Glycerol oxidation products

Figure 3. Product composition vs. time Figure 4. Product composition vs. time for glycerol oxidation under basic for glycerol oxidation under acidic conditions on 5%Pd/C. conditions on 7%Pt3%Bi/C.

Au/C was established to be a good candidate for selective oxidation carried out in liquid phase showing a higher resistance to poisoning with respect to classical Pd-or Pt-based catalysts [40]. The reaction pathway for glycerol oxidation (Scheme 1) is complicated as consecutive or parallel reactions could take place. Moreover, in the presence of a base interconversion between different products through keto-enolic equilibria could be possible. 

In view of the use of glycerol as a chemical commodity for the production of chemical intermediates, an overview will be made of existing catalytic knowledge. More specifically, glycerol oxidation, dehydration, hydrogenolysis, oligomerization/polymerization, polyol formation, and formation of a few miscellaneous products will be dealt with. 

The Pt/C catalyst, compared with Pd/C, showed not only enhanced activity (vide supra) but also reduced selectivity for glyceric acid (only 55% at 90% conversion), favoring dihydroxyacetone formation up to 12%, compared with 8% for the Pd case [48]. The Pt/C catalyst promoted with Bi showed superior yields of dihydroxyacetone (up to 33%), at lower pHs. Glyceric and hydroxypyruvic acids, apparently, are formed as by-product and secondary product, respectively [48], The addition of Bi seems to switch the susceptibility of glycerol oxidation from the primary towards the secondary carbon atoms. 

Structurally, these acids are cunsidered to be the oxidation products of polyhydric alcohols. However, a number of them can be formed from the oxidation of sugars. The careful oxidation of glycerol will yield a syrupy liquid, glyceric acid, an example of a dihydroxymonobasic carboxylic acid. 

Alvarez-Gonzalez et al. [74] Glycerol Plant-extract syrup Glycerol dehyrogenase (NAD+)/by electropolymerised layer of nonconducting poly-(o-phenylenediamine) (PPD) Carbon paste electrodes modified with the oxidation products of NAD+/0mV vs. Ag/AgCl ... 

Fischer subsequently obtained a-acrose alone, by tho polymerising influence of one per cent, sodinm hydroxide upon glycerose, an oxidation product of glycerol.18... 

Demirel S, Lehnert K, Lucas M, Claus P. Use of renewables for the production of chemicals glycerol oxidation over carbon supported gold catalysts. Appl Catal B Environ. 2007 70 637-43. 

Oxidation Products of Poly-hydroxy Alcohols.—In our study of the mixed poly-substitution products we considered the mixed alcohol-aldehyde and alcohol-ketone compounds and showed that they are intermediate oxidation products between poly-hydroxy alcohols and poly-basic acids (p. 228). To illustrate, when glycerol, tri-hydroxy propane, is oxidized the following products are obtained. 

VI, V2), for removal of phospholipids. The extracts are then introduced into the automated analsrtical system for carrying out saponification of triglycerides to glycerol, oxidation to formaldehyde, followed by condensation with diacetylacetone and ammonia to give a fluorescent product, 3,5-diacetyl-1,4-dihydrolutidine. 

Glycerol, a product of fat metabolism in adipose tissue, is transported to the liver in the blood, and then converted to glycerol-3-phosphate by glycerol kinase. (Glycerol kinase is found only in liver.) Oxidation of glycerol-3-phosphate to form DHAP occurs when cytoplasm NAD+ concentration is relatively high. 

A large number of products can be obtained from glycerol oxidation processes (Scheme 3.7). If the secondary hydroxy group of glycerol is oxidized selectively, dihydroxyacetone (DHA) is formed. DHA has been used for years as an active... 

Dihydroxyacetone (DHA), the oxidation product of the secondary hydroxy group of glycerol, is an artificial tanning agent in cosmetics and a pharmaceutical intermediate. Glycerol oxidation in acidic medium on a platinum-bismuth catalyst (Bi/ Pt atomic ratio = 3) prepared by coprecipitation of Pt and Bi salts, yielded 20 % DHA at 30 % conversion [70]. The deposition of bismuth on platinum particles by oxido-reduction (Bi/Pt = 0.13) yielded 37 % DHA at 70% conversion... 

After removal of other oxidizable material, the glycerol content of tobacco could be estimated by oxidation of the glycerol and conversion of its oxidation product to its 2,4-DNPH derivative. 

Allyl alcohol is isomeric with propylic aldehyde and with acetone. Being an unsaturated compound, it is capable of forming products of addition with Cl, Br and 1, etc., which are isomeric or identical with products of substitution obtained by the action of the same elements upon glycerol. Oxidizing agents convert it first into acrolein, acrylic aldehyde, CsH40, and finally into acrylic acid. It does not combine readily with H, but in the presence of nascent H combination takes place slowly, with formation of propylic alcohol. 

Previous studies about the glycerol oxidation in heterogeneous liquid phase [34-39] as well as in electrochemical environment [13, 40-42] show that glycerol react on metal surfaces through a complex mechanism that lead to the formation of a large variety of final reaction products, including compounds with one, two and three carbon atoms. There are evidences that the pH [13, 40, 41, 43], the nature of... 

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