Oximes degradation

Dihydrotriazine (83) on acid hydrolysis gives the oxime degradation product (84) <83H(20)839> and the dihydrotriazine (85) decomposes when heated in water to give the ketone (86), acetamide (2.5%) and diacetamide (5%) (Scheme 17) <83JCS(P1)1075>. 

House, J. E. 1989. The development of the LIX reagents. Miner. Metall. Proc. 6(2) l-6. Hurtado-Guzman, C. and Menacho, J. M. 2003. Oxime degradation chemistry in copper solvent extraction plants. In Proceedings hydrometallurgy of copper modelling, impurity control and solvent extraction, vol. 6, book 2, eds. PA. Rivieros, D. G. Dixon, D. 

WOHL - WEYGAND Aldose degradation Degradation of sugar oximes via cyanohydrins by means of an acid chloride/pyridine (Wohl) or of... 

Thebainone (Schopf), CigHjjOgN. This substance, which must be distinguished from Pschorr s thebainone (metothebainone of Schopf (see p. 248) ), is formed, along with the latter in the reduction of thebaine by stannous chloride in hydrochloric acid, and was isolated by Schopf and Hirsch. Its prior isolation by Pschorr, as confirmed by Morris and Small, has been referred to already. It crystallises with 0-5 HjO, has m.p. 151-2°, yields a hydriodide, m.p. 258-9°, methiodide, m.p. 223°, and an oxime, m.p. 185-6°. On catalytic hydrogenation it yields dihydrothebainone (LI), and can be degraded to 3 4 6-triacetoxyphenanthrene, m.p. 165-7°. On this basis formula (XLIX) is assigned to it. The mechanism of the formation of codeinone, thebainone and mefathebainone from thebaine is discussed by Schopf and Hirsch. ... 

In the one application reported for the conversion of the 17jff-acetyl side-chain to the 17-ketone, the intermediate oxime was not isolated, but hydrolyzed in situ with acid in an overall yield of about 20 %. In the case of 17jff-acetyl-D-norandrostanes, which are particularly difficult to degrade to D-norandrostanes, the nitrite procedure proved the most convenient method. The yield is 25 %, nowhere near the much higher yield obtained by a Baeyer-Villiger reaction which, however, must be allowed to proceed for one month at 0°. ... 

Conversion of the aldehyde into a nitrile is accomplished by treatment of an aldose with hydroxvlamine to give an oxime (Section 19.8), followed by dehydration of the oxJme with acetic anhydride. The Wohl degradation does not give particularly high yields of chain-shortened aldoses, but the reaction is general for all aldopentoses and aldohexoses. For example, D-galactose is converted by Wohl degradation into n-lyxose. 

One published stereoselective synthesis uses the base-catalysed cycllsation oi optically active enone (2) with a prolonged reaction time to get cis-(3) which is converted into (1) by degradation of the oxime. 

Oxime carbamates are generally applied either directly to the tilled soil or sprayed on crops. One of the advantages of oxime carbamates is their short persistence on plants. They are readily degraded into their metabolites shortly after application. However, some of these metabolites have insecticidal properties even more potent than those of the parent compound. For example, the oxidative product of aldicarb is aldicarb sulfoxide, which is observed to be 10-20 times more active as a cholinesterase inhibitor than aldicarb. Other oxime carbamates (e.g., methomyl) have degradates which show no insecticidal activity, have low to negligible ecotoxicity and mammalian toxicity relative to the parent, and are normally nondetectable in crops. Therefore, the residue definition may include the parent oxime carbamate (e.g., methomyl) or parent and metabolites (e.g., aldicarb and its sulfoxide and sulfone metabolites). The tolerance or maximum residue limit (MRL) of pesticides on any food commodity is based on the highest residue concentration detected on mature crops at harvest or the LOQ of the method submitted for enforcement purposes if no detectable residues are found. For example, the tolerances of methomyl in US food commodities range from 0.1 to 6 mg kg for food items and up to 40 mg kg for feed items. ... 

Oxime carbamates are generally stable in aqueous solutions at pH 4-6. Their chemical degradation (hydrolysis) in water depends strongly on pH. Strongly basic conditions... 

Investigation following two violent explosions involving the oxime or its derivatives showed that it may be distilled at 152°C at ambient pressure only if highly purified. Presence of impurities, especially acidic impurities (e.g. the oxime hydrochloride) drastically lowers the temperature at which degradation occurs. 

The salt undergoes violent degradation at 50-70°C, and its presence in trace quantities may promote degradation of the oxime. 

