Author Topic: A great piperonal patent  (Read 6650 times)

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Antoncho

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A great piperonal patent
« on: October 08, 2003, 04:50:00 AM »

Patent US4335263

contains a lot of jucy info, which all relates to making specifically piperonal (and other aldehydes as well) from para- or meta- cresol. The info is  chemically miscellanious and each piece could bee applied to some other synthetic pathway as well. So i decided to post it as a separate whole.

Here's what the novel 'jucy' moments of the patent are:

1. Making the acetophenone: introduction of the acetyl moiety into the nucleus via esterification of the phenol followed by Fries rearrangement with AlCl3.

2. Dakin oxidation (with NaOH/H2O2) of the hydroxy-acetophenone to catechol: never seen this rxn work on acetophenones bee4, only on aldehydes.

3. Then, the methylenation step is pretty novel and very high-yielding (for that solvent-to-reactant ratio, at least): the aqueous phenolate is added dropwise into DMSO/DCM mixture. I bet this way is superior to what we previously knew (adding aq. base into a DMSO/DCM/catechol mixtr).

4. Finally, the interesting variation of turning a benzyl halide into benzaldehyde - using nothing but DMSO and Na2CO3! (Example 1)


Shall i remind that there are some other ways of turning a toluene into a benzaldehyde: the most ecological one is undoubtedly refluxing it with an xcesss of activated MnO2 in heptane or some high-boiling naphtha (3-4 hrs, intensive stirring). That's Assholium's favorite method :) ,

Post 429514 (missing)

(Assholium: "åñòü êàêèå-òî ìûñëè?", Russian HyperLab)


There also exists an easyish procedure employing a peroxodisulfate and some Fe/Cu salt, as in (.... shit, i can't find that patent - both on Espacenet and here, on the Hive - it's been posted at least two times! HELP!)

Here is the experimental:



EXAMPLE 1

1.0 mol of an m- and p-cresol mixture (m-/p-=6/4) (I-1), 4.0 mols of acetic anhydride, and 0.005 mol of sulfuric acid were reacted for 1 hour under reflux condition. After completion of the reaction, unreacted acetic anhydride and acetic acid formed as a by-product were distilled off to quantitatively obtain cresol acetate (IV-1).

Then, to 1.0 mol of the thus-obtained compound (IV-1) was added 1.3 mols of aluminum chloride at 90 DEG to 110 DEG C. over 2 hours, followed by elevating the temperature and continuing stirring for 2 hours at 160 DEG to 170 DEG C. After completion of the reaction, the reaction mixture was cooled to 100 DEG C., and decomposed with a 10% hydrochloric acid aqueous solution. After extracting with toluene, the toluene was distilled off from the resulting organic layer to obtain 2-hydroxy-4- and -5-methylacetophenone (III-1) in 90% yield.

0.8 mol of the thus-obtained compound (III-1) and 0.9 mol of 30% hydrogen peroxide were dissolved in a mixture solvent composed of a 4-fold amount by weight of dioxane and a 4-fold amount by weight of water, based on (III-1). 0.9 mol of 30% sodium hydroxide was added dropwise thereto at 0 DEG to 10 DEG C. over 2 hours while blowing nitrogen thereinto. Stirring was further continued for 3 hours at the same temperature. After completion of the reaction, dilute hydrochloric acid was added to the reaction mixture to make it weakly acidic, followed by extraction with diethyl ether. Upon distilling off the solvent from the resulting organic layer, there was obtained 4-methylcatechol (V) in 94% yield.

Then, 0.7 mol of the thus-obtained compound (V) and 1.6 mols of sodium hydroxide were dissolved in a 1.5-fold amount by weight, based on the weight of (V), of water, and the solution was added dropwise to a solution composed of a 5-fold amount by weight of dimethyl sulfoxide and a 1.2-fold amount by weight of dichloromethane, the respective amounts being based on the weight of (V), at 90 DEG to 100 DEG C. under reflux condition. The dropwise addition took 3 hours. Water azeotropically discharged during the dropwise addition was separated off. The reaction was continued for 2 hours at the same temperature. After completion of the reaction, a 2.5-fold amount by weight, based on (V), of water was added to the reaction mixture, and 3,4-methylenedioxytoluene (VI-1) was distilled out as an azeotropic mixture. Yield was 92%.

