Sciencemadness Discussion Board - Glyoxal Synthesis

Glyoxal Synthesis

The_Davster - 2-9-2005 at 08:38

For Acquisition, contact your favorite photography supplier and ask them to get it for you, it is slowly replacing formaldehyde as it is less toxic, some suppliers already have it in stock.

[Edited on 5-9-2005 by chemoleo]

vulture - 2-9-2005 at 10:09

Glyoxal synthesis reportedly works through careful oxidation of ethanol with HNO3. That's all I have, maybe somebody can dig up a patent on that one.

EbC: Context

[Edited on 5-9-2005 by chemoleo]

IPN - 2-9-2005 at 10:41

Here is what Ullmann says about Glyoxal synthesis:

Quote:

From Acetaldehyde. Oxidation with nitric acid was examined by LJUBOWIN as early as 1875 and patented in 1942 BF885931. Reaction takes place at ca. 40 °C and is carried out industrially as a continuous process. Maximum yield is ca. 70 %; selectivity is a function of the relative concentrations of reagents. After the removal of excess acetaldehyde, the glyoxal formed, which is contaminated with acetic, formic, and glyoxylic acids, is purified by passage of the aqueous solution through an ion-exchange resin. The solution is then concentrated to a glyoxal content of about 40 %.
Selenium oxide is more selective than nitric acid, and the yield is ca. 84 %; the selenium can be recycled by oxidation with hydrogen peroxide FR2038575. This process has not been carried out on an industrial scale.
From Ethylene Glycol. The gas-phase oxidation of ethylene glycol by atmospheric oxygen in the presence of dehydrogenation catalysts (metallic copper or silver) represents the basis of the Laporte process GB1272592 and has been used in several industrial production processes. Reaction occurs between 400 and 600 °C; the yield is 70 – 80 %. The main impurity is formaldehyde , whose subsequent separation is difficult. This reaction has also been carried out in the liquid phase and under irradiation.
Other Processes . Ethylene can be oxidized by aqueous nitric acid in the presence of palladium DE1166173, by atmospheric oxygen, or by selenium oxide deposited on silica. Glyoxal may also be formed by oxidation of acetylene GB1071902 or benzene US3637860 with ozone. Ethylene oxide has been proposed as a substrate for oxidation. Although oxalic acid and its derivatives can be reduced to glyoxal, these processes have not been developed further.

Here is the orgsyn.org's synthesis of glyoxal

[Edited on 2.9.2005 by IPN]

S.C. Wack - 2-9-2005 at 12:03

Vanino details the procedure from aq. acetaldehyde/HNO3, citing 6 articles. No mention of yield, but I would bet that it isn't high.

Gallica's Beilstein 1, 786 cites the earliest of the 6, Ber. 10, 1365 (1877) - but yield in this ref really sucks, this is improved upon in abstracts of the Russian articles such as Ber. 14, 2685 (1881). Beilstein also abstracts using paraldehyde instead, from Bull. Soc. 41, 242.

Also in German, DE573721.

Interesting choice of thread title.

The_Davster - 2-9-2005 at 20:34

Could there possibly be a electrochemical route to glyoxal? Anyone have the electrical potential for the oxidation of ethylene glycol to glyoxal? Or the potential for the reduction of oxalic acid to glyoxal?

Yes I know its a long shot...

[Edited on 3-9-2005 by rogue chemist]

More on glyoxal synthesis & properties

chemoleo - 5-9-2005 at 15:05

Yes, in Bayer/Walter it says that the oxidation to glyoxal can be achieved with HNO3 due to the removal of glyoxal as the di-bisulfite addition product.

Else, with paraldehyde and selenium dioxide (Rabjohn, Selenium Dioxide Oxidation, Org. Reactions 5, p.331 (1949)).
Methylglyoxal can be similarly made with SeO2, but from acetone - which is readily accessible (unlike acetaldehyde/paraldehyde), while the methylglyoxal is propably almost as useful for many reactions.

Glyoxal is also the most simple organic AND coloured compound (it forms yellow prisms, with green vapours and melts at 15 deg C, and burns with a violet flame), and is the dihydrate in water. It polymerises easily to colourless polyglyoxal, which can be depolymerised with P2O5 at heat.

PS Rogue, re. electrochemical reduction/oxidation, is there evidence in the literature anywhere, with simple alcohols?
The question is how oxidation onwards to oxalic acid is prevented. I should think that this would be very tricky, as (if the oxidation is a random process), you will also get CHO-CH2OH, HOOC-CHO and (COOH)2 of course, while CHO-CHO is only one of the possible products.

[Edited on 5-9-2005 by chemoleo]

The_Davster - 5-9-2005 at 19:19

Yes Chemoleo, I really believe it can be done. (I have a bit of an electrochem obsession going currently

). According to "manufacture of chemicals by electrolysis" superimposing AC on DC current allows for the preparation of compounds not normally easily prepared by electrolysis. "ethyl and propyl alcohols give the corresponding aldehydes whereas when oxidized by continous current only, the principlal product is the corresponding acid" I imagine this can be done with ethylene glycol as well to get glyoxal, but unfortunatly no info is given about electrode types

. Interesting to note that superimposing AC on DC also gives more ozone when electrolysing dil. H2SO4, and can be used to make benzaldehyde and benzoic acid from toluene when with just DC CO2 is produced. I really want to experiment with these methods of electrolysis, and am gathering the parts for a proper power supply. If anyone can gather any journal entries about these methods of electrolysis please post them here.

Its a great file that pdf...even some stuff on electrolytic diazotizations. :cool:

[Edited on 6-9-2005 by rogue chemist]

Phel - 1-6-2006 at 18:02

Quote:

Originally posted by rogue chemist
Could there possibly be a electrochemical route to glyoxal?

Perhaps an OTC electrochemical road to glyoxal:

Quote:

The electrochemical oxidation of maleic acid on tungsten anodes has been investigated. Glyoxal and carbon dioxide were the main products together with tartaric acid and acetaldehyde. Glyoxal is also obtained as the main product from the oxidation of d-tartaric acid. Under the same conditions succinic acid is completely oxidized to carbon dioxide and water.

Ref:
Journal of Applied Electrochemistry
SSN: 0021-891X (Paper) 1572-8838 (Online)
DOI: 10.1007/BF01112074
Issue: Volume 12, Number 1
Date: January 1982
Pages: 127 - 133

(sorry about the bump

)

The_Davster - 2-6-2006 at 17:00

Hmm the last few lines of the article do not bode well, seems there is an annoying oxide layer which builds up on the electrode, hindering further oxidation of the tartaric.

Eh, I'll get some tartaric acid soon hopefully and give this a shot.

They seem to imply at one point that tungsten is not necessary, and that other electrode materials give impure results. The reference for it is from "Ann. Acad. Sci. Fenn". What is that without abbreviations so I can look it up?

