6341-85-1Relevant academic research and scientific papers
Method for the extraction of keratin from dead animal skins
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Page/Page column 12, (2008/06/13)
horny substances are removed from hides of dead animals by a process wherein the hides of dead animals are treated with at least one substance of the formula I or at least one corresponding alkali metal, alkaline earth metal, ammonium or phosphonium salt, where R1 and R4 are identical or different and are selected from hydrogen, C6-C14-aryl and C1-C12-alkyl, unsubstituted or substituted by one or more SH or OH groups, R2 and R3 are identical or different and are selected from hydrogen, C6-C14-aryl and C1-C12-alkyl, unsubstituted or substituted by one or more SH or OH groups, at least one radical R2 or R3 not being hydrogen or R1 and R4 not being hydrogen, and it being possible in each case for two vicinal radicals R1 to R4 together to be C3-C10-alkylene, R5 is selected from hydrogen, C1-C12-alkyl, H—C═O or C1-C4-alkyl-C═O, X1, X2, X3 and X4 are selected from OH, SH and NHR5, where, if R1 to R4 contain at least one sulfur atom, at least one radical X1 to X4 is SH, and, if R1 to R4 contain no sulfur atom, at least two radicals X1 to X4 are SH.
Stereochemical course of the biotransformation of isoprene monoepoxides and of the corresponding diols with liver microsomes from control and induced rats
Chiappe,De Rubertis,Tinagli,Amato,Gervasi
, p. 831 - 838 (2007/10/03)
The stereochemical course of the biotransformation of isoprene by liver enzymes from control and induced rats has been determined. Between the two primarily formed metabolites, 2-methyl-2-vinyloxirane (2) and isopropenyloxirane (3), epoxide 2 is rapidly transformed into the corresponding vicinal racemic diol 4, predominantly through a nonenzymatic hydrolysis reaction. At variance, epoxide 3 is mainly biotransformed into the diol 5 by microsomal epoxide hydrolase (mEH) to give, before 50% conversion, selectively (R)-3-methyl-3-butene-1,2-diol, 5. The hydrolysis competes with the oxidation of the monoepoxide 3 to the corresponding diepoxides 6. Epoxidation of 3 catalyzed by P450 is characterized by a moderate stereoselectivity which, however, was strongly dependent on P450 induction. Treatment of rats with phenobarbital (PB) (an inducer of P450 2B1 and 3A) leads to threo-(2R,2'R)-(6 with a high selectivity, while with pyrazole (Pyr) (an inducer of P450 2E1), the formation of both erythro-(2S,2'R)- and threo-(2R,2'R)-6 is favored. The mEH-catalyzed hydrolysis of diepoxides 6 proceeds, although with a moderate turnover rate, with substrate and product diastereo- and enantio-selection by nucleophilic attack on the more substituted oxirane ring to give selectively (2R,3S)-3,4-epoxy-2-methyl-1,2-diol (7). Both diols 4 and 5 may be further oxidized on their double bond by P450. These reactions, which occur at a slow rate and are dependent on P450 induction with PB and Pyr, may be negligible in the overall isoprene biotransformation. On the other hand, the epoxydiol 7, which is formed by hydrolysis of diepoxides 6 but it is itself not hydrolyzable, may play an important role in the isoprene toxicity.
Epoxidation of terminal or electron-deficient olefins with H2O2, catalysed by Mn-trimethyltriazacyclonane complexes in the presence of an oxalate buffer
De Vos, Dirk E.,Sels, Bert F.,Reynaers, Mattias,Subba Rao,Jacobs, Pierre A.
, p. 3221 - 3224 (2007/10/03)
A catalytic amount of an oxalate/oxalic acid buffer strongly enhances the catalytic properties of Mn-tmtacn complexes for epoxidation reactions with H2O2. Especially terminal olefins are easily epoxidized. Yields for e.g. allyl acetate or 1-hexene reach up to 99 % and 65 % on olefin and peroxide basis respectively. The reaction is stereospecific; there are no products of solvolysis.
