Process for producing 3-iminonitriles

Abstract: A process for producing a 3-iminonitrile represented by the following general formula (II): wherein R₁ and R₂, which may be the same or different, each represents a hydrogen atom, a halogen atom, an aliphatic group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkylamino group, an anilino group, an alkylthio group, an arylthio group, a heterocyclic oxy group, a heterocyclic thio group or an azolyl group, or R₁ and R₂ are bound to each other to form a ring, and M represents an alkali metal, which comprises reacting a compound represented by the general formula (I): wherein R₁ and R₂ are the same as defined for the general formula (II), with an alkali metal hydride; and a process for producing a 3-iminonitr8le represented by the general formula (III): wherein R₁ and R₂ are the same as defined for the general formula (I), which comprises mixing the compound represented by the foregoing general formula (II), which was obtained by the reaction between the compound represented by the foregoing general formula (I) and the alkali metal hydride, with a protic solvent, are disclosed.

Description: This invention relates to a process for producing 3-iminonitriles and, more particularly, to a process for producing 3-iminonitriles useful as intermediates for synthesizing photographic couplers or medicines. 3-Iminonitriles are useful as intermediates for synthesizing photographic couplers or medicines. For example, 3-iminobutyronitrile which is a 3-iminonitrile is used in JP-A-59-171956 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") corresponding to US-A-4,540,654 as a starting material for synthesizing 1H-pyrazolo[1,5-b]-1,2,4-triazoles useful as photographic magenta couplers. As to synthesis of the 3-iminonitriles, descriptions are given in Journal of the American Chemical Society , 64 , 150 (1942), FR-A-1,377,891, Canadian Journal of Chemistry , 43, 332 (1965), and AT-A-375,067, disclosing, for example, the following synthesizing processes: However, these processes result in the undesired production of poisonous sodium prussiate. In addition, in actual production, a step of removing the sodium prussiate is inevitably involved, and therefore the processes involve an additional problem in that the production costs of the 3-iminonitriles becomes seriously high. It is therefore the object underlying the present invention to overcome these drawbacks in the known processes for producing 3-iminonitriles, in particular to provide 3-iminonitriles with producing substantially no sodium prussiate and, therefore, to synthesize 3-iminonitriles stably and inexpensively. According to the present invention this is attained with a process for producing a 3-iminonitrile represented by the following general formula (II): wherein M represents an alkali metal, which comprises reacting a compound of the formula (I): CH₃CN (I) with an alkali metal hydride. In addition, the present invention provides a process for producing a 3-iminonitrile represented by the general formula (III): which comprises mixing the compound represented by the general formula wherein M represents an alkali metal, with a protic solvent, wherein said compound represented by the general formula (II) is obtained by reacting a compound represented by the formula (I): CH₃CN (I) with an alkali metal hydride. In the present invention, compounds represented by the general formula (III) are considered to be isomerized to 3-aminocrotononitriles. An embodiment of the present invention is now described in detail below. Synthesis steps of the present invention are shown by the following process (1): wherein M in the general formulae (II) and (III) are the same as defined hereinbefore. The compound represented by the formula (I) is commercially available or the compound may be readily synthesized according to known processes as described in, for example, "Shin Jikken Kagaku Koza", Vol. 14, pp. 1428 to 1484 (1978). Alkali metal hydrides are preferably used in an amount of from 0.5 to 5.0 molar equivalents, more preferably 0.5 to 1.1 molar equivalents, based on the compound represented by the formula (I). Preferable metal hydrides include lithium hydride, sodium hydride and potassium hydride, with sodium hydride being particularly preferred. As a reaction solvent to produce the compound of the general formula (II), any of commonly known aprotic solvents with high or low polarity may properly be selected and used alone or as a mixture thereof. The amount of the solvent is not particularly limited, but it is preferably used in an amount of from 2 to 10 times as much as the compound of the formula (I) by weight. The reaction solvent is preferably an amide series solvent (e.g., N,N-dimethylformamide or N,N-dimethylamide), an ether series solvent (e.g., tetrahydrofuran or dioxane), an aromatic hydrocarbon series solvent (e.g., benzene, toluene or xylene) or an aliphatic hydrocarbon series solvent (e.g., hexane or octane). A reaction temperature ranging from 0°C to 200°C is preferred, with a range of from 20°C to 150°C being more preferred. The reaction time is preferably 30 min to 10 h with 1 h to 5 h being more preferable. However, since the reaction time varies depending upon, e.g., the scale of the reaction it is not limited to the above-described range. The reaction can be conducted under atmospheric pressure. Compounds represented by the general formula (III) can be obtained by mixing the compound obtained by the above-described reaction and represented by the general formula (II) with a protic solvent such as water. The compound of formula (II) need not be isolated from the a protic solvent used in the above reaction before mixing with a protic solvent. The protic solvent is preferably used in an amount of at least 2 times as much as the amount of alkali metal hydride used in molar ratio, more preferably in an amount 3 to 5 times as much as the compound represented by the formula (I) by weight. The mixing procedure is conducted at a temperature of preferably from 0°C to room temperature under atmospheric pressure. The 3-iminonitriles obtained according to process (1) described above can be separated from the reaction solution in a conventional manner but, if necessary, they may be used as the starting materials for the subsequent reaction without separation. As a suitable isolating means, for example, recrystallization, solvent extraction, filtration, column chromatography and thin layer chromatography may be used independently or in a proper combination. The present invention is now illustrated in greater detail by reference to the following examples. Unless otherwise indicated, all percents, ratios, parts, etc. are by weight. EXAMPLE 1 Synthesis of illustrative compound (1) 9.6 g (2.39×10⁻¹ mol) of sodium hydride (60% dispersion in mineral oil) were added to 75 ml of toluene and, under heat-refluxing and stirring, 25 ml (4.79×10⁻¹ mol) of acetonitrile were dropwise added thereto. Refluxing under heat was continued for an additional 3 h. Thereafter, a precipitate was collected by filtration, and the precipitate was dispersed in diethyl ether, followed by adding water thereto. Then, the organic phase was separated and dried over Glauber's salt, and diethyl ether was distilled off under reduced pressure to obtain 14.5 g of crystals containing the illustrative compound (1). EXAMPLE 2 The synthesis of illustrative compound (1) as well as the preparation of 5-amino-4-chloro-3-methyl-1H-pyrazole hydrochloride (B) which is useful as an intermediate for a photographic coupler from the resulting compound (1) are shown below. 115 g (3.00 mol) of sodium hydride (62.5% dispersion in mineral oil) were added to 922 ml of acetonitrile, and the resulting mixture was stirred while heating at 60 to 70°C for 2 h. Thereafter, 300 ml of water and 200 ml of hexane were added to the mixture at a temperature of 30 to 40°C. The reaction mixture was separated into three layers, and the intermediate layer was isolated and acetonitrile was distilled off therefrom under reduced pressure. 225 g (3.60 mol) of 80% hydrazine hydrate were added to the residue, and the mixture was heated with stirring at 80°C for 1 h and then at 110 to 115°C for 2 h. After allowing to cool, 175 ml of acetone were added to the mixture. After heating the mixture at 60°C for 1 h while stirring, 40 ml of toluene were added thereto, and the solvent was distilled off under reduced pressure. 420 ml of 36% aqueous hydrochloric acid and 80 ml of water were added to the residue, and 361 ml of sulfuryl chloride were added dropwise thereto over 1 h while maintaining the reaction system at a temperature of 30°C or below, during which time crystals precipitated from the reaction system. Then, the reaction mixture was stirred for 4 h while maintaining the temperature at 20°C or below. Thereafter, the generated SO₂ was removed by an aspirator for 2 h under reduced pressure. The pressure of the reaction system was allowed to raise to atmospheric pressure, and 300 ml of acetone were added thereto, followed by stirring at 6°C for 2 h. The filter cake obtained by filtering the reaction mixture was washed with 300 ml of acetone and dried to obtain 337 g of 5-amino-4-chloro-3-methyl-1H-pyrazole hydrochloride (B). A pyrazoloazole coupler can be prepared from the compound (B), for example, according to the procedure as described in Example 3 at columns 30 to 31 of U.S. Patent 4,540,654. Pyrazoloazole series couplers can also be synthesized from the 3-iminonitriles produced according to the present invention by, for example, a process shown as process (2) below, starting with the compound represented by the general formula (III). wherein R represents a substituent such as alkyl or aryl. The process of the present invention enables one to synthesize 3-iminonitriles with more safety and more inexpensiveness than the conventional processes. Therefore, use of the 3-iminonitriles as intermediates for synthesizing photographic couplers or medicines and agricultural chemicals is feasible.

