C hydrolytic

The PEEK resia is gray, crystalline, and has excellent chemical resistance T is ca 185°C, and it melts at 288°C. The unfilled resia has an HPT of 165°C, which can be iacreased to near its melting poiat by incorporating glass filler. The resia is thermally stable, and maintains ductiUty for over one week after being heated to 320°C it can be kept for years at 200°C. Hydrolytic stabiUty is excellent. The resia is flame retardant, has low smoke emission, and can be processed at 340—400°C. Crystallinity is a function of mold temperature and can reach 30—35% at mold temperatures of 160°C. Recycled material can be safely processed. Properties are given ia Table 16. 

Deformylation of the cleavage product yields L-kynurenine, which is the substrate for hydrolytic C—C cleavage by kynureninase, a pyridoxal 5 -phosphate-dependent enzyme. The a-amino group of L-kynurenine is attached to the PLP cofactor, and deprotonation of the a-carbon forms a ketimine linkage, which provides an electron sink to assist C-C hydrolytic cleavage, as shown in Figure 27. 

C. Hydrolytic Cleavage of RNA, DNA, and Simple Phosphodiesters by Metal Complexes... 

Figure 12.19 Mechanism of reversible hydrolysis of silica network in E glass and related fibres. Below 300 °C, the reaction moves to the right but at =350 °C, hydrolytic degradation dominates [35].

Figure 8.20 Probable pathways for nonradical thermal degradation formation oflactide and cyclic oligomers by intramolecular transesterification reactions (a, b), intermolecular transesterification reaction (c), hydrolytic degradation reaction (d), and cis-elimination reaction (e) [2721. (Reproduced with permission from ref [272]. Copyright Elsevier, 2003.)...

Manuf./Distnb. Aldrich http //www.sigma-aidrich.com-, BASF AG http //www.basf.de, Fluka http //www.sigma-aidrich.com Vinylmethyidichlorosilane CAS 124-70-9 EINECS/ELINCS 204-710-3 Synonyms Dichloromethylvinylsilane Methylvinyidichlorosilane Silane, dichloromethylvinyl-Empirical CsHeC Si Formula H2C=CHCH3SiCl2 Properties Colorless to It. brn. liq. m.w. 141.08 dens. 1.087 (20/4 C) b.p. 92-93 C flash pt. 4 C ref. index 1.4270 (20 C) hydrolytically sensitive Toxicology LD50 (IV, mouse) 56 mg/kg, (IP, mouse) 270 mg/kg corrosive causes bums harmful by ing., inh., skin absorp. extremely destmctive to tissue of mucous membranes, upper respiratory tract, eyes, skin inh. may cause spasm/inflamm./edema of larynx/bronchi, chem. pneumonitis, pulmonary edema may cause burning sensation. 

In another investigation of RNA hairpin loops, the labiUty of in-strand phosphodi-ester bonds was compared with that of loop phosphodiesters bonds. Chimeric RNA 12-, 13-, 14-, and 15-mers [e.g. (264), (265), (266), (267)] in which only one residue was an RNA (shown in bold arrow indicates scissile phosphodiester bond) and all the others were 2 -G-methylribonucleotides were synthesized and shown to exist as hairpin loops of four, five, six, and seven base residues, respectively, in buffer at pH 7.0 at 65 °C. Hydrolytic data for a series of 15 such oligomers were generated under those conditions and compared with data for a linear molecule (268). The results revealed that phosphodiester bonds in small hairpin loops are conformationally free to cleave... 

Chu, C.C. Hydrolytic degradation of polyglycolic acid tensile strength and crystallinity study. J. Appl. Polym. Sci. 26, 1727-1734 (1981)... 

Fig. 4 Degradation of PEG cystine polyester at 37°C Hydrolytic cleavage of ester moieties at different pH values (solid symbols). Reduction of disulfides at pH 5.5 (cqch = 5 mmol) (diamonds). From [89]. Copyright Wiley-VCH. Reproduced with permission...

Yuan, Z., Cheng, S., Leitch, M., Xu, C. Hydrolytic degradation of alkahne lignin in hot-compressed water and ethanol. Bioresource Technology 2010, 101, 9308-9313. 

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