632-14-4Relevant articles and documents
PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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, (2010/03/02)
The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
S-oxygenation of thiocarbamides II: Oxidation of trimethylthiourea by chlorite and chlorine dioxide
Chigwada, Tabitha R.,Simoyi, Reuben H.
, p. 1094 - 1104 (2007/10/03)
The kinetics of the oxidation of a substituted thiourea, trimethylthiourea (TMTU), by chlorite have been studied in slightly acidic media The reaction is much faster than the comparable oxidation of the unsubstituted thiourea by chlorite. The stoichiometry of the reaction was experimentally deduced to be 2C1O2- + Me2N(NHMe)C=S + H2O → 2Cl- + Me2N(NHMe)C=O + SO42 + 2H+. In excess chlorite conditions, chlorine dioxide is formed after a short induction period. The oxidation of TMTU occurs in two phases. It starts initially with S-oxygenation of the sulfur center to yield the sulfinic acid, which then reacts in the second phase predominantly through an initial hydrolysis to produce trimethylurea and the sulfoxylate anion. The sulfoxylate anion is a highly reducing species which is rapidly oxidized to sulfate. The sulfinic and sulfonic acids of TMTU exists in the form of zwitterionic species that are stable in acidic environments and rapidly decompose in basic environments. The rate of oxidation of the sulfonic acid is determined by its rate of hydrolysis, which is inhibited by acid. The direct reaction of chlorine dioxide and TMTU is autocatalytic and also inhibited by acid. It commences with the initial formation of an adduct of the radical chlorine dioxide species with the electron-rich sulfur center of the thiocarbamide followed by reaction of the adduct with another chlorine dioxide molecule and subsequent hydrolysis to yield chlorite and a sulfenic acid. The bimolecular rate constant for the reaction of chlorine dioxide and TMTU was experimentally determined as 16 ± 3.0 M-1 s-1 at pH 1.00.
Studies of Methyl Isocyanate Chemistry in the Bhopal Incident
D'Silva, Themistocles D. J.,Lopes, Anibal,Jones, Russell L.,Singhawangcha, Sureerat,Chan, John K.
, p. 3781 - 3788 (2007/10/02)
Following the methyl isocyanate leak from Tank 610 at the Bhopal plant, the residual material from the tank was analyzed for its contents.Approximately 70percent of the residue was comprised of three cyclic materials: 1,3,5-trimethyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione or methyl isocyanate trimer (5), 1,3-dimethyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione or dimethyl isocyanurate (6), and dihydro-1,3,5-trimethyl-1,3,5-triazine-2,4-(1H,3H)-dione or dihydrotrimethyltriazinedione (7).Minor quantities of methyl-substituted ureas, biurets, and amine hydrochlorides were also found.The composition of the residue was replicated very closely by the products obtained when a mixture of methyl isocyanate (84.4percent), chloroform (12.0percent), and water (3.6percent) was heated at 225 deg C under pressure in a stainless steel reactor.Experimental results are consistent with the view that under these conditions methyl isocyanate reacts initially with water to form 1,3-dimethylurea (1) and 1,3,5-trimethylbiuret (2).At temperatures between 100 deg C and 225 deg C these products decompose to reactive intermediates which further react exothermically to form the aforementioned cyclic materials, trimethylurea, and mono-, di-, and trimethylamine hydrochlorides.The decomposition of 1 and 2 is facilitated by the presence of chloroform and metals.Other experiments involving 13C-enriched chloroform have given support to the proposed mechanisms for formation of 6 and 7.
Photolysis of Dimethylcarbamoyl Azide in the Presence of a Cyclic Aminimide
Gibson, Harry H.,Weissinger, Keith,Abashawl, Aida,Hall, Greg,Lawshae, Tom,et al.
, p. 3858 - 3861 (2007/10/02)
Dimethylcarbamoyl azide has been photolyzed in the presence of methyl isocyanate to produce the cyclic aminimide 1,1,4-trimethyl-1,2,4-triazolidine-3,5-dione 1,2-ylide (6) and the azo compound N-(dimethylcarbamoyl)-N,N'N'-trimethylazodicarboxamide (7).The azo compound 7 arises a photolytic reaction between dimethylcarbamoyl azide and aminimide 6.Mechanistic studies support a reaction path involving intermolecular-assisted loss of nitrogen from the azide as a result of interaction with aminimide 6.
THE REACTION OF t-BUTYL HYPOCHLORITE WITH THIOCARBONYL COMPOUND - A CONVENIENT METHOD FOR THE TRANSFORMATION
El-Wassimy, M.T.M.,Jorgensen, K.A.,Lawesson, S.-O.