Phel - 2-6-2006 at 17:36

I believe what you are looking for is "Annales Academiae Scientiarum Fennicae". Looking forward to hear your results!

stygian - 11-6-2006 at 13:29

The Org. Syn. Page says it can also be made by hydrolysis of dichlorodioxane. Would this be the same dichlorodioxane formed from dioxane/TCCA/iodine? Ethylene glycol + H2SO4 yields dioxane if I recall correctly.

The_Davster - 11-6-2006 at 13:34

That is OTC but it involves way too nasty precursors to make it useful. Frogfot has the dioxane synth you mention on his page.

I have been unable to find the reference I mentioned earlier. The article must have wrote it down wrong. I am still waiting on my tartaric acid, hopefully I find time to try this once I get it.

Mason_Grand_ANNdrews - 14-6-2006 at 09:37

I guessing a cheap glyoxal synthesis is most attractive.

I have searched sometimes the web, but i can`t found somewhat about the glyoxal hydrate synthesis.

A reported link

is helpful for me.

acetate - 16-6-2006 at 15:09

Quote:

Originally posted by Phel

Ref:
Journal of Applied Electrochemistry
SSN: 0021-891X (Paper) 1572-8838 (Online)
DOI: 10.1007/BF01112074
Issue: Volume 12, Number 1
Date: January 1982
Pages: 127 - 133

Attachment: j7n274305v3h0272.pdf (513kB)
This file has been downloaded 2351 times

scientistfromdarkness - 26-6-2006 at 09:23

Why to synthesize when you can buy it from Sigma-Aldrich. It is not expensive

Eclectic - 27-6-2006 at 09:23

Why cook when you can have fast food?

guy - 11-2-2007 at 01:43

Oxidation of ethylene glycol in gas phase with copper oxide (~300oC) yields glyoxal.

Source

Quote:

Two well established processes employed for the production of glyoxal are the gas-phase oxidation of ethylene glycol with air in the presence of copper or silver catalysts at elevated temperature (about 300 °C) and the liquid-phase oxidation of acetaldehyde with nitric acid (Chumbhale & Awasarkar, 2001).

[Edited on 2/11/2007 by guy]

not_important - 11-2-2007 at 03:06

The alcohol (or glycol) and air oxidation over copper or silver is a little tricky, as the gas mixture has flammible and explosive ranges for oxygen content wanted for good conversion - be careful with that.

Just running the alcohol over Cu or Ag will give some aldehyde formation CH2OH => H2 + CHO. Not as good as when oxygen/air is added to removed hydrogen and for the reaction but often acceptable.

For a batch mode process, copper oxides can be used in place of metallic copper. The alcohol/glycol reduces the oxide, which functions as an oxygen source less likely to give annoying flashback and explosive pops. The oxide can be regenerated by passing air over the copper while heating it.

Sauron - 11-2-2007 at 03:08

The Org.Syn. prep uses selenous acid and explains why it was preferred to the oxide. Acetaldehyde as paraldehyde is the starting material, and it is done on a scale that yields c.350 g of the bisulfite addn cpd.

The procedure is attached as a pdf

[Edited on 11-2-2007 by Sauron]

Attachment: CV3P0438.pdf (129kB)
This file has been downloaded 2166 times

Sauron - 12-2-2007 at 11:14

Serendipity Happens

The nice thing about having electic interests in chemistry is that sometimes when you are hunting through the lit. for one thing, something else completely different but still of great interest jumps off the page at you.

This just happened to me. I was reading a JACS communication that is related to my novichok lit.search and found that the authors had been misreferenced as those of the immediately following article on same page.

The adjacent article is:
A New Synthesis of Glyoxal Tetramethyl Acetal
Ralph C. Schreyer
JACS 73 pp 2962 - 2963 (1951); DOI: 10.1021/ja01150a535

The DuPont authors describe chlorination in the cold of 1,2-dimethoxyethylene to give the tetramethylacetal of glyoxal in high yield.

MeOCH=CH0Me + Cl2 -> (MeO)2C-C(OMe)2

I have not checked into the availability of the starting material yet, I came straight here to post.

Article is attached below, Enjoy!

[Edited on 12-2-2007 by Sauron]

Attachment: glyoxaltetraMeacetal.pdf (306kB)
This file has been downloaded 1749 times

Sauron - 12-2-2007 at 11:38

Aldrich does not have this starting material, but here is a link to Springer Verlag and a Russian article on this kind of compound (ethers of 1,2-ethenediol)

http://www.springerlink.com/content/j1221718j8514847/

adi54 - 15-2-2007 at 22:19

3%0% solution of Acetaldehyde is to be reacted with 61% nitric acid using small pinch of Sod. Nitrite at 40-43deg cel . reactin is instatanious only thing is you have to add Nitric acid at 40 deg to start reaction then this is exothermic and is to be cooled to maintain temp.

Reaction product is Distilled under vacuum to remove dil acetic acid and concentrate is to pass through Weak Anion resin and reconcentrated under vac to 40% Sp gr 1.27.

But what you are going to use this in pl do let us know .

Sauron - 15-2-2007 at 22:48

@adi54, please edit your post.

Who are you replying to?

Do you mean 30% acetaldehyde, you wrote 3%0%

This looks like a glyoxal prep but my post immediately above concerned 1,2-ethenediol and the conversion to glyoxal tetramethylacetal.

Please clarify.

adi54 - 16-2-2007 at 02:42

Sorry it is 30.0% acetaldehyde and since the thread was for Glyoxal I did not clarify , sorry for the touble

Sauron - 16-2-2007 at 05:08

No problem, it's a useful prep since many will prefer HNO3 to selenium oxide.

quino - 16-2-2007 at 05:14

http://138.23.152.128/protocols/Preparing%20glyoxal.pdf

http://www.springerlink.com/index/L351W055X3WL48M0.pdf

Preparation of glyoxal by the action of acetylene on gold chloride or gold bromide

Kindler, Karl

Berichte der Deutschen Chemischen Gesellschaft [Abteilung] B: Abhandlungen (1921), 54B, 647-9

The Au is quant. pptd. by C2H2 from aq. solns. of its halides containing not much more than 1.5% Au; the org. products are only glyoxal and small amts. of CO2; the finely divided Au can again readily be converted into its halides by means of Cl or Br. The C2H2, purified according to Gottig's directions (Ber. 32, 1877(1899)) and, to free it from any AcH which might have been formed, further washed with 30% NaHSO3 and then with 30% NaOH, was passed into 2.6 g. of the Au halide in 100 cc. H2O at 70-80° in a flask connected with a condenser, cooled receiver and NaOH wash bottle protected from atm. CO2 with sodalime. With a moderate stream of C2H2, the reaction is complete in about 2 hrs. The yield of CO2 was about 12%; no AcH could be detected in the receiver. The filtrate from the pptd. Au with PhNHNH2 in dil. AcOH gave 86% of glyoxal osazone, m. 169-70°.