Dining preparation of tris(ketoximino)silanes, two violent explosions attributed to acid-catalysed exothermic rearrangement/decomposition reactions occurred. Although these silane derivatives can be distilled under reduced pressure, the presence of acidic impurities (e.g. 2-butanone oxime hydrochloride, produced during silane preparation) drastically reduces thermal stability. Iron(III) chloride at 500 ppm caused degradation to occur at 150°, and at 2% concentration violent decomposition set in at 50°C. 

Rajagopal et al. (1984) used numerous compounds to develop a proposed pathway of degradation of aldicarb in soil. These compounds included aldicarb oxime, A-hydroxymethyl aldicarb, A-hydroxymethyl aldicarb sulfoxide, A-demethyl aldicarb sulfoxide, A-demethyl aldicarb sulfone, aldicarb sulfoxide, aldicarb sulfone, A-hydroxymethyl aldicarb sulfone, aldicarb oxime sulfone, aldicarb sulfone aldehyde, aldicarb sulfone alcohol, aldicarb nitrile sulfone, aldicarb sulfone amide, aldicarb sulfone acid, aldicarb oxime sulfoxide, aldicarb sulfoxide aldehyde, aldicarb sulfoxide alcohol, aldicarb nitrile sulfoxide, aldicarb sulfoxide amide, aldicarb sulfoxide acid, elemental sulfur, carbon dioxide, and water. Mineralization was more rapid in aerobic surface soils than in either aerobic or anaerobic subsurface soils. In surface soils (30 cm depth) under aerobic conditions, half-lives ranged from 20 to 361 d. In subsurface soils (20 and 183 cm depths), half-lives under aerobic and anaerobic conditions were 131-233 and 223-1,130 d, respectively (Ou et al, 1985). The reported half-lives in soil ranged from approximately 70 d (Jury et ah, 1987) to several months (Jones et al, 1986). Bromilow et al. (1980) reported the half-life for aldicarb in soil to be 9.9 d at 15 °C and pH 6.34-7.0. 

Groundwater. In Florida groundwater, aldicarb was converted to aldicarb sulfoxide under aerobic conditions. Conversely, under anaerobic conditions (pH 7.7), oxidative metabolites (aldicarb sulfoxide and aldicarb sulfone) reverted back to the parent compound (aldicarb). Half-lives in unfiltered and filtered groundwater were 635 and 62 d, respectively (Miles and Delfino, 1985). In sterile anaerobic groundwater at pH 8.2, aldicarb slowly hydrolyzed to the aldicarb oxime. In a microorganism-enriched groundwater at pH 6.8, aldicarb rapidly degraded to... 

CASRN 59669-26-0 molecular formula C10H18N4O4S3 FW 354.47 Soil In aerobic and anaerobic soil, thiodicarb degrades to methomyl and methomyl oxime (Hartley and Kidd, 1987). The reported half-life in various soils is 3-8 d (Hartley and Kidd, 1987). 

Miles, C.J., Trehy, M.L., and Yost, R.A. Degradation of A-methylcarbamate and carbamoyl oxime pesticides in chlorinated water. Bull. Environ. Contam. Toxicol, 41(6) 838-843, 1988. 

New azacyclic diterpenoid compounds were also prepared in good yields by ring expansion and only one isomer of the lactam 363 product was obtained (equation 142). However, when the oxime was tosylated, a nitrile compound resulting from ring opening was obtained in good yield (72%) as a result of the Beckmann degradation reaction. 

D-Fucose (Rhodeose). Voto6ek obtained tetraacetyl-D-fucononitrile in 25% yield by treating D-fucose oxime with sodium acetate-acetic anhydride. The nitrile, degraded with ammonia and silver oxide, yielded 5-desoxy-D-lyxose diacetamide in 40% yield. The diacetamide compound was hydrolyzed with 5% hydrochloric acid and the 5-desoxy-D-lyxose was obtained in solution and characterized as the p-bromo-phenylosazone. Hydrolysis of the diacetamide compound with 6 N sulfuric acid was realized by Voto6ek and Valentin and the 5-desoxy-D-lyxose was isolated as a sirup. 

Tetrabenzoyl-L-rhamnononitrile was prepared by Restelli de Labriola and Deulofeu in 91 % yield from the oxime with pyridine and benzoyl chloride, and was degraded to 5-desoxy-L-arabinose dibenzamide in very small yield (13%) by treatment with ammonia in ethanol. 

D-Galactose. Wohl and List prepared pentaacetyl-n-galactononitrile from the oxime in 40% yield. Degradation with ammonia-silver oxide gave 40% of n-lyxose diacetamide. Hydrolysis of the diacetamide with... 

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