Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1973-10-05
1976-03-30
Raymond, Richard L.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
260308R, 260393, 260514J, 260519, 260534R, 260534E, C07C 9900
Patent
active
039474933
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of maleamic acids in suspension.
Various processes for the preparation of maleamic acids are known including those described in U.S. Pat. Nos. 2,444,536 and 2,723,991 and in the work by L. A. Flett and W. H. Gardner entitled "Maleic Anhydride Derivatives".
One of these known processes involves reacting maleic anhydride with a primary amine in the presence of an organic diluent which makes it possible to remove the heat produced by the exothermic reaction. In this way, a very viscous, thixotropic dispersion which is difficult to pour is obtained and from which the maleamic acid produced can be isolated only with great difficulty by means of the usual processes.
We have now found a new process for the preparation, in suspension, of maleamic acids which has, especially in the case of bis-maleamic acids, numerous advantages both with regard to the ease with which the reaction can be carried out either discontinuously or continuously and the ease with which the maleamic acid can be isolated.
The present invention provides a process for the preparation, in suspension, of a maleamic acid of the general formula ##EQU2## in which: R represents a linear or branched alkylene radical, an arylene radical, an aralkylene radical, an alkylarylene radical, a cycloalkylene radical or a divalent heterocyclic radical, the two free valencies of the heterocyclic radical being carried by carbon atoms, the total number of carbon atoms in the R radical being not more than 20, the minimum number of carbon atoms in the alkylene radical being 2 and X represents either hydrogen or a radical ##EQU3## wherein a solution of a primary monoamine or diamine in a solvent is run into a solution of maleic anhydride in a solvent in an amount such that there is an anhydride excess of 5 to 20 mol % relative to the theoretical amount necessary for the reaction with the amine, the mixture is agitated, the reaction temperature is 40.degree. to 130.degree.C., the time taken to run in the amine solution is at least 67 minutes, and the amine solution is run in at a rate such that the slope of the curve representing the variation, as a function of time, in the rate of running in as % of the total amount of amine solution employed per minute (acceleration) has, at every point on this curve, a value not greater than 0.044.
It is also possible, after having manufactured a first quantity of maleamic acid according to the process described above, to proceed with the manufacture continuously by thereafter introducing the reagents simultaneously and continuously into the medium thus produced, heated and stirred, the amine solution being supplied at a rate at most equal to the maximum rate defined above and the anhydride solution in an amount such that the molar ratio anhydride/amine is between 1.05 and 1.2 or 2.1 and 2.4 depending on whether the preparation of a mono- or bis-maleamic acid is involved.
The maleic anhydride is advantageously dissolved in an anhydrous organic solvent such as one of those mentioned below, in proportions such that the concentration of the anhydride solution is between 20 and 30% by weight.
R may be a pure hydrocarbon (or heterocyclic) radical or a hydrocarbon radical interrupted by hetero atoms e.g. --O-- or --SO.sub.2 --. Primary amines which can be used include aniline, ethylene-diamine, hexamethylene-diamine, meta-phenylene-diamine, para-phenylene-diamine, benzidine, diamino-diphenyl-methanes, diamino-diphenyl ethers, diamino-diphenyl-sulphones, diamino-dicyclohexyl-methanes, diamino-dimethylene-cyclohexanes, diamino-meta-xylylenes, diamino-para-xylylenes, diamino-diphenyl-cyclohexanes, diamino-diphenyl-propanes, diamino-triphenyl-ethanes, diamino-triphenyl-methanes and diamino-triazoles.
Of the organic solvents which can be used, those which have a boiling point of between 40.degree.C and 130.degree.C are very suitable. Such solvents include hydrocarbons such as benzene, toluene and cyclohexane, chlorinated hydrocarbons such as chlorobenzene or methylene chloride, c
REFERENCES:
fieser, L. F. Reagents for Organic Synthesis, (1967) pub. by John Wiley & Sons, Inc., p. 845.
Balme Maurice
Gruffaz Max
Raymond Richard L.
Rhone-Poulenc S.A.
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