[Edited on 16-2-2007 by quino]

quino - 16-2-2007 at 05:38

Preparation of stable glyoxal

PATENT NO. FR 1342537

Acetaldehyde (I) (50%) and 40% HNO3, each dild. with deionized H2O in a molar ratio of 2.5:1 were charged continuously with stirring into the top of one reactor at 38-9° and withdrawn from the bottom of a second reactor at the same temp. A little NO2 was introduced into the first reactor as an initiator. Reaction time in each reactor was about 3 hrs. A feed of 11 parts I and 6.74 parts HNO3 gave 39.2 parts aq. mixt. contg. 9.1% glyoxal (II), 6.3% org. acids, 1.4% HNO3, and 16.5% I. This aq. mixt. was concd. at 50° and 50 mm. until HNO3 reached 5% and heated further at 50° for 2 hrs. after addn. of 0.6 part I to consume remaining HNO3. The mixt. was then passed through an anion exchanger to yield 8.9 parts soln. contg. about 40% II and less than 0.8% org. acids. This soln. was passed through a cation exchange column (0.6 part acid type resin) and shelf stored at 35-40° for two months with no discoloration. A similar soln. prepd. with crude HNO3 and non-purified H2O and not treated by cation exchange was yellowish brown in only two weeks.

quino - 16-2-2007 at 05:42

Preparation of pure glyoxal

Brudz, V. G.; Drapkina, D. A.; Markovich, I. S.

Sb. Statei, Vses. Nauchn.-Issled. Inst. Khim. Reaktivov i Osobo Chistykh Khim. Veshchestv (1961), (No. 24), 98-101

Glyoxal (I) was prepd. by the action of oleum on Cl2CHCHCl2 (II). Optimal 71.5% yields were achieved when II was added dropwise during 1.5 h. to 15% excess H2SO4 contg. 60 .+-. 2% SO3 in the presence of 0.15% HgCl2 and heated 3.5 h. at 58-60°. Glyoxal sulfate (III) was filtered from the cooled mixt. which contained chlorosulfonic acid. An aq. soln. of III was treated with CaCO3 to free I and ppt. CaSO4.

quino - 16-2-2007 at 05:45

Glyoxal preparation

Toyoda, Yoshiaki;
Patent Information

US 4555583 A
(CHO)2 (I) was prepd. in high yield and with very little formation of HOCH2CHO as the reaction intermediate, by gas phase oxidn. of HOCH2CH2OH (II) at 450-650° in presence of a Ag (particle size 1 .times. 10-3 mm) catalyst and a P compd. Thus, a reactor contg. Ag and tri-Et phosphite, and charged with II, steam, air, and N at 502° resulted in 100% conversion of II, a I selectivity of 80.1%, HCHO selectivity of 2.1% and HOCH2CHO of trace amt.

quino - 16-2-2007 at 05:49

Continuous preparation of glyoxal

Sauer, Wolfgang; Hoffmann, Wolfgang
Patent Information
PATENT NO. DE 2922599 A1 The product gases (450-800°) from glyoxal prepn. (by oxidn. of glycol over Ag) were quenched (after at most 1 s after leaving the catalyst) with droplets (0-130°) of H2O or aq. glyoxal entering at an angle of 2-85° with the stream axis. Several examples were given in terms of numbered app. diagrams.

quino - 16-2-2007 at 05:50

Preparation of glyoxal, alkylglyoxals, and their acetals

PATENT NO.
AT 379799 B
The title compds. RCOCHO and RCOCH(OR1)2 (R = H, C1-6 alkyl; R1 = C1-6 alkyl) are prepd. by the ozonolysis of RC(:CH2)CH(OR1)2 at -80° to 0°, followed by hydrogenation of the ozonolysis product at pH 2-7 while keeping the peroxide content .ltoreq.0.1 mol/L. Thus, H2C:CHCH(OMe)2 in MeOH was ozonolyzed at -15 to -10° and the product hydrogenated over Pt (prepd. in situ by the redn. of PtO2) at pH 2-4. The stream of H was regulated in such a way as to keep the peroxide content .ltoreq.0.02 mol/L. The product was purified by ion exchange and rectification, to give 81% OCHCH(OMe)2.

quino - 16-2-2007 at 05:52

Glyoxal preparation

Toyoda, Yoshiaki;
PATENT NO.
US 4555583 A
(CHO)2 (I) was prepd. in high yield and with very little formation of HOCH2CHO as the reaction intermediate, by gas phase oxidn. of HOCH2CH2OH (II) at 450-650° in presence of a Ag (particle size 1 .times. 10-3 mm) catalyst and a P compd. Thus, a reactor contg. Ag and tri-Et phosphite, and charged with II, steam, air, and N at 502° resulted in 100% conversion of II, a I selectivity of 80.1%, HCHO selectivity of 2.1% and HOCH2CHO of trace amt.

quino - 16-2-2007 at 05:53

Title
Continuous preparation of glyoxal

Sauer, Wolfgang;
PATENT NO.
DE 2922599 The product gases (450-800°) from glyoxal prepn. (by oxidn. of glycol over Ag) were quenched (after at most 1 s after leaving the catalyst) with droplets (0-130°) of H2O or aq. glyoxal entering at an angle of 2-85° with the stream axis. Several examples were given in terms of numbered app. diagrams.

quino - 16-2-2007 at 05:56

Preparation of glyoxal by nitric acid oxidation of acetaldehyde

Chen, Zhangming;

Fujian Res. Inst. Struct. Matter, Acad. Sin., Fuzhou, Peop. Rep. China

Shiyou Huagong (1987), 16(8), 547-50

Glyoxal (I) was prepd. in 50% yield by HNO3 oxidn. of AcH at 40° and at HNO3/AcH mol ratio of 0.5-1.16. The effects of catalysts, NaNO3, and AcOH on the yield of I were detd. The reaction mechanism was briefly discussed.

quino - 16-2-2007 at 06:01

Preparation of glyoxal from ethylene glycol at gas phase

Wakimura, Kazuo;
PATENT NO.
JP 03232835 A
Glyoxal is prepd. by gas-phase oxidn. of ethylene glycol with mol. O in the presence of Ag supported on silicon carbide powders as a catalyst and P (derivs.). A gaseous mixt. contg. ethylene glycol, H2O, air, N, and tri-Et phosphite was passed through a reactor packed with silicon carbide-supported Ag at 585° to give glyoxal in 99.9% conversion and 84.3% selectivity, vs. 99.9% and 64.8%, without silicon carbide, resp.

quino - 16-2-2007 at 06:04

Preparation of glyoxals

Wakimura, Kazuo;
PATENT NO.
DE 19519426 A1 The title process comprises oxidative dehydrogenation of glycols in the presence of P or a P compd. and a catalyst comprising Ag and .gtoreq.1 of Au, Pt, Rh, and Pd. Thus, MeCH(OH)CH2OH, (MeO)3P, air, water, and N were passed through a reactor contg. a catalyst comprising Ag and Au at 491° to give 99.8% conversion with 69.7% selectivity for MeCOCHO.

franklyn - 15-4-2007 at 22:16

Quote:

Originally posted by The_Davster
For Acquisition, contact your favorite photography supplier and ask them to get it for you, it is slowly replacing formaldehyde as it is less toxic, some suppliers already have it in stock.

