Glyoxal solution

Figure 12.9 Salivary gland fixed in a glyoxal solution (Prefer, Anatech Ltd.). Membranes around mucus cells are unusually clear and nuclear chromatin is sharply defined. 

In the absence of sodium bisulfite, aqueous glyoxal solutions react with o-phenylenediamine to give only about 30% yields of quinoxaline together with large quantities of resinous by-products. Therefore, if an aqueous glyoxal solution is to be used in this preparation it should be mixed with a water solution of. two molar equivalents of sodium bisulfite before it is added to the o-phenylenediamine solution. 

Aldehydes Acetaldehyde Acrolein (inhibited) Butyraldehyde Dec aldehyde Ethylhexald ehyde Formaldehyde Glutaraldehyde Solution Glyoxal Solution Methylbutyraldehyde Octyl Aldehyde Pentyl Aldehyde Propionaldehyde Valeraldehyde... 

Dimethyl 1,3-acetonedicarboxylate, aqueous 40 glyoxal, and biacetyl were purchased from Aldrich Chemical Company, Inc. The submitters advise against using glyoxal solution that contains a significant amount of white solid. 

There are several examples of this approach to thiophenes. The reaction of thiophenol with acetylene in the vapor phase at 600-650 °C gave benzo[h]thiophene in 71% yield. p-Toluenethiol affords 5-methylbenzo[h ]thiophene in 54% yield under the same conditions (54HC(7)l). The best example of this type of synthesis was the reaction of 3-mercaptocy-clohexanones (235) with glyoxal to form the thiophenes (236), which was the subject of a patent (70USP3511854). The reaction proceeds smoothly under reflux conditions, using ah inert solvent, such as benzene or toluene, which will azeotrope with water, and a protic acid catalyst. A solution of (235) in the solvent is added to 40% aqueous glyoxal solution containing some acid. After reflux the thiophene (236) can be isolated in 70-90% yield. 

Quinones. Sager developed a procedure for the preparation of tetrahydroxy-1,4-henzoquinone in which 30% glyoxal solution is added to a bicarbonate-buffered solution of sodium sulfite and a brisk stream of air is drawn through the solution. 

Glyoxal (OHC-CHO) is a dialdehyde that can be obtained from several natural sources, such as from the oxidation of lipids or as a by-product of biological processes (Hirayama et al., 1984). The low vapor tension of the glyoxal solution and its low toxicity are some of the advantages of using... 

To 100 gm of 32% (0.55 mole) glyoxal solution at pH 7.0 (sodium carbonate) is added 50 gm (0.83 mole) of urea. The temperature rises to 35°-40°C in the course of about hr, and the solution is then stirred for 12 hr while being cooled to about 0°C. Approximately 25 gm of the product precipitates, and evaporation to half volume at 35°C under reduced pressure affords another 15 gm of product. The total yield is 61%, m.p. 140 -142 C. 

Reagents Borate buffer—Boric acid, 2-76 g, N sodium hydroxide, 23 -4 ml, water to 100 ml. Glyoxal solution (freshly prepared)— A 0-22 per cent solution of glyoxal sodium bisulphite in water. Gelatin solution (freshly prepared)—To 100 ml of hot water add 1 g of gelatin B.P.y previously broken into small pieces, shake until dissolved and cool. 

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