Glycolic acid oxidation

EG may also be pioduced via glycolic acid using catalysts containing strong acids (66), cobalt carbonyl (67—69), rhodium oxide (68), or HE solvent (70,71) (see Glycols, ETHYLENE glycol). 

Other possible chemical synthesis routes for lactic acid include base-cataly2ed degradation of sugars oxidation of propylene glycol reaction of acetaldehyde, carbon monoxide, and water at elevated temperatures and pressures hydrolysis of chloropropionic acid (prepared by chlorination of propionic acid) nitric acid oxidation of propylene etc. None of these routes has led to a technically and economically viable process (6). 

Nitric acid oxidation is used where carbohydrates, ethylene glycol, and propylene are the starting materials. The diaLkyl oxalate process is the newest, where diaLkyl oxalate is synthesized from carbon monoxide and alcohol, then hydrolyzed to oxahc acid. This process has been developed by UBE Industries in Japan as a CO coupling technology in the course of exploring C-1 chemistry. 

Ethylene Glycol Process. Oxahc acid is also prepared by the nitric acid oxidation of ethylene glycol (15—21), and the process is basically the same as in the case of carbohydrates except for the absence of the hydrolyzer (see Eig. 1). In this process, ethylene glycol is oxidized in a mixture of... 

In the chemical industry, titanium is used in heat-exchanger tubing for salt production, in the production of ethylene glycol, ethylene oxide, propylene oxide, and terephthaHc acid, and in industrial wastewater treatment. Titanium is used in environments of aqueous chloride salts, eg, ZnCl2, NH4CI, CaCl2, and MgCl2 chlorine gas chlorinated hydrocarbons and nitric acid. 

Lclobanincs, CuHjjOaN (Formula XVIII). These are diketo-bases resulting from the chromic acid oxidation of the corresponding lelobanidines. Those recorded in Table B are Z- and dZ-forms, derived from ZI and ZII, and dl forms of lelobanidine respectively, dZ-lelobanine is the best known of these products. The methiodide, not isolated, on treatment with silver oxide yields dimethylamine and a neutral, deep-yellow oil convertible by hydrogenation into a glycol, b.p. 117-8°/0-03 mm.,... 

Kataoka M, Sasaki M, Hidalgo AR, Nakano M, Shimizu S (2001) Glycolic acid production using ethylene glycol-oxidizing microorganism. Biosci Bio-technol Biochem 65(10) 2265-2270... 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

C-C fission to give IV for both V(V) and Mn(III). Kemp and Waters have established two main features of these oxidations, namely, (i) for the oxidations of QH5CD(0H)C02H and the light compound are V(V), 2.0 Mn(III) sulphate, 1.2 Ce(lV) sulphate, 1.1 and (i7), that the trend of rates of oxidation of mandelic, a-hydroxyisobutyric, lactic and glycollic acids is as expected for Ce(IV) and Mn(III) if stabilisation of the radical RCHOH is important, but is altered for V(V) (Fig. 4). It appears from the latter observations that the presence of a-hydrogen atoms causes a drop in rate by a factor of almost 10 per a-hydrogen... 

Oxidative decarboxylation, after the manner of RCO2H (vide supra), is ruled out because the product, glycollic acid, is only slowly oxidised by Mn(III) pyrophosphate yet all equivalents of Mn(III) are consumed rapidly . ... 

The oxidation of tartaric and glycollic acid by chromic acid also induces the oxidation of manganous ions. In the presence of higher concentrations of manganese(II) the rate of oxidation of the acids is diminished to about one-third of that in the absence of manganous ions. The decrease of the rate has been attributed to manganese(II) catalysis of the disproportionation of the intermediate valence states of chromium probably chromium(IV). 

DuPont has developed a process for the manufacture of glyoxylic acid by aerobic oxidation of glycolic acid (Fig. 2.33) mediated by whole cells of a recombinant methylotrophic yeast (Gavagnan et al, 1995). The glycolic acid raw material is readily available from the acid-catalysed carbonylation of formaldehyde. Traditionally, glyoxylic acid was produced by nitric acid oxidation of acetaldehyde or glyoxal, processes with high E factors, and more recently by ozonolysis of maleic anhydride. 

S (2)-hydroxy-3-butenenitrile from acrolein and HCN trans hydrocyanation using, for instance, acetone cyanohydrin Hydrolysis of nitriles to amides, e.g. acrylonitrile to acrylamide Isomerization of glucose to fructose Esterifications and transesterifications Interesterify positions 1 and 3 of natural glycerides Oxidation of glucose to gluconic acid, glycolic acid to glyoxalic acid... 

Alcohols may be corrosive to some aluminum alloys. In an aqueous mixture corrosion may still occur because of dissolved ions from residual salts. At high temperatures and in the presence of residual oxygen from the air, glycols are oxidized slowly to the corresponding acids. These acids can corrode metals. 

Figure 14-4. Oxidation of ethyiene giycol to glycolic acid and oxaiic acid.

Figure 34. Cell size in porous oxides versus anode potential for different electrolytes A, oxalic acid , phosphoric acid O, glycolic acid 3, tartaric acid.224...

Acetic acid appears to function both as an accelerator for the oxidation and an inhibitor of the rearrangement to glycolic acid. 

The oxidation of a-hydroxy acids is slow41 it has been comprehensively studied, using glycolic acid as a model.42 Three reactions have been proposed as occurring. 

Some of the earliest work in the oxidation of alkenes was performed by oxidation with potassium permanganate. Under acidic and neutral conditions the intermediately formed glycols are oxidized, generally leading to cleavage of the carbon-carbon bond. Thus, such procedures have seldom been synthetically applied to diene oxidation. One notable... 

A mixture of Pt(ll) and metallic Pt in an aqueous medium was shown to oxidize ethane to yield acetic and glycolic acids. A series of deuterium-exchange processes enabled a complex mechanism to be elucidated metallic platinum catalyzes the oxidation of intermediate alcohols to acid products, whereas the Pt(ll) salt activates the initial alkene (Scheme 7X29... 

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