Lactic acid hydrolysis

Mohd-Adnan, A.-F., Nishida, H., and Shirai, Y. (2008). Evaluation of kinetics parameters for poly(L-lactic acid) hydrolysis under high-pressure steam, Polym. Degrad. Stab., 93,1053-1058. 

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). 

Biacetyl is produced by the dehydrogenation of 2,3-butanediol with a copper catalyst (290,291). Prior to the availabiUty of 2,3-butanediol, biacetyl was prepared by the nitrosation of methyl ethyl ketone and the hydrolysis of the resultant oxime. Other commercial routes include passing vinylacetylene into a solution of mercuric sulfate in sulfuric acid and decomposing the insoluble product with dilute hydrochloric acid (292), by the reaction of acetal with formaldehyde (293), by the acid-cataly2ed condensation of 1-hydroxyacetone with formaldehyde (294), and by fermentation of lactic acid bacterium (295—297). Acetoin [513-86-0] (3-hydroxy-2-butanone) is also coproduced in lactic acid fermentation. 

Polylactic Acid. Polylactic acid (PLA) was introduced in 1966 for degradable surgical implants. Hydrolysis yields lactic acid, a normal intermediate of carbohydrate metaboHsm (23). PolyglycoHc acid sutures have a predictable degradation rate which coincides with the healing sequence of natural tissues. 

Trichodesmine, CigHa70gN, m.p. 160-1° (dec.), [ ]d+ 38° (EtOH), gives a methiodide, m.p. 202° (dec.), and on alkaline hydrolysis yields retronecine (p. 607) and dZ-lactic acid with isobutyl methyl ketone, the latter probably arising from a -ketonic acid first formed. ... 

Many acids other than sulfuric acid have been used for the challenging cyclodehydration step. It is important to note that when the concentration of sulfuric acid is below 70%, hydrolysis of the imine or enamine occurs. As previously mentioned, HCl/AcOH, ZnCla, PPA, POCI3, and lactic acid have been successfully applied to promote the cyclization. Chloroacetic acid was found to perform similar to lactic acid. Concentrated HCl, p-TsOH, and have proven beneficial in generating linear... 

Several carbohydrates such as corn and potato starch, molasses and whey can be used to produce lactic acid. Starch must fust be hydrolysed to glucose by enzymatic hydrolysis then fermentation is performed in the second stage. The choice of carbohydrate material depends upon its availability, and pretreatment is required before fermentation. We shall describe the bioprocess for the production of lactic acid from whey. 

The rate of hydrolysis of the partially ethoxylated polymer was retarded, although not to the extent calculated from theory (Fig. 25), suggesting some contribution to the rate of chain scission by an uncatalyzed process. End-capping poly (glycolic acid-co-lactic acid) has a similar effect on the rate of hydrolysis of this polyester (100). 

The effects of a series of added tertiary amines on the rate of chedn scission of other polyesters, including poly( e-caprolactone-co-lactic acid), has been studied and found to be equally great (65). The mechanism with tertiary amines can only be general base catalysis for the effectiveness of the amines was not related to their pK values or lipophilicities. The acceleration of the hydrolysis of the polyesters was used as a strategy for controlling the drug release rate. 

Pyruvic acid is the simplest homologue of the a-keto acid, whose established procedures for synthesis are the dehydrative decarboxylation of tartaric acid and the hydrolysis of acetyl cyanide. On the other hand, vapor-phase contact oxidation of alkyl lactates to corresponding alkyl pyruvates using V2C - and MoOa-baseds mixed oxide catalysts has also been known [1-4]. Recently we found that pyruvic acid is obtained directly from a vapor-phase oxidative-dehydrogenation of lactic acid over iron phosphate catalysts with a P/Fe atomic ratio of 1.2 at a temperature around 230°C [5]. 

In addition to solvent uses, esters of lactic acid can be used to recover pure lactic acid via hydrolysis, which in-tum is used to make optically active dilactide and subsequently polylactic acid used for drag delivery system.5 This method of recovery for certain lactic acid applications is critical in synthesis of medicinal grade polymer because only optically active polymers with low Tg are useful for drug delivery systems. Lactic acid esters themselves can also be directly converted into polymers, (Figure 1), although the commercial route proceeds via ring-opening polymerization of dilactide. 

The excess acidity method has been used to show that some reactions do have pure A2 mechanisms, for instance the hydrolysis of some benzohydroxamic acids,126,211 the hydrolysis of sultams,212 and the oxidation of lactic acid in... 

Linamurin is the principal cyanogenic glycoside in cassava its toxicity is due to hydrolysis by intestinal microflora releasing free cyanide (Padmaja and Panikkar 1989). Rabbits (Oryctolagus cuniculus) fed 1.43 mg linamurin/kg BW daily (10 mg/kg BW weekly) for 24 weeks showed effects similar to those of rabbits fed 0.3 mg KCN/kg BW weekly. Specihc effects produced by linamurin and KCN included elevated lactic acid in heart, brain, and liver reduced glycogen in liver and brain and marked depletion in brain phospholipids (Padmaja and Panikkar 1989). 

A somewhat similar configurational correlation between (leva)-glyceraldehyde and (dexfro)-lactic acid has been made by Wolfrom, Lemieux, Olin and Weisblat.36 Reductive desulfurization of tetra-acetyl-2-methyl-D-glucose diethyl thioacetal (XXVII) and hydrolysis of the product gave 2-methyl-l-desoxy-D-glucitol (XXVIII) oxidation... 

But if it is esterified with some optically active alcohol (ROH ) and then reduced, the resulting ester on hydrolysis yields an optically active lactic acid. 

---