, p. 1729 - 1734 (2007/10/02)
The reaction of t-butyl hypochlorite with different thiocarbonyl compounds has been studied.Primary thioamides 1a-c give 1,2,4-thiadiazole derivatives.N-Phenylthiourea 4a gives 5-imino-4-phenyl-3-phenylamino-4,5-dihydro-1,2,4-thiadiazoline 15.Secondary and tertiary thioamides 2a-d, N-methyl-2-thiopyrrolidinone 3, N,N'-dicyclohexylthiourea 4b, N,N,N'-trimethylthiourea 4c, 5-ethyl-5-phenylthiobarbituric acid 5, xanthione 7a, Mischler's thioketone 7b, thiocoumarin 8, O-ethylthiobenzoate 9, O,O-diphenylthiocarbonate 10, di-p-tolyl and o-phenylene trithiocarbonates 11 and 12 have all afforded the oxigen analogues.N,N-Dimethyl-S-phenyldithiocarbonate 6 produces a mixture of di-, tri-, and tetrasulfides.A mechanism for the transformation is suggested in accordance with the Hard and Soft Acids and Bases (HSAB) principle.
N-NITROSAMINES AS REAGENTS FOR THE =C=S=C=O TRANSFORMATION
Jorgensen, K. A.,El-Wassimy, M. T. M.,Lawesson, S. -O.
, p. 469 - 474 (2007/10/02)
N-nitrosopiperidine and N-nitroso-N-methylaniline react in acidic solution with thiocarbonyl compounds to give the corresponding carbonyl analogues.Secondary- and tertiary thioamides, xanthione, thio- and dithiobutyrolactone, thiocoumarin, certain thiourea derivatives, dithio-O,O-thiocarbonic, S,S-trithiocarbonic- and N,N disubstituted thiocarbamic esters are all converted into the corresponding O-analogues.Thiobenzamide and N-phenylthiourea yield 1,2,4-thiadiazoles.All the reactions are run with iodide (I-) as NO+-carrier.The kinetics of the reaction have been studied under pseudo-first order conditions, and the reaction rate is proportional to the Pearson's nucleophilicity parameter of ions.The =C=S =C=O transformation is also found to take place in gastric juice.
STRUCTURE DE LA N-METHYL-N-NITROSO-N'-NITROGUANIDINE ET DE LA TRIMETHYL NITROSO UREE: ETUDE PAR RMN 15N
Gouesnard, J. P.
, p. 101 - 106 (2007/10/02)
A 15N NMR study of N-methyl-N-nitroso-N'-nitroguanidine (MNNG) in solution has allowed its structure to be determined.This is then compared with those of two other nitroguanidines.Electronic delocalisation in MNNG is attempted in connection with trimethylnitroso urea.
THE =C=S -> =C=O TRANSFORMATION USING THE SOFT NO(+)-SPECIES
Joergensen, K. A.,Ghattas, A.-B.A.G.,Lawesson, S.-O.
, p. 1163 - 1168 (2007/10/02)
The reaction of NaNO2 in acidic solution with thiocarbonyl compounds has been studied.Secondary- and tertiary thioamides, 1-benzyl-hexahydro-2H-azepine-2-thione, 5-ethyl-5-phenyl thiobarbituric acid, certain thiourea derivatives, 2H-1-benzopyran-2-thione, O,O-diphenyl-thiocarbonic ester, O,S-diphenyl-dithiocarbonic ester, N,N-dimethyl-S-phenyl-dithiocarbamatic ester, N-ethyl-N-phenyl-O-ethyl-thiocarbamatic ester are all converted into the corresponding carbonyl-analogues. 4,4'-Bis(dimethylamino)-thiobenzophenone (Michler's thioketone) gives 3-nitro-4,4'-bis(dimethylamino)-benzophenone at room temperature.At (-10 deg C)-(-5 deg C) the expected oxo compound is obtained as the main product together with 4-(N-nitroso-methylamino)-4'-(dimethylamino)-benzophenone.
SYNTHESIS AND PROPERTIES OF CONDENSED UREIDOMETHYL PHOSPHONIUM SALTS
Frank, Arlen W.
, p. 147 - 152 (2007/10/02)
Urea, N-methylurea, and 1,3-dimethylurea react with tetrakis(hydroxymethylphosphonium chloride (THPC) in molar ratios lower than 4:1, forming condensed quaternary ureidomethyl phosphonium salts.The urea and N-methylurea products are polymeric gels, whereas the 1,3-dimethylurea products are cyclic crystalline solids.Some of the phosphonium salts are interconvertible through condensation or displacement reactions.Hydrolysis of the phosphonium salts, followed by oxidation, yields tertiary phosphine oxides having similar properties.The products were characterized by IR, NMR, an d electron spectroscopy for chemical analysis (ESCA).