Alternatively, a solution composed of 0.7 mol of the compound (V) obtained by the above process, 1.75 mols of sodium hydroxide, and a 2.8-fold amount by weight, based on (V), of water was added dropwise to a solution composed of a 1.6-fold amount by weight, based on (V), of water, 2.0 mols of dibromomethane, and 0.007 mol of tetra-n-butylammonium bromide over 5 hours under reflux condition. After completion of the dropwise addition, the mixture was maintained at the same temperature for 2 hours while stirring. After completion of the reaction, the reaction mixture was extracted with toluene and, after liquid separation, the toluene was distilled off from the resulting organic layer. Distillation of the residue gave 3,4-methylenedioxytoluene (VI-1) in 89% yield.

Then, 0.6 mol of the thus-obtained compound (VI-1) and 0.006 mol of benzoyl peroxide were dissolved in a 3.5-fold amount by weight, based on (VI-1), of carbon tetrachloride, and 0.66 mol of bromine gas was blown thereinto under reflux condition. The blowing time was 10 hours. After completion of the reaction, the solvent was distilled off to obtain 3,4-methylenedioxybenzyl bromide (VII-1) in 90% yield.

0.5 mol of the thus-obtained compound (VII-1) was added dropwise to 0.75 mol of sodium bicarbonate and a 3-fold amount by weight, based on (VII-1), of dimethyl sulfoxide at 20 DEG to 30 DEG C., followed by stirring at the same temperature for 4 hours. Then, the reactants were reacted for 5 hours at 70 DEG to 80 DEG C. After completion of the reaction, the reaction mixture was poured into water and, after extraction with diethyl ether and liquid separation, the diethyl ether was distilled off from the resulting organic layer. Distillation of the concentrated residue gave heliotropin (b.p. 131 DEG to 135 DEG C./10 mmHg) in 79% yield.

EXAMPLE 2

1.0 mol of the same m- and p-cresol mixture as used in Example 1 (I-1), 1.0 mol of acetyl chloride, and 2.2 mols of titanium tetrachloride were reacted in nitrobenzene at 70 DEG C. for 6 hours. After completion of the reaction, steam distillation of the reaction mixture gave the end product of 2-hydroxy-4- and -5-methylacetophenone (III-1) in 85% yield.

Then, 0.9 mol of 30% sodium hydroxide was added to a mixture solution composed of 0.8 mol of the thus-obtained compound (III-1), 0.9 mol of 30% hydrogen peroxide, 0.008 mol of tetra-n-butylammonium bromide, a 2-fold amount by weight of methyl isobutyl ketone, a 2.7-fold amount by weight of water, and a 0.2-fold amount by weight of pyridine, the respective amounts being based on the weight of (III-1), at 0 DEG to 10 DEG C. over 3 hours. Stirring was continued for 3 hours at the same temperature. After completion of the reaction, the reaction mixture was rendered weakly acidic with hydrochloric acid, followed by extracting with methyl isobutyl ketone. After liquid separation, the methyl isobutyl ketone was distilled off from the organic layer to obtain 4-methylcatechol (V) in 93% yield.

Then, 0.7 mol of the thus-obtained compound (V) and 1.75 mols of sodium hydroxide were dissolved in a 5-fold amount by weight, based on (V), of water, and 1.75 mols of dimethylsulfate was added dropwise thereto at 60 DEG to 70 DEG C. over 2 hours. The mixture was maintained at the same temperature for 1 hour while stirring. After cooling, the organic layer was separated and distilled to obtain 3,4-dimethoxytoluene (VI-2) in 93% yield.

Then, 0.6 mol of the thus-obtained compound (VI-2) was dissolved in a 3.5-fold amount by weight, based on (VI-2), of carbon tetrachloride, and 0.66 mol of bromine gas was blown thereinto under reflux condition while irradiating with a mercury vapor lamp. The blowing was completed in 16 hours. After completion of the reaction, the solvent was distilled off to obtain 3,4-dimethoxybenzyl bromide (VII-2) in 92% yield.

0.5 mol of the thus-obtained compound (VII-2) was added dropwise to a 3.5-fold amount by weight, based on (VII-2), of a 50% acetic acid solution containing 0.75 mol hexamethylenetetramine over 1 hour at 20 DEG to 30 DEG C. After maintaining the mixture at the same temperature for 1 hour, the inside temperature was elevated to 105 DEG to 110 DEG C. and maintained at the same temperature for 4 hours. After completion of the reaction, the reaction mixture was poured into water, and extracted with toluene. The organic layer was concentrated, and distillation of the concentrated residue gave veratraldehyde (b.p. 155 DEG C./10 mmHg) in 75% yield.

