novel synthese of trimetoxybenzaldehyde

[freakyDMT]

bees, i found anvery interesting patent about the direct synthese of 3,4,5-trimethoxybenzaldehyde from 5-bromovanilline.
the number of the patent is

Patent US4933498

[amine]

ain't so novel check out Rhodium's website under the  mescaline. The biggest problem most bees have with this synthesis is the DMS which is both carcinogenic, toxic and most bees like myself cannot obtain this.

Generally its vanillin--->bromo/iodo-vanillin ---> hydroxyvanillin ----> 3,4,5 trimethoxy.

I'm sure if u have a fume hood you can make this much easier. most bee's however are out of luck .

[psyloxy]

This is revolution in progress:

Post 417550

(Antoncho: "Methyl tosylate: _finally_ , OTC!!!", Novel Discourse)

Post 257912

(Antoncho: "Alkali metal alkoxides: finally, OTC!", Novel Discourse)

--psyloxy--

[yellium]

The biggest problem most bees have is not overoxyidizing the aldehyde. That, and preparing a 5M sodium ethoxide solution.

[psyloxy]

In my sleep-deprived numbness I ask: where on the way from vanilline to 345-TMBA could overoxidization occur ? Or do you mean generally by working without an N₂/Ar atmosphere ? As to the 5M NaOEt solution: do you have a remedy for that lack of know-how ?

--psyloxy--

[yellium]

5M sodium ethoxide/methoxide solutions aren't solutions anymore; they are some kind of slurry. Ever tried to stir a slurry? Ever tried to dissolve a workable amount (say, 10 g.) of bromovanillin in a slurry like that?

Regarding the overoxidation: UTFSE, and yes, O2 is the main culprit. When you work on a small scale, it's easy to end up with a nice amount of benzoic acid instead of your aldehyde. You also have some fair chances of fucking things up during workup (at least when your solutions are still basic).

Now, if you want to work with 3,4m5-trimethoxybenzoic acid, that's easy to get. No need to do a 3-step reaction to get that.

[hypo]

have you guys read the patent? the novel thing is that it's
a one pot solution. all examples are with MeCl and with pressure,
but it claims 1 bar and other MeXs too. of course you end up
with a considerable amount of dimethoxy benzaldehyde too, which
has to be separated somehow. (vacuum distillation?)

ps: what have alkoxides to do with this? and doesn't hest's DMF
method use much thinner solutions?

[hest]

Ohh yes, and it works  

[yellium]

Care to explain the pitfalls (or, do's and don't's) for us chem-weenies?

[Rhodium]

For the record, I assume that we are talking about

Post 189401 (missing)

(hest: "Re: 3,4,5 Trimethoxybenzaldehyde Synth", Chemistry Discourse), right?

[yellium]

Yup. And I wonder how you can add a solution of 17.9 g bromovanillin in 50 mL of DMF to a 'solution' of 5 gr Na in 70 mL MeOH. Under nitrogen. In my experience, you need way more DMF to dissolve the bromovanillin than 50 ml.

Also, I think you can't 'pure outh' the reaction mixture on HCl/ice, since you've distilled almost all solvent away. Instead, you might add 200 ml ice-cold HCl with a Schlenk addition funnel.

[hest]

Yup. And I wonder how you can add a solution of 17.9 g bromovanillin in 50 mL of DMF to a 'solution' of 5 gr Na in 70 mL MeOH. Under nitrogen. In my experience, you need way more DMF to dissolve the bromovanillin than 50 ml.

Not a problem. The aldehyde is quite sol. in DMF.

Also, I think you can't 'pure outh' the reaction mixture on HCl/ice, since you've distilled almost all solvent away. Instead, you might add 200 ml ice-cold HCl with a Schlenk addition funnel.  

You still have some liquid (100mL MeOH +50mL DMF = 150mL     150mL-80mL=70mL). Those 70mL is pored out in the Hydrochloric acic/ice mixture. The synt have been done in 10 and 100g scale's

[yellium]

Not a problem. The aldehyde is quite sol. in DMF.


IIRC, I needed something like 150 ml to get it to dissolve. Don't know why. Is vanillin (or the dibromo-aldehyde) less soluble in DMF? Also, could there be a possibility that the aldehyde forms poorly (DMF-)soluble hydrates?

[hest]

Hi Yellium, I'ts some time since I have made the synth, but ill look into it.