Glycohc acid

Sodium Chloroacetate Sodium chloroacetate [3926-62-3] mol wt 116.5, C2H2C102Na, is produced by reaction of chloroacetic acid with sodium hydroxide or sodium carbonate. In many appHcations chloroacetic acid or the sodium salt can be used interchangeably. As an industrial intermediate, sodium chloroacetate may be purchased or formed in situ from free acid. The sodium salt is quite stable in dry soHd form, but is hydrolyzed to glycoHc acid in aqueous solutions. The hydrolysis rate is a function of pH and temperature (29). 

Glycohc acid is soluble ia water, methanol, ethanol, acetone, acetic acid, and ethyl acetate. It is slightly soluble ia ethyl ether and spatingly soluble ia hydrocarbon solvents. 

Glycohc acid also undergoes reduction or hydrogenation with certain metals to form acetic acid, and oxidation by hydrogen peroxide ia the presence of ferrous salts to form glyoxylic acid [298-12A], HCOCOOH, and ia the presence of ferric salts ia neutral solution to form oxaHc acid, HOOCCOOH formic acid, HCOOH and Hberate CO2 and H2O. These reduction and oxidation reactions are not commercially significant. 

In appHcations as hard surface cleaners of stainless steel boilers and process equipment, glycoHc acid and formic acid mixtures are particularly advantageous because of effective removal of operational and preoperational deposits, absence of chlorides, low corrosion, freedom from organic Hon precipitations, economy, and volatile decomposition products. Ammoniated glycoHc acid Hi mixture with citric acid shows exceUent dissolution of the oxides and salts and the corrosion rates are low. 

Glycohc acid [79-14-1], HOOCCH2OH, mol wt 76.05, can be obtained by the electrolytic reduction of oxaUc acid or the catalytic reduction of oxaUc acid with hydrogen in the presence of a mthenium catalyst. Because of its acidity it is used as a cleaning agent for metal surface treatments and for boiler cleaning. It also serves as an ingredient in cosmetics (qv). 

Other monoaHyl esters are esters of caproic acid and amyl glycoHc acid, which are used as perfumes. 

Poly(vinyl alcohol) also reacts with monochloroacetates to yield glycoHc acid ethers (160) ... 

With Formaldehyde. The sulfuric acid cataly2ed reaction of formaldehyde [50-00-0] with carbon monoxide and water to glycoHc acid [79-14-1] at 473 K and 70 MPa (700 atm) pressure was the first step in an early process to manufacture ethylene glycol [107-21-1]. A patent (58) has described the use of Hquid hydrogen fluoride as catalyst, enabling the reaction to be carried out at 298 K and 7 MPa (70 atm) (eq. 18). 

Ogawa Y, Yamamoto M, Okada H, Yashiki T, Shimamoto T. A new technique to efficiently entrap leuprolide acetate into microcapsules of polylactic acid or copolyflactic glycohc) acid. Chem Pharm Bull 1988 36 1095-1103. 

Many plants contain a variety of free acids such as acetic acid, citric acid, fumaric acid, malic acid, succinic acid, oxalic acid, glycohc acid, etc. They are components of citric cycle, whereas the others are intermediates in the pathway from carbohydrates to aromatic com-pounds. Following extraction, organic acids can be separated and detected with a variety of techniques. Thin layer chromatographic methods have been also employed to separate certain organic acids,as presented in Table 3. 

In low concentrations, the pH of a glycoHc acid solution varies with the concentration of acid an unbuffered glycolic acid solution, at less than 1%, has a pH of approximately 2.5. At 2%, the pH is 2.1. When the concentration reaches 5%, the pH goes down to 1.9. It is 1.7 for a 10% unbuffered glycolic acid solution. Higher concentrations, 50-80%, have a pH close to 0.5. At identical pH about 0.5, a solution with a concentration of 80% is more aggressive than a 50% solution. 

Fig. 6.15. Possible by-prodncts in the catalytic oxidation of glyoxal (adapted from [379]). Note The production of glycohc acid depends only on the pH by Caimizzaro dismutation and is thus truly homogeneous...

Some of the most promising systems for the controlled release of proteins and peptides involve encapsulation or entrapment in biocompatible polymeric materials. The most widely used polymers to date are poly(ethylene glycol) (PEG), (D,L)-poly(lactic glycohc acid) (PLGA), poly(lactic acid) (PLA) and chitosan. Polymers could be attached to the protein to incTease the overall molecular weight of the system and so reduce the rate of absorption across the epithehum of the alveoh, or the protein could be encapsulated in the polymeric system and slowly released into systemic circulation. 

Some currently available substances for chemical peeling include a-hydroxy acids (glycohc acid), sahcylic acid, and trichloroacetic acid. Sahcylic acid is lipid soluble and may penetrate into sebum-laden follicles more readily than water-soluble a-hydroxy acids. Salicyhc acid may also have some ability to reduce the inflammatory component of acne. Patients with sensitive skin types tolerate sahcylic acid peels. ... 

Usuki A et al. (2003) The inhihitory effect of glycohc acid and lactic acid on melanin synthesis in melanoma cells. Exp Dermatol 12(Suppl 2) 43-50... 

Fig. 2 The loss of munber average molecular weight, weight loss and formation of lactic acid and glycohc acid as a percentage of the theoretical amount during hydrolysis of polyfiactide-co-glycolide) (50/50). The degradation starts by molecular weight decrease, which is followed by weight loss and formation of monomeric hydroxyacids...

Formic, acetic, oxalic, glycohc acid Formic, acetic, propionic, butyric acid... 

Platinum(II) salts as well as the system Pt(II) + Pt(IV) have been used as catalysts in the oxidation of C-H compounds with various strong oxidants. Thus the reaction of methane with chlorine in water at 125 °C in the presence of platinum chlorides affords methyl chloride which is partially hydrolyzed in situ to methanol [17b], A combination of Pt(II) and metalhc platinum oxidized ethane in the presence of oxygen to a mixture of acetic and glycohc acids [17c,d]. 

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