EXAMPLE 3

0.5 mol of the compound (VII-1) synthesized in the same manner as inExample 1 was dissolved in a 2-fold amount by weight, based on (VII-1), of dimethyl sulfoxide, and a solution composed of 1.0 mol of sodium ethylate, 1.1 mols of 2-nitropropane, and a 3-fold amount by weight, based on sodium ethylate, of ethanol was added dropwise thereto at 20 DEG to 30 DEG C. over 2 hours. The mixture was maintained at the same temperature for 10 hours while stirring. After completion of the reaction, the reaction mixture was rendered weakly acidic with hydrochloric acid, poured into water, and extracted with toluene. The resulting organic layer was concentrated, and distillation of the concentrated residue gave heliotropin (b.p. 131 DEG to 134 DEG C./10 mmHg) in 65% yield.

EXAMPLE 8

1.2 mols of an m- and p-cresol mixture (m-/p-=6/4) (I-1), 2.0 mols of acetic anhydride, and 0.01 mol of pyridine were reacted for 2 hours under reflux condition. After completion of the reaction, unreacted acetic anhydride and acetic acid formed as a by-product were distilled off to quantitatively obtain cresol acetate (IV-1).

Then, 1 mol of the thus-obtained compound (IV-1) was dissolved in the same amount by weight of tetrachloroethane, and 0.8 mol of aluminum chloride was added thereto over 1 hour at 120 DEG to 130 DEG C. Thereafter, stirring was continued for 5 hours at the same temperature. After completion of the reaction, the reaction mixture was cooled to 30 DEG C., and decomposed with water. 2-Hydroxy-4- and -5-methylacetophenone (III-1) was obtained in the organic layer in 92% yield.

Then, 0.9 mol of 30% sodium hydroxide was added dropwise, at 0 DEG to 10 DEG C., to a mixture solution composed of a tetrachloroethane solution containing 0.8 mol of the thus-obtained compound (III-1), 0.9 mol of 30% hydrogen peroxide, a 2-fold amount by weight, based on (III-1), of water, and a 0.3-fold amount by weight, based on (III-1), of pyridine over 2 hours. Stirring was continued at the same temperature for 3 hours. After completion of the reaction, the reaction mixture was rendered weakly acidic with hydrochloric acid, then separated into the organic layer and the aqueous layer. The aqueous layer was extracted with tetrachloroethane, and the extract was combined with the organic layer, followed by distilling off the tetrachloroethane to obtain 4-methylcatechol (V) in 96% yield.

0.75 mol of the thus obtained compound (V) and 1.6 mols of sodium hydroxide were dissolved in a 1.5-fold amount by weight, based on (V), of water, then added dropwise to a solution composed of a 6-fold amount by weight, based on (V), of dimethyl sulfoxide and 1.8 mols of dichloromethane at 90 DEG C. to 100 DEG C. The dropwise addition was completed in 3 hours. Water azeotropically discharged during the dropwise addition was separated off. The reaction was continued for 3 hours at the same temperature. After completion of the reaction, a 2.5-fold amount by weight, based on the reaction mixture, of water was added thereto, and 3,4-methylenedioxytoluene (VI-1) was distilled out as an azeotropic mixture. Yield: 93%.

Then, 0.6 mol of the thus-obtained compound (VI-1) and 0.01 mol of benzoyl peroxide were dissolved in a 3-fold amount by weight, based on (VI-1), of chlorobenzene, and 0.84 mol of bromine gas was blown thereinto under reflux condition. The blowing was completed in 10 hours. After completion of the reaction, the solvent was distilled off to obtain a mixture of 3,4-methylenedioxybenzyl bromide (VII-1) and 3,4-methylenedioxybenzal bromide (VIII-1) in 93.5% yield.

0.5 mol of the thus-obtained compounds (VII-1 plus VIII-1) were added dropwise, at 30 DEG to 40 DEG C., to a 3-fold amount by weight, based on (VII-1 plus VIII-1), of a 50% acetic acid solution containing 0.6 mol hexamethylenetetramine over 1 hour. After maintaining at the same temperature for 1 hour, the inside temperature was elevated to 90 DEG to 100 DEG C., and maintained at the same temperature for 4 hours. After completion of the reaction, the reaction mixture was poured into water, and extracted with toluene. The organic layer was concentrated, and distillation of the concentrated residue gave heliotropin (b.p. 131 DEG to 135 DEG C./10 mmHg) in 80% yield.