Not much use to me but for those who care I discovered this source _

http://www.photoformulary.com/DesktopModules/StoreProductDet...

But even for me, two hundred twenty thousand dollars a pint seems a bit steep .

Sauron - 16-4-2007 at 00:52

There was another item on that page Chemicals - G that ought to interest the members who read PIHKAL all the time.

Gallic Acid 100 g $80

Glyoxal from Ozonolysis of Benzene

franklyn - 6-11-2009 at 22:45

What I don't get is that this is exactly how the Ozonide is made
http://www.sciencemadness.org/talk/viewthread.php?tid=1172#p...
DMSO solvation then determines the product. Cool if it works.
- If anyone can obtain this article please post it in References -

http://pubs.acs.org/doi/abs/10.1021/i360029a017
Glyoxal from Ozonolysis of Benzene
William P. Keaveney, Raymond V. Rush, James J. Pappas
Industrial & Engineering Chemistry Product Research & Development
1969, 8 (1), pp 89–92

It would seem too that Ethandial is becoming an industrial staple.
http://www.entrepreneur.com/tradejournals/article/198473070....

.

Glyoxal by ozonolysis of benzene.gif - 52kB

jnik - 15-4-2012 at 20:54

Full article "Glyoxal from Ozonolysis of Benzene"

Attachment: Glyoxal from Ozonolysis of Benzene.pdf (509kB)
This file has been downloaded 2207 times

AndersHoveland - 15-4-2012 at 21:37

Glyoxal can be made by reacting acetaldehyde with selenium dioxide. yield is about 60%; the selenium can be recycled by oxidation with nitric acid or hydrogen peroxide. Acetic acid acts as an inhibitor against the undesirable rearrangement to glycolic acid. The temperature is ideally kept between 65–80 °C

Alternatively, dichloro-dioxane ( with four chlorine atoms [C2H2Cl2O]2 ), can hydrolyzed to glyoxal. Dichloro-dioxane is considered a "chloro-ether", and can be made by the reaction of acetyl chloride with ethyl acetate. Myolo (1911)

A less practical, but more interesting route is to use 2-Iodoxybenzoic acid, which can oxidize methanol to formaldehyde in 94% yield, and can similarly oxidize ethylene glycol (vehicle anti-freeze) to glyoxal. However, dimethyl sulfoxide (DMSO) can not be used as a solvent for the latter, as its pressence will cause the ethylene glycol to be oxidized to formaldehyde instead. The 2-Iodoxybenzoic acid can then be re-oxidized and recycled after completion of the reaction.

[Edited on 16-4-2012 by AndersHoveland]

CMOS - 5-9-2012 at 08:40

Hi
Does anyone know how to get glioxal from ethylene glycol solution? I think that precipitating glioxal with NaHSO3 would be the easiest way, but will it work in glycol solution?

CMOS - 15-8-2013 at 09:46

So, I've tried making glioxal by method described in polish patent PL126434B2 (by passing air/ air/oxygen /pure oxygen through ethylene glycol with catalyst, Me(RCOOH)xnH2O where Me=Cu,Co,Mn or other transitional metal, heated to 140-160*C for 20h. Yield: 7-10% molar conversion ). Catalysis supposed to stay unchanged, but mine (I used copper acetate) got reducted to metallic copper so, I filtered it out. I've made Benedict's test and it turned out positive. I want to use NaHSO3 to precipitate aldehyde, but how? Should I just add glioxal/glycol to solution of NaHSO3 ?

[Edited on 16-8-2013 by CMOS]

IPN - 16-8-2013 at 06:31

Yeah, just add your glyoxal-containing solution to an excess of ethanolic solution of sodium bisulfite and the adduct should precipitate out.
A 50/50 EtOH/H2O solution should be fine (usually 40% in NaHSO3), you can wash the precipitate free of water and organics with ethanol followed by ether.
The adduct can be broken with formaldehyde.

Glyoxal Synthesis

WGTR - 19-8-2014 at 13:50

Here is a reference that might be useful to someone who wants a simple lab prep for glyoxal. I haven't tried it yet, but intend to shortly. It uses sodium bisulfite and tartaric acid as starting materials, and looks pretty simple if it works.

The book is in German, and here is the link in Google Books:
http://books.google.com/books?id=AQ42AQAAMAAJ&dq=edition...

Here are the pages in German:

I have typed out and google-translated the article to the best of my ability, but would appreciate it if someone would like to clean it up. Here it is in English:

"O. Hinsberg: About the ketonic against some sodium bisulfite:

Dioxy wine soda is well known, when heated in aqueous solution in tartronsaures soda over by the glyoxal carbon soda, which probably formed initially by carbon dioxide elimination, is rearranged in the moments of occurrence under water absorption.

It is possible now easy to show with certainty that in the carbonic acid elimination from the first dioxy tartaric acid aldehyde arise when one carries out the cleavage in the presence of an agent which immediately binds with the aldehyde group. This agent is sodium bisulfite.

Plotting dioxy wine soda into a warmed to 80-100 ° concentrated solution of sodium bisulfite, a violent bubble formation takes place during which all dioxy wine soda dissolves. After completion of the reaction, crystallizes from the cooled liquid from Glyoxalnatriumbisulfit, which can easily identify it by its reactions with phenylhydrazine and o-toluene diamine. The Reactionsverlauf is therefore:

02.jpg - 5kB

It has not been successful, the first product of carbon dioxide elimination, namely to take the Glyoxalcarbonsäure; also if you keep the temperature of the bisulfite solution is so low that the development of carbon dioxide slowly of goes (ie, 60-70 °) after completion of the development only glyoxal available.

Since the dioxy tartaric acid is easily generated from nitro tartaric acid, it seemed possible that these also go on in Glyoxal on heating with acid sulphite salts. The experiment has shown that, in fact, a reaction in the indicated direction occurs, however, the yields of glyoxal are always low; were obtained about 20 per cent of the theoretical amount at best. The method is thus suitable for the production of glyoxal bisulfites.

