demorol
(Hive Bee)
07-01-02 02:54
No 327547
      Protocatechualdehyde preparation
(Rated as: excellent)
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Two nice patents about protocatechualdehyde preparation were found on Espacenet.

Process for preparing protocatechualdehyde and its derivatives Patent US4165341

Abstract
A process for preparing protocatechualdehyde or a 3-alkoxy-4-hydroxybenzaldehyde which comprises subjecting catechol or a 2-alkoxyphenol to reaction with glyoxylic acid in a basic aqueous medium in the presence of a catalyst containing one or more compounds selected from aluminium oxide, silicon oxide and hydrated aluminium oxide in an amount of not less than 0.01 g per 1 g of the starting catechol or 2-alkoxyphenol at a temperature of 0 to 50 C, and then oxidizing the thus obtained reaction mixture in a basic medium.

Process for preparing protocatechualdehyde Patent EP0786446

Abstract
Protocatechualdehyde is prepared by the steps of reacting piperonyl dichloride with molecular chlorine in the presence of phosphorus trichloride, phosphorus pentachloride or sulfuryl chloride to prepare dichloropiperonylidene dichloride and hydrolyzing the dichloropiperonylidene dichloride. The piperonyl dichloride can be prepared by the reaction of piperonal with thionyl chloride in the presence of DMF.

Life without chemistry would be a mistake.
 
 
 
 
    ChambeRed
(Hive Bee)
11-07-02 18:34
No 377508
      Could anyone possibly help me with mabey a ...  Bookmark   

Could anyone possibly help me with mabey a skeleton procedural for the top abstact for producing protocatechualdehyde from pyrocatechol.I would like to try this possibly,I'm a newbee so that abstact kinda leaves me in the dark but this is what I'd do if for some reason I absolutely had to without anything else to go on(or a clue what i'm doing)

Prepare a solution of 150g. catechol dissolved in 200ml dh20 and pour into addition funnel.In a 3-neck 2000ml fbf is placed??250g.glyoxylic acid in 500ml 10%NaOH solution?? then add 8g. aluminum oxide(that would be my choice if all are equal)and add reflux condenser(I don't think a condenser is needed none of the rxn components have b.p's below 50c?)the other two necks are plugged with (1)a thermometer submerged in the flask contents to monitor temp.
(2)the addition funnel with catechol/dH2O solution
contents of addition funnel added at a rate to keep the temp from rising above 50c(also not sure if the additon is even needed,mabey just place the flask in a plastic tray and add the catechol all at once and then just add icewater as needed??)
Let this stir for??3hrs. after addition is complete??, unless rxn is still noticeably going then just let it stir until at least an hour after it has died down.
Totally lost here?guess i'd pour the contents of the rxn flask into a 25%NaOH solution stir the shit out of it for awhile and extract the whole shebang with Ether or DCM.
And if that didn't work next time i'd try a mild reflux for a few hrs with 25%NaOH solution.
And if that didn't work i'd try adding concentrated NaOH solution to the mix slowly and see what happens.
And if that didn't work.....well guess i'd bee screwedsmile.Any comments on any aspect of the reaction or any comments at all would be very appreciated,Thanks!smile.Peace,Chambered.

Bee's don't die,we just multiply.
 
 
 
 
    starlight
(Hive Bee)
11-08-02 02:39
No 377635
      oxidation step  Bookmark   

I haven't read what you have proposed in detail, but have read it enough to see that you have missed the oxidation step described in the patent (have another look at the patent).

In the patent they suggest that this oxidation step be done with CuO in an autoclave, so not sure how far you will get on this one (i.e. if there is a way to do the oxidation without autoclave).
 
 
 
 
    ChambeRed
(Hive Bee)
11-09-02 10:20
No 378109
      Thanks starlight,where are you seeing anything ...  Bookmark   

Thanks starlight,where are you seeing anything about CuO or an autoclave?I've looked up the patent and I don't see any more than whats in the top abstact above.Peace,Chambered.

Bee's don't die,we just multiply.
 
 
 
 
    starlight
(Hive Bee)
11-11-02 02:18
No 378649
      you need to look at more than page 1  Bookmark   

there are several pages to the patent. I have looked at it on gb.espacenet.com. you probably have not clicked through far enough.
 
 
 
 
    ChambeRed
(Hive Bee)
11-11-02 02:31
No 378653
      Thank you,I tried to find more but apparently I ...  Bookmark   

Thank you,I tried to find more but apparently I was clicking the wrong button cause it wouldn't show me anymoretongue.Now that I know for sure there is more I can be a little more persistent in finding itsmile.Thanks,Chambered.The many,many synthetic routes available when one starts with an essentially scratch molocule like catechol is mind-boggling and chemistry at its best imho.Thank you kindred spirits,for helping me see what life CAN beesmile.

Bee's don't die,we just multiply.
 
 
 
 
    ChambeRed
(Hive Bee)
11-12-02 10:14
No 378995
      I feel like a moron and probably am but how do ...  Bookmark   

I feel like a moron and probably am but how do you view the other pages?when I follow the link above it says page 1 of 1 and I've clicked on practically everything clickable to no avail.Help pleaseblush.

Bee's don't die,we just multiply.
 
 
 
 
    Rhodium
(Chief Bee)
11-12-02 15:22
No 379061
      Alternative patent search  Bookmark   

Go to http://patft.uspto.gov/netahtml/srchnum.htm and type in the US patent numbers 4165341 or 5696301 to see them. If you want to see the patent images too, click the "images" link at the top of the page.
 
 
 
 
    ChambeRed
(Hive Bee)
11-12-02 19:09
No 379148
      Thanks chief that made an elightning read.  Bookmark   

Thanks chief that made an elightning read.The patent states that oxidation can be done at either atmospheric or under pressure,I imagine a good comprimse could be a regular pressure cooker(used for canning)with mag. stirring.Overall I think this sounds not too bad with good yields and selectivity(bolth over 90% in patent),all though it's not as eaisy as the Riemer-Tiemann reaction outlined in TSII but yields are better and probably selectivity as well.

Bee's don't die,we just multiply.