Organic compounds -- part of the class 532-570 series – Organic compounds – Nitrogen attached directly or indirectly to the purine ring...
Patent
1998-12-07
2000-12-19
Ford, John M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitrogen attached directly or indirectly to the purine ring...
C07D23930
Patent
active
061629170
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for the preparation of 4,5,6-trichloro- and 2,4,5,6-tetrachloropyrimidine starting from 3-dimethylarninopropionitrile, to its use and also to a crystalline intermediate product form.
BACKGROUND OF THE INVENTION
According to U.S. Pat. No. 3,509,032, 4,5,6-trichloro- and 2,4,5,6-tetrachloropyrimide are obtained by chlorination of 3-dimethylaminopropionitrile with Cl.sub.2 with irradiation by UV light, it being necessary for the temperature of the chlorination to sometimes be above 150.degree. C., in particular from 180 to 220.degree. C., in order to permit the desired products to form (see column 2, line 51 to 53 and Example 2 and 3). Such high chlorination temperatures are, however, disadvantageous when carrying out the procedure industrially.
According to DE-A 3 900 917, 4,5,6-trichloropyrimidine is prepared from the hydrochloride of 3-dimethylarninopropionitrile in a single-step chlorination at a temperature of from 120 to 130.degree. C. However, some aspects of this procedure can still be improved upon, in particular as regards its suitability for large-scale batches.
Furthermore, most of the processes described in the prior art have the disadvantage that during subsequent distillation insoluble distillation residues are formed, which can only be removed from the distillation vessels at considerable expense. In addition, the resulting products gas very severely during distillation.
The object of the present invention was therefore to provide a process for the preparation of 4,5,6-trichloro- and 2,4,5,6-tetrachloropyrimidines starting from 3-dimethylaminopropionitrile which does not have the above disadvantages.
SUMMARY OF THE INVENTION
We have found a process for the preparation of 4,5,6-trichloro- and 2,4,5,6-tetrachloropyrimidine by reacting 3-dimethylaminopropionitrile with HCl and Cl.sub.2, which comprises
a) in a first reaction step reacting 3-dimethylaminopropionitrile in a solvent, preferably one inert towards HCl and Cl.sub.2, with HCl, preferably from 1 to 6 mol, and Cl.sub.2, preferably from 2 to 4 mol, in each case based on 1 mol of 3-dimethylaminopropionitrile, at a temperature of from -10 to 55.degree. C. and
b) in a second reaction step reacting the reaction mixture from the first reaction step with Cl.sub.2, preferably from 3 to 5 mol, based on 1 mol of 3-dimethylaminopropionitrile used, at a temperature above 55.degree. C., preferably from 65 to 120.degree. C., optionally in the presence of a catalyst, presence of the reaction product from the first reaction step, which is in microcrystalline form with an average crystal size of .ltoreq.10 .mu.m.
DETAILED DESCRIPTION OF THE INVENTION
The solvents which are inert towards HCl and Cl.sub.2 under reaction conditions are preferably taken to mean those which are inert under the specified reaction conditions of the process according to the invention. Examples of suitable solvents are chlorinated, aliphatic and aromatic hydrocarbons, such as chloroform, tetrachloromethane, chlorobenzene, dichlorobenzene, isododecane, phosphorus oxychloride or mixtures thereof. Particular preference is given to phosphorus oxychloride (POCl.sub.3).
The first reaction step of the process according to the invention is preferably carried out at a temperature of from 15 to 25.degree. C. It can, for example, be carried out batchwise or continuously.
The batchwise process variant involves, for example, initially introducing the 3-dimethylarninopropionitrile, preferably in the solvent inert towards Cl.sub.2 and HCl, and passing HCl into it. The amount of HCl to be introduced is generally from 1 to 6 mol, preferably from 3 to 4 mol, based on 1 mol of the 3-dimethylaminopropionitrile used. The resulting HCl adduct of the nitrile is particularly readily soluble in the temperature range according to the invention when the solvent used is phosphorus oxychloride. The heat produced during HCl introduction with HCl adduct formation is preferably dissipated by cooling. This is then followed by the reaction with pr
REFERENCES:
patent: 3509032 (1970-04-01), Beck et al.
patent: 5051507 (1991-09-01), Schundehutte et al.
Chemical Abstracts, vol. 106, No. 28, Abstract No. 176415K (1987).
Angewandte Chemie International Edition vol. No. 3, (month unavailable) 1974, G. Beck, Highly Chlorinated Systems by Ring Closure Reactions, p. 210.
Hardenbicker Georg
Steffan Guido
Bayer Aktiengesellschaft
Ford John M.
Gil Joseph C.
Van Eyl Diderico
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