The favorable course of the experiments just described, gave rise, some other ketonic acids, their esters, respectively, to check on their behavior towards sodium bisulphite.

The pyruvic acid, which has been studied for this purpose, showed against the reagent a resistance which at least that is equivalent to diluted mineral acids, for even as it was heated pyruvic acid with sodium bisulfite solution in the tube to 170 °, by far the greater part of the organic acid was unchanged. Products of decomposition of pyruvic acid could not be detected.

Chloro acetoacetate disappears on prolonged heating with a concentrated solution of sodium bisulfite on the water-bath. The decomposition of the ester appears to proceed in the usual way, ie according to the scheme of the acid cleavage, because you will get no trace of chlorine acetone, which is so easy erkeunbar yes by his awful smell when the supersaturated sodium bisulfite solution with dilute hydrochloric acid and then distilled in steam power.

Acetoacetic ester itself is not decomposed by prolonged heating with sodium bisulfite solution at 100 °.

From these experiments it appears that in the presence of sodium bisulfite, the tendency to separation of carbon dioxide from ketonic acids, esters thereof, respectively, is not substantially increased. In contrast, the bisulfite exercises where the spin-off without this already at a low temperature (100 ° and below) is going on, a protective influence on resulting aldehyde groups from."

Praxichys - 16-10-2014 at 06:58

Weinsäure is tartaric acid and Weinsäures Natrium is sodium tartarate. "Dioxyweinsäure" I think is dihydroxytartaric acid. See http://pubs.acs.org/doi/abs/10.1021/ja01442a013

Quote:

When sodium dihydroxytartarate is poured into a warmed 80-100° concentrated solution of sodium bisulfite, a violent bubble formation takes place during which all of the sodium dihydroxytartarate dissolves. After completion of the reaction, glyoxal sodium bisulfite crystallizes from the cooled liquid, which can easily be identified by its reactions with phenylhydrazine and o-toluene diamine.

...

It has not been successful to isolate the product of a single carbon dioxide elimination, namely to take the glyoxylic acid; even if you keep the temperature of the bisulfite solution is so low that the development of carbon dioxide slowly of goes (ie, 60-70 °) after completion of the generation of gas, only glyoxal is available.

Since the dihydroxytartaric acid is easily generated from nitrotartaric acid, it seemed possible that these could convert to Glyoxal on heating with acid sulphite salts. The experiment has shown that, in fact, a reaction in the indicated direction occurs, however, the yields of glyoxal are always low; were obtained about 20 per cent of the theoretical amount at best. The method is thus suitable for the production of glyoxal bisulfites.

Glyoxal sodium bisulfite addition compound hydrate from the Aldrich website.

Nitrotartaric acid, US 1506728 A:

Quote:

As an illustration 200 pounds of tartaric acid may be first dissolved in 100 pounds boiling water, and stirred until dissolved. The dissolved tartaric acid is then added to 1500 pounds of mixed acid, containing twenty five per cent nitric acid. The entire mixture is then agitated and the temperature is maintained at approximately 75 degrees centigrade. When the entire mixture has been thoroughly stirred, it is cooled and the nitrotartaric acid will settle or precipitate in the form of large crystals, which may be readily separated in an almost pure form.

Dihydroxytartaric acid

The nitrotartaric acid is very easily hydrolyzed.

Journal of the American Chemical Society, Volume 43, Issues 1-6. Free Google ebook. pp. 577

Quote:

When solutions of nitrotartaric acid are allowed to stand, they soon turn blue, gases are given off, and much heat is evolved. If the temperature is kept under control by water cooling, the process lasts from one to two days. The gases consist at first of nitrogen trioxide; later they become colorless, and are composed of nitric oxide and carbon dioxide. The solution contains chiefly dihydroxy-tartaric acid, which may be precipitated by addition of sodium acetate or carbonate as the very insoluble sodium dihydroxy tartarate; it also contains tartronic and oxalic acids. The yield of sodium dihydroxy-tartarate is from 75-80%.

In a nutshell:

1. Nitrate some tartaric acid.
2. Hydrolyze the nitrotartaric acid in water with cooling. Precipitate with sodium carbonate, filter.
3. Mix with a solution of sodium bisulfite at 80-100C.
4. Cool solution to precipitate glyoxal sodium bisulfite hydrate.

And now remains the task of isolating the glyoxal from the bisulfite addition compound. Apparently this can be done with formaldehyde but that is equally annoying to get.

[Edited on 16-10-2014 by Praxichys]

WGTR - 16-10-2014 at 09:31

Thank you very much for posting this. The information is indispensable, and makes up for my poor German translation skills. I was struggling through another translation of that when you posted.

I have been thinking of perfecting a glyoxal synthesis for a while, and have tried very small-scale reactions of various types. Some different pathways that I have tried/considered:

1. Nitric acid oxidation of ethanol/acetaldehyde (30-35°C) with copper catalyst.
2. Nitric acid oxidation of ethylene glycol at 25°C.
3. Sodium bismuthate oxidation of tartaric acid.
4. Selenium dioxide oxidation of acetaldehyde.
5. Dehydrogenation of ethylene glycol in the gas phase over copper.
6. Dehydrogenation of ethylene glycol in the liquid phase with copper oxide (≈180-190°C).
7. Reaction of Dihydroxytartaric acid with sodium bisulfite.
8. Ozonolysis of Acetylene.

I can certainly buy it (and I have, just to obtain a reference sample), but it would be an interesting chemical to make. Ultimately it will be used to make imidazolium-based ionic liquids. These can also be bought, but they are quite expensive. It would be kind of cool to do a total synthesis of an expensive ionic liquid.

I can make it using any of the above methods, but I'm trying to reduce the process down to something that doesn't use significant amounts of expensive or uncommon reagents. Yields need to be good, or else the desired product should be easy to separate from the side products (or the contaminants should not interfere with the following reactions) . Also, if custom equipment is needed, then it needs to be something that can be made or obtained by a wide variety of people. Ideally it should not be a process that is unnecessarily dangerous. Anyway, I have my work cut out for me. I have to run, if I have time later I'd like to add some references for the processes above. I have them buried in my stack of papers on the desk.

Praxichys - 16-10-2014 at 10:46

I too am searching for as reliable way to make glyoxal in the laboratory. I need it for some furazan derivatives I am working on, and for a simple compound it sure is expensive!

So far I have started by dehydrogenating ethanol to acetaldehyde (with awful yields) in a hot copper coil, and plan to go the HNO3 oxidation route, or perhaps try directly the gas phase oxidation of ethylene glycol. The yield is so bad for a single hydroxyl that I am doubtful if I can get anything useful at all with the glycol.