EXAMPLE 9

0.5 mol of 3,4-dimethoxytoluene (VI-2) obtained by synthesizing in the samemanner as in Example 2 was dissolved in a 3-fold amount by weight, based on (VI-2), of chlorobenzene, and 0.005 mol of sodium bicarbonate and 0.01 mol of benzoyl peroxide were added thereto. Then, 0.53 mol of bromine gas was blown thereinto under reflux condition. The blowing was completed in 8 hours. After completion of the reaction, the solvent was distilled off to obtain 3,4-dimethoxybenzyl bromide (VII-2) in 92% yield.

Then, 0.4 mol of the thus-obtained compound (VII-2) was added dropwise to a 3-fold amount by weight, based on (VII-2), of dimethyl sulfoxide containing 0.5 mol of potassium hydrogencarbonate at 25 DEG to 35 DEG C. The dropwise addition was completed in 1.5 hours. Stirring was continued for 5 hours at the same temperature. Thereafter, the inside temperature was elevated to 60 DEG to 70 DEG C. to react for 4 hours. After completion of the reaction, the reaction mixture was poured into water, and extracted with diethyl ether, followed by distilling off the diethyl ether from the organic layer to obtain veratraldehyde in 82% yield.






Antoncho

java

  • Guest
Re: Patent you need
« Reply #1 on: October 08, 2003, 08:43:00 AM »
Antoncho:...this is what you may be looking for.....

Patent US4146582

as read in

Post 63189 (missing)

(Osmium: "Re: Benzaldehyde...", Chemistry Discourse)

I commend you for the summaries you've been doing , this one being no exception......java
(...and as non english first language person I have problems with spelling and having said that .......Jucy>>>>>juicy)


Antoncho

  • Guest
Thank you, Java...
« Reply #2 on: October 08, 2003, 10:27:00 PM »
... this IS the patent i've been looking for!


... as for the summaries - noone would read those patents otherwise ;D  so i sorta have to do it :)



Yours,

A-cho

GC_MS

  • Guest
comments
« Reply #3 on: October 09, 2003, 01:58:00 PM »
2. Dakin oxidation (with NaOH/H2O2) of the hydroxy-acetophenone to catechol: never seen this rxn work on acetophenones bee4, only on aldehydes.

Dakin has pretty much in common with the Baeyer-Villiger oxidation reaction, which works with acetophenones as well. I must say that the yield is rather (suspiciously?) high though.

Also, did the compound 2-methyl-4,5-methylenedioxyamphetamine spook through your mind?  ;)


Rhodium

  • Guest
6-Methyl-MDA is unfortunately inactive...
« Reply #4 on: October 09, 2003, 02:30:00 PM »

Synthesis and Pharmacological Evaluation of Ring-Methylated Derivatives of 3,4-(Methylenedioxy)amphetamine (MDA)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/nichols/nichols-ring-methylated.mda.pdf)

"Most apparent from the data is the fact that [2-Me-MDA/5-Me-MDA/6-Me-MDA] are almost completely inert at the dopamine uptake carrier, being more than 10 times less potent than MDA [...]"

"[6-Me-MDA] shows reduced activity at the 5-HT carrier as well, being only about one-half as potent as [MDA].

"As would be expected from an examination of the uptake inhibition data, none of the compounds substituted [in trained rats] for the catecholamine releaser (+)-amphetamine. [2-Me-MDA/5-Me-MDA] substituted completely for both (+)-MBDB and MMAI and were slightly more potent than MDA in the (+)-MBDB-trained rats, whereas [6-Me-MDA] exhibited only partial substitution in (+)-MBDB-trained rats and substituted in MMAI rats only at a relatively high dose."

"[6-Me-MDA] is once again only marginally active, showing partial substitution at high doses in DOI- and LSD-trained rats. Thus, [2-Me-MDA/5-Me-MDA] but not [6-Me-MDA], retain the hallucinogen-like behavioral effects of the parent compound presumed to be mediated by the 5-HT2A receptor."

