摘要:
A process is described for the synthesis of 2-hydroxy-4-alkyloxy benzophenone by the selective alkylation of 2,4-dihydroxy benzophenone with a dialkyl carbonate, in liquid phase, in the presence of suitable catalysts, at a temperature ranging between 120.degree. and 220.degree. C. and at a total pressure ranging from 2 to 60 ate.
摘要:
The invention relates to the use of organic carbonates having formula (I) wherein: n=1-4 R and R′ are two linear or branched alkyl radicals which contain a number of carbon atoms whose sum is equal to at least 5 and which can be the same or different, as solvents for the washing of metal surfaces.
摘要:
A process for the alkylation of imides wherein the imides are reacted with a dialkyl carbonate, in the liquid state, at a temperature of between 100.degree. C. and 250.degree. C. and at a pressure of between 0 and 60 atmospheres in the presence of a basic catalyst. The dialkyl carbonate reagents are not very toxic and are thermally stable and their use as alkylation agents makes it possible to produce waste products with a negligible saline content.
摘要:
Multistep process for the preparation of alkyl mono and diisocyanates consisting in reacting the corresponding aliphatic amine or diamine with dimethylcarbonate and, substantially, in partially vaporizing and converting the urethane thus formed in an evaporator to subsequently terminate the cracking in a II.degree. reactor, and finally subjecting the cracking product to fractional distillation at reduced pressure, recycling the unconverted part to the partial vaporization step.
摘要:
A process for preparing carbamates is disclosed, in which:a stoichiometric or higher-than-stoichiometric amount of an alkyl carbonate or a cycloalkyl carbonate is reacted with an aliphatic, cycloaliphatic or aromatic amine, in a first reaction step, by operating in the presence of a carbamation catalyst, in order to produce a mixture of a carbamate and an urea,the urea contained in the reaction product from the first process step is reacted with carbonate, in a second reaction step, in order to produce the corresponding carbamate, andthe reaction mixture coming from the second process step is submitted to treatments in order to recover the carbamate.The process makes it possible high yields and high values of selectivity to the useful reaction product to be obtained.
摘要:
A process is provided for the preparation of N-alkyl-carbamates by directly reacting low-molecular weight alkyl-isocyanates, in particular methyl isocyanate, and a substituted phenolic precursor in solution in the presence of a basic catalyst compound selected from the class of bicyclic amidines or bicyclic guanidines.
摘要:
New procedure for the preparation of polyoxazolidines which can be defined with the general formula: ##STR1## This procedure, which excludes the use of isocyanates, requires the simple transesterification of the dicarbamate of a diamine with an N-hydroxyalkyloxazolidine.
摘要:
A composition of matter for inhibition of stress corrosion of stainless steels in contact with aqueous and/or polar organic solutions which contain chloride ions and optionally cuprous ions, comprising an aqueous or polar organic solution of a member selected from the group consisting of quaternary ammonium alkylcarbonates and quaternary ammonium benzylcarbonates having the general formula: ##STR1##
摘要:
Integrated process for the preparation of aromatic isocyanates comprising: the reaction between an aromatic amine and an organiccarbonate in the presence of a catalyst selected from organic and inorganic salts of a metal selected from Zn, Sn, Pb, Cu; the removal of the catalyst; the passivation of the quantity of residual metal in the urethane formed in step a); the removal of the organic solvent and its optional recycling to step a) of the reaction; the evaporation of the aromatic urethane with partial pyrolysis; the complete pyrolysis of the urethane in gas phase; the recovery of the isocyanate.
摘要:
A process is described for the preparation of polycarbonate dials (PCD) with a high molecular weight comprising two subsequent reaction steps, wherein in the first step PCD with a molecular weight ranging from 500 to 2000, is synthesized and in the second step the molecular weight of the PCD is increased to the desired value. Polycarbonate diols are usefully applied in the field of thermoelastomeric polyurethane manufactured products, paints, adhesives and synthetic leather.