Bismuthate oxidation

I am very interested in your third reference with the bismuthate oxidation. I have done some quick online searching, and it looks like sodium bismuthate and tartaric acid in a 2:1 ratio in 3N sulfuric acid gave a 70% yield of glyoxal. I found that here. The sticking point with this one is the regeneration of the bismuthate which is no easy task.

I found a thread here where plante1999 states:

Quote:

I made a solution of 7g of KOH in 10ml of water. I added 2g of Bi2O3 and I heated the solution to boiling. When the solution was boiling I passed chlorine in, until chlorine started to escape from the solution. The yellow bismuth trioxide turned violet-brown during the oxidation. The solution was dumped in 200ml of cold water. The cold water was decanted, and the precipitate washed with 100ml of cold water.

Not too bad, really.

Cu, Co, Mn catalyzed air oxidation in liquid phase

There is also a reference to polish patent PL126434B2 written above in this thread that uses the air oxidation of liquid phase glycol at 140-160C with a catalyst of Cu, Co, or Mn acetate. Reaction time is ~20h and yields are low, (something like 7-10% allegedly) but all the reagents are all readily available and inexpensive. Theoretically the glyoxal might distill off of such a mixture during the reaction and could be collected continuously.

I think I am going to give this one a try. I know no Polish but I will run a Google translate on it.

Attachment: PL126434B2.pdf (336kB)
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[EDIT]

From the translation (cleaned up a bit):

Quote:

It was found that the most effective catalysts for the oxidation of ethylene glycol acid in the liquid phase with molecular oxygen, are complexes of transition metals, szcze¬ cially copper (II) and cobalt (II) of the formula: M (RCOO) xin H2O (where M = Cu, Co, Mn, V or other The transition metal R = H, alkyl). The oxidation may be carried out with pure oxygen, air or enriched air oxygen.

Quote:

Example IV. In [a reactor] as in Example II provided ethylene glycol which was dissolved 0.5 mol of Cu (CH3COO) 2H20. Oxidation air flow 2501 / hr. (I assume this is 250 liters per hour) carried out at 140 ° C for 20 hours. Conversion of ethylene glycol the glyoxal was 7.0 mol%.

EXAMPLE The oxidation reaction as in Example IV was carried out at a temperature of 160 ° C. The conversion to glyoxal was 9.2 mol%. P r of y k ³ d VI. The oxidation of ethylene glycol was carried out as in Example V używa¬ ing ethylene glycol as the solvent in a weight ratio of dimethyl sulfoxide to
ethylene glycol as a 4: 1. Obtained in this case, the conversion of ethylene glycol to glyoxal was 14.5 mol%.

It would appear that they have bubbled air at 250 L/hr into one liter of ethylene glycol at 160°C with 0.5mol copper II acetate dihydrate dissolved in, in a mixture 4:1 DMSO to glycol/acetate solution, for 20 hours, yielding a 14.5% conversion to glyoxal.

It also says that the glyoxal is easily separated by distillation, the catalyst does not need regeneration, and the glycol can be recycled for the next run.

The difference in BP suggests that the glyoxal might be removable continuously, as the paper makes mention of a reflux condenser. I think this is a winner.

[Edited on 16-10-2014 by Praxichys]

Attachment: translation.txt (7kB)
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WGTR - 16-10-2014 at 20:02

Yes, the reference that you uploaded is the one that I am thinking of. There is one thing that bothers me about it, though. They isolate glyoxal by extracting with ether, which they neutralize with aqueous sodium carbonate. This might work if small amounts of carbonate are used, but if the product was completely neutralized, I think it would have resulted in sodium glycolate instead of glyoxal. Glyoxal is sensitive to pH, and rearranges to glycolate in basic conditions. In every other method I've seen, calcium carbonate is used instead, as it doesn't react with glyoxal. Maybe they were just careful, but it's always possible that they didn't actually do the experiment. I got distracted making sodium bismuthate, so I haven't tried to duplicate it yet.

For some simple sodium bismuthate experiments, I neutralized basic bismuth nitrate with sodium hydroxide. An excess amount of 30% hydrogen peroxide was added, and then sodium hydroxide pellets were added gradually with heavy stirring until the color started darkening, and gas began escaping. Over the next half hour or so the color began yellowing, and then a brownish color. The color varied from batch to batch. Some more peroxide was added just to be sure that the reaction would go no further. I can't say that this is sodium bismuthate; no reference that I saw mentions making it this way. When I acidified it with sulfuric acid, though, it would turn reddish, and this substance would be decolorized by room temperature ethanol. I didn't go much further with this method than this. The process of making it either this way, or the common way, is too costly considering the desired end product (glyoxal).

Are you dehydrogenating ethanol first to save on nitric acid? Nitric acid can act on ethanol directly. Anyway I used the method outlined in "US3429929 A", but only on mL quantities of ethanol, not acetaldehyde. I haven't scaled it up yet, or tested the products. I was more interested initially in how exothermic the reaction was, how hard it was to initiate (with nitrite), and some of the logistical issues in conducting the reaction. I'm not sure that I'll go this route, though, because a stoichiometric amount of nitric acid is needed for each quantity of glyoxal. Nitric acid is going to be hard to get for people in Europe, and it's a little expensive anyways.

Direct dehydrogenation of ethanol can be done. Sabatier did it, and I've had some success with it myself. The main thing is that time and effort need to be spent getting the reactor set up correctly. The catalyst beads were easy. They were made from copper and magnesium hydroxide. I strung them up like a necklace, and when dry, shoved everything down the reactor tube. It was essentially a "single-bead-string reactor". Heating of the reactor was not a problem. It took some firebricks and a short roll of Kanthal wire. I have pictures of this experiment, but I'll have to post them later if I have time. The main issues that I haven't resolved yet are the alcohol vaporization and metering. Once the alcohol vapors form, I don't want any condensation anywhere in the system until after the reactor. This avoids alcohol droplets getting pushed directly into the hot reaction tube (think: explosive catalyst bed deconstruction!) Without metering the alcohol, the experiment is not very informative. I need to think up a way to meter the alcohol into a device that will vaporize it instantly and smoothly, without allowing it to superheat and explode randomly. Anyway, it sounds like part of your problem is the fineness of the catalyst. Copper wire will not work well for ethanol dehydrogenation. It may work for methanol, though. For ethanol, catalyst beads made from fine powder are needed.

One thing to keep in mind about glyoxal, is that it is weird. If formed in a vapor phase reaction, it will be happy to remain in the vapor phase unless it is allowed to condense in the presence of water. Once it contacts liquid water, it polymerizes instantly, becoming essentially non-volatile up to its decomposition point. It can be dehydrated and distilled again, but only from something strong, like P2O5. This is mainly why it is sold in aqueous solutions.

I wish that I could expand on all of this right now, but I'm a little short on time right at the moment. Hopefully things will slow down a bit later.

