- Contamination of dipeptide by polymer stabilizers leached from gloves and packaging during scale-up
-
In dipeptide production, it was observed that a water solution of a peptide became turbid. The origin of turbidity was monitored and identified by LC-MS analysis. The impurities, derived from natural rubber gloves, and polyethylene bags caused the turbidity when the wet cake of the peptide contacted them.
- Sano, Takahiro,Senzaki, Hirohiko,Sugaya, Toru,Kasai, Masaji
-
-
Read Online
- Catalytic synthesis of triaryl phosphates from white phosphorus
-
Triaryl phosphates were synthesized from white phosphorus and phenols under aerobic conditions and in the presence of iron catalysts and iodine. Full conversion to phosphates was achieved without the use of chlorine, and the reactions do not produce acid waste. Triphenyl phosphate, tritolyl phosphate and tris(2,4-di-tert-butyl)phenyl phosphate were synthesized by this method with high selectivities. Various iron(III) diketonates were used to catalyze the conversion. Mechanistic studies showed that the reaction proceeds by formation of PI3, then O=PI(OPh)2 before the final formation of the phosphate. The nucleophilic substitution of O=PI(OPh)2 with phenol to form O=P(OPh)3 was found to be the rate-limiting step.
- Armstrong, Kenneth M.,Kilian, Petr
-
experimental part
p. 2138 - 2147
(2011/06/28)
-
- FACTORS DETERMINING THE REACTIVITY OF PHOSPHOROUS TRIESTERS IN REACTIONS WITH CUMENE HYDROPEROXIDE
-
The kinetics of reduction of cumene hydroperoxide with a wide range of aliphatic and aromatic phosphorous triesters in benzene were studied by the polarographic method.Factors determining the reactivity of the phosphites in this reaction were investigated by the method of correlation analysis.
- Cherkasova, O. A.,Galkin, V. I.,Sayakhov, R. D.,Mukmeneva, N. A.,Cherkasov, R. A.
-
p. 862 - 865
(2007/10/02)
-
- Organophosphorus Antioxidants. X. The Hydroperoxide Decomposing Action of Phosphites, Phosphonites and Thiophosphites
-
The kinetics and mechanism of reactions of phosphites, phosphonites, thiophosphites and hydrogenphosphites with cumyl (CHP), t-butyl (TBHP) and α-tetralyl (THP) hydrogenperoxides has been studied by means of (31)P-n.m.r. spectroscopy, high performance liquid chromatography and iodometric titration.All three valent phosphorus compounds studied initially react with hydroperoxides stoichiometrically to give the corresponding P=O products and alcohol.Some species are able to decompose cumyl hydroperoxide catalytically to form phenol and aceton.Acyloin phosphites decompose CHP catalytically after a stoichiometric reaction as thiophosphites do.Tetramethylpiperidinyl phosphites ("HALS-phosphites") react with hydroperoxides only stoichiometrically but with high velocity.Phosphonites react with hydroperoxides in the same way as the corresponding phosphites.Their reactivity, however, is much higher.Hydrogenphosphites are less reactive than phosphites in the reaction with hydroperoxides.They are able to act catalytically.
- Koenig, T.,Habicher, W. D.,Schwetlick, K.
-
p. 913 - 922
(2007/10/02)
-
