catalyst is reformed once a reaction took place.

In the case of acylations (which use acid halogenides, R-COX) the catalyst will form a complex with the reaction product and will be lost, that's why equimolar amounts have to be used!


synthon

  • Guest
Double WOW
« Reply #34 on: July 06, 2004, 03:57:00 PM »
Excellent find, Kinetic!

Those interested in methamphetamine manufacture should really read this thread. Provided that you can get sodiumborohydride (or HgCl2) and benzene the path to meth is OTC, and dirt-cheap too. For amphetamine - even better only ammoniumformate and benzene.

EDIT: Probably an impossibility but, it would be interesting to see if sodiumdithionite can reduce the R=N-CH3 to R-NH-CH3... What do you think?

Organikum

  • Guest
AlCl3, TiCl4 and SnCl4 form complexes with...
« Reply #35 on: July 06, 2004, 04:33:00 PM »
AlCl3, TiCl4 and SnCl4 form complexes with very many compounds so the catalytic amount of theoretically needed often not suffices in FC-alkylations. The classical chloroacetone/benzene synthesis calls for about 2,1 molar equivalents of AlCl3 - also it is an alkylation it seems there is a double complex formed on the phenylacetone, once on the keto and once on the methylgroup. This correspondends with the article which was provided by LEGO times ago where the keto-group was protected and such only one equivalent of SnCl4 was needed.
One idea behind the invention of solid acid catalysts like K10 is that they dont complex and - in theory. There is some evidence - far from proven, but there is - that the Radzivanovskii catalyst might resemble a kind of solid supported catalyst, non-complexing or less complexing.
FeCl3 was told to form no complexes.
TiCl4 was told not to polyalkylate.

The question remains if not complexes formed on the keto-group are essential as they might serve as a kind of protecting group themselves.

synthon, might you elaborate how you come to talk about NaBH4 and HgCl2 as essential? I just cant follow you here...

ORG


synthon

  • Guest
synthon, might you elaborate how you come to...
« Reply #36 on: July 06, 2004, 04:55:00 PM »
synthon, might you elaborate how you come to talk about NaBH4 and HgCl2 as essential? I just cant follow you here...

Well, I was talking about the reduction of the Schiff base. If you react P2P with methylamine, you get an imine that you need to reduce somehow, as suggestions I presented sodiumborohydride and HgCl2 (used to make up an Al/Hg amalgam). Did I say that they are essential? There are numerous of other reducing agents. I'm sure you know this allready, I might have been unclear in my previous post.

Organikum

  • Guest
acetol - a possibility?
« Reply #37 on: July 10, 2004, 09:58:00 PM »
Lately it came to my mind that the to chloroacetone similar alcohol - acetol - might be usable in a FC-reaction with benzene to form P2P (or maybe due rearrangement to propiophenone what needs re-rearrangement then, so possible).
edit: corrected my mistake writing P1P instead propiophenone after lugh´s hint
This would avoid the nasty chloroacetone and perhaps even H2SO4 would suffice as FC-catalyst (see: benzene + IPA = isopropylbenzene)

But I found almost no information on acetol, its production and its uses.

Some stuff from the Merck:
Acetol, CAS 116-09-6, CAS name: 1-hydroxy-2-propanone
add. names: hydroxyacetone, acetone alcohol, acetylcarbinol, acetylmethanol, 2-oxopropanol
Formula: C3H6O2, H3CCOCH2OH,
Properties: d=1,0872, bp=147 (decomposes), can be distilled under reduced pressure though. Miscible with water.

Maybee I used the wrong terms for searching, but I got nothing helpful back, neither here nor from Google and my books didnt help me much further too.

Any information on production, properties and uses is highly welcome, even if it should turn out that it is not usable in a FC-reaction with benzene.

regards
ORG  :)


lugh

  • Guest
Pyruvic Alcohol
« Reply #38 on: July 10, 2004, 10:37:00 PM »
Acetol is more commonly known as pyruvic alcohol, generally made in the laboratory means of hydrolysis of the ester formed from potassium acetate or formate and chloro or bromoacetone in dry methanol: Perkin, JCS 59 786 (1891), Nef Ann 335 247 (1904) and Levene & Walki Or Syn 10 1 (1930); pyrochemical decomposition of glycerol: (Nef) and by heating alpha bromopropanaldehyde for 10 to 15 hours in a methanolic solution of an alkali formate: (Nef)  :)  It's main use is as a solvent for nitrocellulose. Generally speaking, alcohols are used in Friedel-Crafts alkylations, not acylations; it's hard to say what will result with the carbonyl group involved as well as the hydroxyl  ;)


Kinetic

  • Guest
Original Friedel-Crafts papers
« Reply #39 on: July 31, 2004, 09:16:00 PM »
In their original paper on the subject, Friedel and Crafts do indeed report the use of aluminium metal for alkylations, added as filings or thin sheets. The reaction reportedly starts slowly, and builds up as the evolved HCl gas reacts with the aluminium to form AlCl3 in-situ. The first article below deals with alkylations and the second focuses on acylations:


Sur une nouvelle méthode générale de synthèse d'hydrocarbures, d'acétones, etc.
C. Friedel, J. M. Crafts
Compt. Rend.
, 84, 1392-1395 (1877)




Sur une nouvelle méthode générale de synthèse d'hydrocarbures, d'acétones, etc.
C. Friedel, J. M. Crafts
Compt. Rend.
, 84, 1450-1454 (1877)