Title of Invention	PROCESS FOR THE PREPARATION OF MALONONITRILE
Abstract	57] Abstract: A process for the preparation of malononitrile, characterized in that methy lisonitrile is converted, optionally in the presence of acetonitrile, at a temperature of from700°Cto 1000°C.

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The invention relates to a novel process for the preparation of malononitrile or of derivatives of nalononitrile of the general formula I Ln which R1 is hydrogen, an alkyl group or a cycioalkyI group. Malononitrile is a starting material and intermediate of central importance for the preparation of an extremely wide range of, for example, pharmaceutical or agrochemical active ingredients (Ullmann's Encyklopadie der technischen Chemie, 4th revised and expanded edition, Verlag Chemie Wenham, Volume 16, p. 419-423). Although a large number of processes are known for the preparation of malononitrile, the only one to have achieved significance on an industrial scale is the high-temperature reaction of acetonitrile with cyanogen chloride at temperatures above 100°C. the object of the invention was to develop alternative processes with the potential for use on an industrial scale. According to the invention, an isonitrile of the general formula Ln which R2 is hydrogen, an alkyl group or a cycioalkyI group, is converted, optionally in the presence of a litrile of the general formula Ln which R3 is hydrogen, an alkyl group or a cycioalkyI group, at a temperature of from 700°C to 1000°C. An alkyl group is expediently taken to mean a C1-6-alkyl group, namely methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, panty and its isomers or hexyl and its isomers. A preferred alkyl group is methyl. CycioalkyI is expediently a C3-6-cycloalkyl, namely cyclopropyl, cyciobutyl, cyclopentyl or cyclohexyl. Preference is given to the conversion of methylisonitrile using acetonitrile. Since the isomerizes of the general formula II can isomerizes to the corresponding nitrites, it is possible, during their conversion using the nitrides of the general formula III, to obtain derivatives of malononitrile, the R1 group of which can correspond either to the R2 group of the isonitrile or to the R3 group of the nitride. This is of course provided that R2 and R3 are different. Accordingly, such a conversion can produce any mixtures of the derivatives of malononitrile. The isomerizes of the general formula II are either commercially available or can be synthesized by known processes in the literature, e.g. Angew. Chemie, 1965, 77, 492-504 or J. Am. Chem. Soc. , 1981, 103, 767-772, The high-temperature conversion according to the invention preferably proceeds at a temperature of from 800°C to 950°C. The reaction is usually carried out in a tubular reactor, which is optionally provided with suitable packing. The conversion time is generally a few seconds. The malononitrile can be isolated from the reaction product, for example, by extraction using a suitable solvent. Accordingly the present invention process for the preparation of malononitrile, characterized in that methylisonitrile is converted, optionally in the presence of acetonitrile, at a temperature of from 700°C to 1000°C. The corresponding application 249/MAS/99 relates to a process for preparing malononitriie, by converting (2 cyno-N-alkoxy) acetinidoyle at high temperature. Example 1: Synthesis and purification of malononitriie by thermolysis of methyl isocyanide and acetonitrile 2ml of methyl isocyanide were diluted with 3 ml of acetonitrile and, using a syringe, introduced into a vapour stream of an acetonitrile distillation (15 g over 20 minutes) . The vapour stream was introduced into a quartz pyrolysis tube (length 30 cm, internal diameter 2.5 cm) heated to 870°C. The reaction product was collected in a cool trap cooled to -50°C. The cool trap residue was concentrated by evaporation on a rotary evaporator, and the content of the reaction products (516 mg) was determined by 1H-NMR. The crude product was extracted with chloroform. Only malononitrile and succinonitrile was soluble in this extract. Example 2: Synthesis of maXononi.tri.la by thezmolysis of methyl isocyanide and acetonitrile 2 ml of methyl isocyanide were diluted with 3 ml of acetonitrile and, using a syringe, introduced into a vapour stream of an acetonitrile distillation {15 g over 20 minutes) . The vapour stream was introduced into an equilibrated quartz pyrolysis tube (length 30 cm, internal diameter 2.5 cm) heated to 920°C. The reaction product was collected in a cool trap cooled to -50°C. The cool trap residue was concentrated by evaporation on a rotary evaporator, and the content of the reaction products (1400 mg) was determined by 1H-NMR. Malononitrile 40% Succinonitrile 1.5% Fumaronitrile and maleonitrile 9% The following examples were carried out as in Example 2, but at different quartz tube temperatures. WE CLAIM: 1. A process for the preparation of malononitrile, characterized in that methylisonitrile is converted, optionally in the presence of acetonitrile, at a temperature of from 700°C to 1000°C. 2. The process according to claim I wherein the conversion temperature is from 800°C to 950°C. 3. A process for the preparation of malononitrile , substantially as herein above described and exemplified.

Documents:

0250-mas-99 abstract.pdf

0250-mas-99 claims.pdf

0250-mas-99 correspondence-others.pdf

0250-mas-99 correspondence-po.pdf

0250-mas-99 description(complete).pdf

0250-mas-99 form-2.pdf

0250-mas-99 form-26.pdf

0250-mas-99 form-4.pdf

0250-mas-99 form-6.pdf

0250-mas-99 petition.pdf