"In summary, both the in vitro and in vivo data point to [2-Me-MDA/5-Me-MDA] as serotonin-releasing agents more potent than MDA, with [5-Me-MDA] appearing to be slightly more potent than [2-Me-MDA] in most of the assays. These data indeed support our conjecture that in [2-Me-MDA], as well as [5-Me-MDA], the amine side chain can assume a favorable conformation for interacting with the serotonin carrier, whereas in [6-Me-MDA] the side chain is forced into an unfavorable position. Further support for this idea was provided by a conformational analysis employing semiempirical AM1 potential functions [...]"



Pihkal #98 MADAM-6 (2,N-Dimethyl-4,5-Methylenedioxyamphetamine)

(http://www.erowid.org/library/books_online/pihkal/pihkal098.shtml)

DOSAGE: greater than 280 mg.
DURATION: unknown.
QUALITATIVE COMMENTS:
(with 180 mg) There is a hint of good things there, but nothing more than a hint. At four hours, there is no longer even a hint.
(with 280 mg) I took 150 milligrams, waited an hour for results, which was niente, nada, nothing. Took supplements of 65 milligrams twice, an hour apart. No effect. Yes, we giveth up.

EXTENSIONS AND COMMENTARY: How fascinating it is, that a small methyl group, something that is little more than one more minor bump on the surface of a molecule that is lumpy and bumpy anyway, can so effectively change the action of a compound. A big activity change from a small structure change usually implies that the bump is at a vital point, such as a target of metabolism or a point of critical fit in some receptor site. And since 6-MADAM can be looked upon as 6-bump-MDMA, and since it is at least 3x less potent than MDMA, the implication is that the action of MDMA requires some unbumpiness at this position for its particular action.

Megatherium

  • Guest
Translation request
« Reply #5 on: May 20, 2004, 06:48:00 AM »
Shall i remind that there are some other ways of turning a toluene into a benzaldehyde: the most ecological one is undoubtedly refluxing it with an xcesss of activated MnO2 in heptane or some high-boiling naphtha (3-4 hrs, intensive stirring). That's Assholium's favorite method,

Post 429514 (missing)

(Assholium: "åñòü êàêèå-òî ìûñëè?", Russian HyperLab)


It would be appreciated when a russian bee could translate the procedure  ;) .

Want to compare it with

Post 244957

(Chemikaze: "Benzaldehyde via MnO2 oxidation of toluene", Novel Discourse)

psyloxy

  • Guest
toluene to 3,4-dihydroxytoluene
« Reply #6 on: May 20, 2004, 03:55:00 PM »
preparation of p-cresol
Toluene, Cu(NO3)2, H2O2, phosphate buffer __> para-cresol in 89% yield. it's in Organic Preparations and Procedures International, 32(4), 373-376 (2000). which is available as .pdf in

Post 499541

(Rhodium: "Archive of "Wanted References" Volume 2", Novel Discourse)



In a typical experimental procedure, to a solution of anisole (1.08g, 0.01 mole) in acetonitrile (10mL), was added neutral phosphate buffer (997mg, 3.6 mmoles) in 10 mL of water, cupric nitrate (0.5g, 2.1 mmoles) in 2 mL of water follewed by the addition of 30% H2O2 (7mL, 0.0618 mole) in three portions. The reaction mixture was heated at 50°C for 4hr. After completion of the reaction as indicated by TLC, the reaction mixture was diluted with water (10mL), extracted with ethyl acetate (15mL). The organic layer was washed with water, dried over Na2SO4 and the solvent was evaporated under reduced pressure. The crude product was chromatographed over silica gel column using chloroform:ethyl acetate (3:1) as eluent to yield pure products 1.165g (94%), which was analysed by HPLC as 1.104g (89%) of p-hydroxyanisole and 0.136g (11%) of o-hydroxyanisole.

Reaction conditions for toluene as substrate: time: 4h, yield: 95%, yield of p-isomere:94%, mp201°C

preparation of 3,4-dihydroxytoluene

Patent DE81298


3Kg K2S2O8 are gradually introduced to a solution of 1,3kg para-cresol and 2,5kg NaOH in 75Kg H2O. This is allowed to stand 1 to 2 days at room temperature or 40°C. Then carbonic acid is introduced, unchanged para-cresol is extracted with Et2O, the residue is boiled with HCl and the 3,4-dihydroxytoluene extracted with Et2O.

