19455-20-0Relevant academic research and scientific papers
Utilising 14C-radiolabelled atom transfer radical polymerisation initiators
Long, Mark,Thornthwaite, David W.,Rogers, Suzanne H.,Bonzi, Gwenaelle,Livens, Francis R.,Rannard, Steve P.
supporting information; experimental part, p. 6406 - 6408 (2010/03/04)
14C-radio-initiated atom transfer radical polymerisations allow direct monitoring of the fate of initiating species.
Bioreversible Protection for the Phospho Group: Bioactivation of the Di(4-acyloxybenzyl) and Mono(4-acyloxybenzyl) Phosphoesters of Methylphosphonate and Phosphonoacetate
Mitchell, Anthony G.,Thomson, William,Nicholls, Dave,Irwin, William J.,Freeman, Sally
, p. 2345 - 2354 (2007/10/02)
The di(4-acetoxybenzyl) ester of methylphosphonate 4 (X = H, R = Me) and the di(4-acyloxybenzyl) esters of methoxycarbonylmethylphosphonate 4 (X = MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) were prepared from the appropriate benzyl alcohol and phosphonic dichloride.At pD 8.0 and 37 deg C, both series of compounds hydrolyse with half-lives greater than 24 h to the corresponding mono(4-acyloxybenzyl) esters 5 (X = H or MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) which were prepared by treatment of the di(4-acyloxybenzyl) esters 4 with sodium or lithium iodide.The mono(4-acyloxybenzyl) esters 5 (X = H, R = Me) and 5 (X = MeO2C, R = Me, Et, Pr, iPr or tBu) undergo chemical hydrolysis to methylphosphonate 6 (X = H), and methoxycarbonylmethylphosphonate 6 (X = MeO2C), respectively, together with 4-hydroxybenzyl alcohol and the appropriate acylate anion.The rates of hydrolysis of the mono(4-acyloxybenzyl) esters decrease as the length and steric bulk of the acyl group increases, with half-lives ranging from ca. 150 h for the acetyl analogues to 2240 h for the pivaloyl derivative.The hydrolyses of the di- and mono-(4-acyloxybenzyl) esters were catalysed by porcine liver carboxyesterase (PLCE), and in all cases the acylate anion was formed.The rate of enzymatic hydrolysis was most rapid for the 4-butanoyloxybenzyl and 4-isobutanoyloxybenzyl analogues.The methoxycarbonyl ester of the phosphonoacetate analogues was not cleaved by PLCE.The methylphosphonate generated from the reaction of 4 (X = H, R = Me) in the presence of esterase and H2(18)O, did not contain (18)O attached directly to phosphorus.These results suggest that both the chemical and enzymatical hydrolyses of themono(4-acyloxybenzyl) esters and the PLCE-catalysed hydrolyses of the di(4-acyloxybenzyl) esters proceed via hydrolysis of the acyl group to give the acylate anion and the unstable 4-hydroxybenzyl esters.The electron-donating 4-hydroxy group facilitates the cleavage of the benzyl-oxygen bond with the formation of the 4-hydroxybenzyl carbonium ion 9, which readily reacts either with water or the phosphate buffer.The 4-acyloxybenzyl phosphoesters provide the first example of a protecting group which will enable the bioactivation of phosphonate prodrugs at rates appropriate to biological systems.
Isolation of Crystalline Potassium Alkanecarboselenoates
Kageyama, Hideki,Takagi, Kazutaka,Murai, Toshiaki,Kato, Shinzi
, p. 1519 - 1523 (2007/10/02)
A series of potassium alkanecarboselenoates (2) were isolated as crystals from the reaction of the corresponding bis(acyl)selenides with potassium methanolate.The salts 2 readily react with alkyl iodides at 0 deg C to afford the corresponding alkyl alkanecarboselenoates (3) in quantitative yields. - Key words: Potassium Alkanecarboselenoates, Potassium Selenocarboxylate, Selenocarboxylic Acid Potassium Salts
Relationship between the Electronic Structure of Acrylic and Methacrylic Acid and the Rates of Hydrogenation of Their Salts on Pt Black
Volkova, L. D.,Vyaznikovtseva, O. V.,Gabdrakipov, V. Z.,Sokol'skii, D. V.
, p. 1650 - 1652 (2007/10/02)
We have studied the hydrogenation of the alkali metal salt of acrylic and methacrylic acid on platinum black.The relative reactivities, which are interest in calculations of the electronic structure of acids, have been determined by the CNDO/2 method.
N,N-dialkyl-N'-(substituted-5-isothioazolyl)-N'-acylureas as herbicides
-
, (2008/06/13)
A new class of herbicidal compounds consisting of N,N-dialkyl-N'-(substituted-5-isothiazolyl)-N'-acylureas in which the 3-substitutent on the isothioazole moiety consists of alkyl, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylamino, and dialkylamino, and the 4-substituent on the isothiazole moiety consists of cyano, alkoxycarbonyl, and nitro; and in which the nitrogen atom of the N,N-dialkylurea to which the isothiazolyl moiety is bonded, is also bonded to an acyl moiety, exhibits outstanding preemergence and postemergence herbicidal activity, controlling effectively the growth of a wide spectrum of grassy and broad-leaved plant species. The synthesis of members of this class is described in detail and the utility of representative compounds is exemplified.