[Edited on 10-17-2014 by WGTR]

Praxichys - 17-10-2014 at 06:40

That is a lot of helpful information about the dehydrogenator. I am interested in how you have prepared your catalyst beads.

Yes, the dehydrogenation was to save nitric acid, which I make myself. I am also not a big fan of the potential to generate ethyl nitrate, and the manufacture of good nitric acid is labor-intensive.

My reactor has no discreet catalyst and is simply a coil of bare copper tubing held in a hot flame. I chose the dehydrogenation route over oxidation because of the potential for an explosion, and the difficulties encountered while trying to regulate the ratio of alcohol vapor and air. The reactor did work to some extent but I found it in need of a pre-chiller because the absorption solution would get quite warm and reek of the aldehyde. I could tell it was working by the presence of small amounts of gas that would not be absorbed at the absorbtion stage - presumably the hydrogen. A redesign is in progress, since the apparatus would mean an unlimited supply of very cheap formaldehyde and acetaldehyde.

I suppose I should have mentioned that aq. glyoxal is sufficient for my purposes - no need for anhydrous/monohydrate, etc.

It does appear in the Polish patent that

- The mixture of glycol and glyoxal is separated from the catalyst by distillation (possibly under reduced pressure)
- The resulting mixture of glycol/glyoxal is used directly for organic synthesis

I wonder how readily the polymerized hydrates reconvert to aqueous glyoxal? This could be a useful isolation step. I think the hydrates compare to trioxane or paraldehyde. Perhaps acidifying the glycol/glyoxal solution with an aqueous acid will force much of the polymerized stuff back to free glyoxal which could be distilled. Furthermore, the BP of the mixture of DMSO and ethanediol is probably >190C - maybe sufficient to depolymerize any hydrates in the first place? Maybe a splash of sulfuric acid would allow glyoxal to distill out. I intend to absorb the vapor into deionized water.

Either that, or maybe warm the finished glyoxal/glycol with just enough water to form the dimer and trimer hydrates, then crash into water and filter them out.

I will have to run a big batch and split the resulting solution to see if I can get anywhere with this.

There are some interesting methods for interconverting glyoxal polymer hydrates to glyoxal in US2463030, specifically using 1,4-dioxane as a solvent and azeotropic water removal with toluene.

glyoxal synthesis

morsagh - 23-4-2016 at 10:50

Hi there, i am going to synthetise glycouril by reaction of urea, glyoxal, catalysed by P4O10 in aqeous solution (ref.: http://www.tandfonline.com/doi/full/10.1080/17518253.2012.71...) , and then polymerize to (6)cucurbituril with formaldehyde in conc. H2SO4. The only problem is i do not have any glyoxal so i want to prepare it by reaction of ethanol with nitric acid (maybe copper catalyst)... but i can´t find any reference to this method, does it really work, what are the yelds?

Boffis - 23-4-2016 at 12:49

Have you looked the couple of existing threads on glyoxal synthesis? Please use the search engine, you might find your answer.

morsagh - 23-4-2016 at 13:05

I found that thread but nothing usable. I would like to try HNO3 ethanol method but there aren´t written yelds etc..

WGTR - 23-4-2016 at 13:07

This has been a frustration of mine recently (in a fun sort of way). Making glyoxal isn't too difficult, I think. It's the workup and characterization that's difficult. Glyoxal polymerizes in traces of water, and isn't volatile up to its decomposition point unless first being dehydrated with phosphorus pentoxide. As long as glyoxal is kept in the gas phase, without being allowed to re-condense, it doesn't re-polymerize (I'll have to look for the patent that contains that information, I haven't tried that personally). It's slightly sensitive to "long" boiling in aqueous solution, so evaporation during work-up is usually done under reduced pressure, slightly above room temperature. Alcohol oxidation with nitric acid produces a mix of products, including glyoxal, glycolic acid, glyoxylic acid, oxalic acid, and acetic acid. Out of those, both glyoxal and glyoxylic acid are aldehydes, and give positive reactions to Tollen's reagent.

To answer your question about references, you can check on Google Books for "Experimental Chemistry for Junior Students, part 4", by J. Emerson Reynolds, published in 1887, pages 156-159. It explains the experimental procedure, as well as how to separate the products from one another.

Keep in mind that air conditioning didn't exist when the book was published, so the temperature of the room was merely recorded for reference. It might be possible to do the reaction faster, so long as the temperature can be kept low. A microchannel reactor design might be beneficial in this case. Also, the suggested calcium carbonate won't cause a Cannizzaro reaction with glyoxal, although calcium hydroxide will. Don't neutralize the reaction mix with something like sodium carbonate, because all of your glyoxal will end up as glycolate. Use ethanol to separate out the calcium salts, don't substitute with methanol or acetone. I tried acetone, and ended up with some strange, unidentified goop. The Tollen's test on that resulting mess was negative.

Getting rid of the residual nitric acid is a challenge, as it seems to stop reacting below a certain concentration. Evaporation merely concentrates it up to its constant boiling point, around 68% concentration. It's common to see what looks like a finished reaction, upon evaporation at warm temperatures to begin erupting suddenly in a furious boiling of orange fumes. That's one thing that I verified. Copper salts have been tried as a catalyst to reduce the nitric acid content to zero, but my volcanic eruptions have still happened while using copper salts in the reaction mixture. I don't know what to say about that, other than the catalytic method isn't apparently straightforward. It would seem logical to neutralize the excess nitric acid with calcium carbonate, but calcium nitrate is very soluble in all the generic alcohols and in acetone, so it will carry over with the glyoxal.

One idea to remove excess nitric acid, would be to first neutralize the reaction with calcium carbonate. After extraction with alcohol and then evaporation of the alcohol, proceed to an electro-dialysis stage in water. If calcium nitrate ionizes in alcohol (or with minimal water), then you can probably do this purification in pure or concentrated ethanol. The concept is simple. The anode and cathode compartments are packed with activated carbon, or some other electrically conductive carbon with high surface area (high surface area is important). The electrodes could be graphite. You're basically making an electric double-layer capacitor (a supercapacitor). This is intentionally a non-faradaic reaction. You don't want charges crossing the electrode/electrolyte interface, so the cell potential needs to be kept low, below about 0.5 volts. The positive and negative ions will adsorb on the surface of their respective electrodes, but I "DON"T THINK" the glyoxal should have any particular charge, so it can be flushed from the various compartments as soon as the cell current drops off close to zero.

[Edited on 4-23-2016 by WGTR]

morsagh - 23-4-2016 at 13:53

So what about separation by bisulfite after neutralization by CaCO3?

