Degradation formaldehyde

Scheme 69. Degradation of NSC-373965 catalyzed by its degradant, formaldehyde. (Reproduced from Ref. 265 with permission.)...

Urea-formaldehyde resins as binding agents in thermal insulation and textile treatment, as glue in chip board, wood floorings, and lacquers >60-70 Degradation, formaldehyde... 

Products of degradation - formaldehyde, methanol, and methyl formate ... 

Typical aminocarboxyhc acids, unsaturated fatty acids bound in hpids, sugars and some other food components are precursors of many important sensory-active carbonyl compounds. Amino acids produce aldehydes mainly as secondary products of alco-hohc or lactic acid fermentations and during thermal processes by Strecker degradation. Formaldehyde (methanal) is formed from glycine, acetaldehyde (ethanal) from alanine propanal and butanal arise from threonine (Figure 8.3), 2-methylpropanal from valine. 

Methyl Isopropenyl Ketone. Methyl isopropenyl ketone [814-78-8] (3-methyl-3-buten-2-one) is a colorless, lachrymatory Hquid, which like methyl vinyl ketone readily polymerizes on exposure to heat and light. Methyl isopropenyl ketone is produced by the condensation of methyl ethyl ketone and formaldehyde over an acid cation-exchange resin at 130°C and 1.5 MPa (218 psi) (274). Other methods are possible (275—280). Methyl isopropenyl ketone can be used as a comonomer which promotes photochemical degradation in polymeric materials. It is commercially available in North America (281). 

Methylphenol is converted to 6-/ f2 -butyl-2-methylphenol [2219-82-1] by alkylation with isobutylene under aluminum catalysis. A number of phenoHc anti-oxidants used to stabilize mbber and plastics against thermal oxidative degradation are based on this compound. The condensation of 6-/ f2 -butyl-2-methylphenol with formaldehyde yields 4,4 -methylenebis(2-methyl-6-/ f2 butylphenol) [96-65-17, reaction with sulfur dichloride yields 4,4 -thiobis(2-methyl-6-/ f2 butylphenol) [96-66-2] and reaction with methyl acrylate under base catalysis yields the corresponding hydrocinnamate. Transesterification of the hydrocinnamate with triethylene glycol yields triethylene glycol-bis[3-(3-/ f2 -butyl-5-methyl-4-hydroxyphenyl)propionate] [36443-68-2] (39). 2-Methylphenol is also a component of cresyHc acids, blends of phenol, cresols, and xylenols. CresyHc acids are used as solvents in a number of coating appHcations (see Table 3). 

Free formaldehyde is a mixture of formaldehyde, formaldehyde hydrates, and low molecular oligomers. It imparts a characteristic odor to padding bath or padded fabrics (76,77). CeUulosics fabrics are capable of retaining large quantities of free formaldehyde, which are gradually evolved. Because all finishes degrade to some extent, extractable formaldehyde and releasable formaldehyde must be considered with respect to user exposure. 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

It has also been found that there can be interactions between hydrolytic degradation and photochemical degradation. Especially in the case of melamine-formaldehyde cross-linked systems, photochemical effects on hydrolysis have been observed. 

A-methylanonaine, prepared from the natural alkaloid by the action of formaldehyde and formic acid, was isolated as the hydriodide, m.p. 246-7° (dec.). dZ-A-methylanonaine was also synthesised and characterised as the hydriodide, m.p. 244° (dec.), and methiodide, m.p. 210-1°. It is regarded as identical with dZ-rcemerine (p. 314), and it may be noted that the melting-point of the Hofmann degradation product of rcemerine is very similar to that of anonaine (IV NMe NH) (Barger and Weitnauer). "... 

Phenolic degradation, thermal and thermo-oxidative, 418-425 Phenolic-epoxy networks, 413 Phenolic monomers, second-order reaction rate constants of formaldehyde with, 403... 

Paraformaldehyde/DMSO dissolves cellulose rapidly, with neghgible degradation, and forms the hydoxymethyl (methylol) derivative at Ce [ 140-142]. Therefore, cellulose derivatives at the secondary carbon atoms are easily obtained after (ready) hydrolysis of the methylol residue. Additionally, fresh formaldehyde may add to the methylol group, resulting in longer methylene oxide chains, that can be functionahzed at the terminal OH group, akin to non-ionic, ethylene oxide-based surfactants [143,144]. 

The thiophosphate phorate is degraded in aqueous solutions at pH 8.5 to yield diethyl sulfide and formaldehyde, which are formed by nucleophilic attack either at the P = S atom or the methylene dithioketal carbon atom (Hong and Pehkonen 1998). 

An interesting study examined the anodic oxidation of EDTA at alkaline pH on a smooth platinum electrode (Pakalapati et al. 1996). Degradation was initiated by removal of the acetate side chains as formaldehyde, followed by deamination of the ethylenediamine that formed glyoxal and oxalate. Oxalate and formaldehyde are oxidized to CO2, and adsoption was an integral part of the oxidation. 

Jahns T, R Schepp, H Kalytwasser (1997) Purification and characterization of an enzyme from a strain of Ochrobactrum anthropi that degrades condensation products of urea and formaldehyde (ureaform). Can J Microbiol AE. 1111-1117. 

Strain IMB-1 is able to grow at the expense of methyl bromide (Woodall et al. 2001) and belongs to a group of organisms that can also degrade methyl iodide, but are unable to use formaldehyde or methanol (Schaefer and Oremland 1999). It was postnlated that the pathway for chloromethane degradation in this strain was similar to that in Methylobacterium chloromethanicum (McAnulla et al. 2001a). 

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