--psyloxy--

azole

  • Guest
Re: Translation request
« Reply #7 on: May 21, 2004, 10:20:00 AM »
...

Post 429514 (missing)

(Assholium: "åñòü êàêèå-òî ìûñëè?", Russian HyperLab)


It would be appreciated when a russian bee could translate the procedure.  ;)


   Actually, Assholium has not posted an exact procedure for the preparation of aromatic aldehydes. He just made a suggestion that 4-methyl-3-nitrobenzaldehyde can be prepared by selective oxidation of 1,4-dimethyl-2-nitrobenzene. Here is the translation:

   Nitrate p-xylene. Dissolve the nitro compound in heptane and oxidize it by active manganese dioxide at 100° with vigorous stirring (3-4 h). Only the methyl located meta- to the nitro group should be oxidized. The one in ortho-position won't be oxidized because it is deactivated by the nitro group. Cool the mixture, dilute it with equal volume of dichloromethane and filter off the manganese oxides. Distill off the DCM and refrigerate the residue. On cooling the heptane solution, the aldehyde should crystallize out.

   The point is that we don't lose anything. Both dichloromethane and heptane can be reused for another oxidation of nitroxylene.

   Active manganese dioxide can be made simply. Add a hot potassium permanganate solution to a hot solution of manganese sulfate. The mixture gradually becomes colorless, and a brown precipitate falls out. Filter it off, wash with water, and dry. The reagent is ready.




Wraith

  • Guest
Methylenation without KF or PTC
« Reply #8 on: May 22, 2004, 09:59:00 AM »
The methylenation procedure in which polymerization is inhibited by controlling the concentration of the dihydroxybenzene dianions is not that novel at all, see

https://www.thevespiary.org/rhodium/Rhodium/methylenation.bonthrone-cornforth.html



SWIM had a really interesting dream one night, he thought he would like to share it with the bees. In his dream he saw an man wearing a white lab coat doing the following things:

A 250 mL three-neck RBF was fitted with a reflux condenser and a thermometer. The third neck is stoppered with a rubber stopper for addition of solid. The flask is charged with 12.5 g anhydrous Na2CO3, 13 mL CH2Cl2 (260% excess), 27.5 mL DMF and 0.5 g anhydrous NaI to act as a nucleophilic catalyst.

This mixture is heated to boiling (75 C) on a water bath and 6 g of 5-hydroxyvanillin (recrystallized from boiling toluene; Note 1) is added over 3 h, the reaction mix is heated for 6 h more, then an additional 4 g of 5-hydroxyvanillin is introduced during a period of 3 h (Note 2) Heating is continued for 12 h (total reaction time 24 h). The internal temperature rises gradually, reaching 98-100 C by the completion of the addition of substrate and staying there for the rest of the reaction time.

The flask is cooled, reaction mixture (black in color) diluted with water, a little dil. NaOH added and extracted 4x with CH2Cl2. The extracts are washed with water, 2x with dil. NaOH, then again with water. The extracts are dried on MgSO4 and solvent is distilled off leaving a black residue that crystallizes in the flask. This is dissolved in hot ethanol (100 mL), filtered through a fluted filter paper from some insolubles and cooled in the freezer. The crystals are separated and the mother liquor concentrated. Total yield: 5.8 g, 53% of light brown myristicinaldehyde, mp 129-131 C (pure enough for practical purposes, another recrystallization from ligroin affords off-white crystals having mp. 131-133 C, downside is that 100 mL 80-100 C ligroin dissolves less than 2 g of aldehyde)

The old man seemed to mumble to himself in SWIM's dream, this is what he could understand:

Note 1. Unrecrystallized black tarry 5-OH-vanillin has been used successfully, the reaction solution however must be filtered from some tar after dilution with H2O.

Note 2. The old man's actual plan was to add the entire 10 g over 8 h but he fell asleep after 3 h.

Sorry if this is old news. Nonetheless it's a convenient and quite OTC procedure as KF is watched in many countries and so are PTC's. The yield certainly could be improved.

1. PiHKAL #134 (MMDA-3a)
2.

https://www.thevespiary.org/rhodium/Rhodium/methylenation.bonthrone-cornforth.html





Wraith

P.S.: Can anyone provide SWIM with the vapour pressure of myristicinaldehyde at 100 C, or empirical data on how much steam is needed per g when doing a steam distillation?