WGTR - 23-4-2016 at 14:46

It would have to be barium bisulfite instead of the sodium salt, if you intend to break the adduct later and precipitate the leftover salts. Obviously, you can't just simply distil off the glyoxal like you can with formaldehyde or acetaldehyde. Dilute sulfuric acid can be used to break the adduct and precipitate the barium, but it has to be done carefully. Excess acid will be painful to remove. Historically, lead acetate was used to remove traces of sulfate, and then, I think, dilute hydrogen sulfide was used to remove traces of lead.

Glyoxylic acid can also form a bisulfite adduct, so make sure that the reaction is neutralized fully before extracting with ethanol.

Dr. H. Debus wrote an article using some of these methods, and he was an early researcher, if not the discoverer of glyoxal. You can find it on Google Books, as The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Vol. XIII, 4th series, published 1857. pages 39-49.

morsagh - 24-4-2016 at 09:53

I think that in synthesis of curcubituril sodium salts won´t interfere... Or yes?

Quaff - 1-11-2017 at 08:22

heat sucrose in conc. h3po4 to 100c using oil bath for control. Employ a sweep gas, N2 or CO2, and what distills off is predominantly a mixture of glyoxal and methylglyoxal. these are good reducing agents in precious metal recovery

Glyoxal extraction from an OTC product

BAV Chem - 1-11-2023 at 05:00

Some time ago I came across an OTC product that apparently contains glyoxal. It's some sort of cleaning solution for camping toilets i think. I'm not into camping so I don't know what exactly it's used for. I'm gonna try to insert an image of said product here.

According to the MSDS this stuff has 0,1-1% of glyoxal in it. Judging by some experiments I've done it's somewhere in between. Assuming 0,5% of this solution is glyoxal there would be 12,5g of glyoxal in the 2,5l which I got for 9€. Not quite the best deal on glyoxal but I'm trying to extract it nonetheless so here's the best of my results so far:

I started with 500ml of solution which i boiled down to a slightly thick liquid. The starting material is mostly water with some blue dye, limonene, detergent and other stuff in it. After boiling it down I added a solution of sodium metabisulfite made by dissolving 5g of the latter in a mix of 33ml H2O and 22ml EtOH. This was then stirred for 3h and a white precipitate of the bisulfite adduct of glyoxal formed. I filtered it off the next day and washed it with ethanol.
Now to turn it back into glyoxal it was suspended in water, 10ml of 20% HCl were added and the mixture was heated on a water bath with the beaker covered with plastic wrap to avoid evaporation (basically a reflux for lazy people). HCl slowly decomposes the bisulfite adduct releasing SO2. After 2 or 3h of heating I removed the plastic foil and let it evaporate down. I added some water back in after a while to hopefully remove excess HCl.
When most of the liquid was gone the solution started to give off white fumes which was probably just excess HCl but i was afraid of my glyoxal evaporating so I took it off heat and shot in a generous amount of EtOH. This made a bunch more salt precipitate out. Then some sodium bicarbonate was added to the mix in order to neutralize leftover HCl. Undissolved salts were filtered off and washed with more ethanol. The solution was once again evaporated on a water bath until all the ethanol was gone. A few ml of liquid remained which should be mostly glyoxal.

It's flammable and partially burns up with a blue flame. Some water is left behind which leaves a white solid upon drying. This solid is probably some sort of hydrated glyoxal oligomer as it mostly decomposes and disappears into smoke when heated. I suspect the material I ended up with is just very wet glyoxal. It faintly smells like formaldehyde which is apparently what glyoxal smells like.

[Edited on 1-11-2023 by BAV Chem]

Fery - 1-11-2023 at 08:39

Well done BAV Chem! For some reactions you can use directly the adduct of glyoxal with bisulfite like o-phenylenediamine -> quinoxaline https://orgsyn.org/demo.aspx?prep=CV4P0824
I see your source is a German product. I ordered some glyoxal from Germany from https://shop.es-drei.de/aldehyde/12132/glyoxal-loesung-40-in...

the ethanolysis of CuBr2 gave a 65% yield of 1,1-dibromo-2,2-diethoxyethane

clearly_not_atara - 7-10-2024 at 11:57

Title.

49 hour reflux, slooooow conversion (72%), yield 90% (!!) as a percentage of converted CuBr2 (measured as wt. of CuBr ppt).

Quote:

A solution of 44.7 g (0.2 mol) of cupric bromide in 250 mL of absolute ethanol refluxed for 49 hours yielded 20.64 g (72.4%) of cuprous bromide and 5.9 g (90% of isoelectronic conversion) of 1,1-dibromo-2,2-diethoxyethane having bp 71-74 C (2.5 mm Hg) n²⁵D 1.4808 (lit nD 1.4802). A small amount of lower-boiling material was not investigated. The dibromo acetal emerged as one peak when gas chromatographed

Obtaining such a complicated thing in such a good yield from such ordinary stuff is the sort of thing I would expect that everyone knows about, but I had never heard of this reaction until today. Most surprisingly, the paper was uploaded here by solo some 20 years ago, but nobody seemed to notice or care about the relatively high yield and clean reaction for this product -- they wanted to make chloroacetone:
https://www.sciencemadness.org/whisper/viewthread.php?tid=71...
(file: Cupric Halide Halogenations Castro Paper)

Interestingly, the product is a substrate for the Takai olefination giving cinnamaldehyde acetals (though dibromo compounds react very slowly, on the order of weeks, so it may be Finkelsteined):
https://en.wikipedia.org/wiki/Takai_olefination

And of course, it is also probably a precursor to both glyoxal and glyoxal diethyl monoacetal, the latter being easier to use selectively in some cases. For hydrolysis of the dibromide, OrgSyn suggests a reflux with potassium oxalate:
http://orgsyn.org/demo.aspx?prep=CV4P0807
(I suspect the rxn time is so long on OrgSyn due to poor phase mixing, which may or may not be improved in our case.)

Fluorite - 8-10-2024 at 00:06

there are some descriptions that mention its vapor having a greenish color. I’m really curious about this and was wondering if anyone here has ever managed to capture an image of glyoxal vapor? If you do, I would love to see it!

Boffis - 10-10-2024 at 12:55

C_n_atara: I presume that the cupric bromide must be the anhydrous sort? But yes this is a really interesting reaction and certainly worth a try.

Has anyone ever tried to prepare anhydrous copper II bromide?

clearly_not_atara - 10-10-2024 at 14:40

Boffis: I'm pretty sure that's a "yes". Wikipedia states:

Quote:

If heated above 18 °C, it [CuBr2] releases water to produce the anhydrous form.

But it also says that the product is dried under vacuum or with phosphorus pentoxide, which is a little more harsh.

Precipitates - 10-10-2024 at 19:21

The products in this thread look pretty anhydrous:

Copper bromide from copper sulphate

Quote: Originally posted by clearly_not_atara

But it also says that the product is dried under vacuum or with phosphorus pentoxide, which is a little more harsh.

I guess for a super dry product