Claims: A process for producing a 3-iminonitrile represented by the following general formula (II): wherein M represents an alkali metal, which comprises reacting a compound of the formula (I): CH₃CN (I) with an alkali metal hydride. The process of claim 1, wherein said alkali metal hydride is lithium hydride, sodium hydride or potassium hydride. The process of claim 1, wherein said alkali metal hydride is used in an amount of from 0.5 to 5.0 molar equivalent based on the compound represented by formula (I). The process of claim 1, wherein said reaction is conducted in the presence of a solvent for 30 min to 10h. The process of claim 1 wherein said reaction is conducted at a temperature of from O o C to 200 o C. The process of claim 5 wherein said reaction is conducted at a temperature of from 20 o C to 150 o C. A process for producing a 3-iminonitrile represented by the general formula (III): which comprises mixing the compound represented by the general formula wherein M represents an alkali metal, with a protic solvent, wherein said compound represented by the general formula (II) is obtained by reacting a compound represented by the formula (I): CH₃CN (I) with an alkali metal hydride. The process of claim 7 wherein said alkali metal hydride is lithium hydride, sodium hydride or potassium hydride. The process of claim 7 wherein said protic solvent is used in an amount of at least 2 times as much as the amount of the alkali metal hydride used in molar ratio.

Inventors: MIZUKAWA YUKI, SATO TADAHISA, TANIGUCHI MASATO, MIZUKAWA, YUKI, SATO, TADAHISA, TANIGUCHI, MASATO
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1989
Main classification: C07C255
IPC codes: C07D307, C07C255, C07C319, C07F1, C07D309, C07C323, C07D521, C07D257, C07C253