METHOD FOR PREPARING FLUOROALKYLNITRILES AND THE CORRESPONDING FLUOROALKYLTETRAZOLES

Abstract

The present invention relates to a method for preparing fluoroalkylnitriles and the corresponding fluoroalkyltetrazoles by reacting fluorinated carboxamides with phosphorus trichloride (PCl.sub.3) or phosphorus oxychloride (POCl.sub.3) in the presence of a base.

Claims

1. Method for preparing fluoroalkylnitriles of formula (I), ##STR00007## in which X.sup.1 and X.sup.2 are mutually independently fluorine, chlorine, hydrogen or methyl, comprising reacting one or more fluorinated carboxamides of formula (II) ##STR00008## in which X.sup.1 and X.sup.2 are as defined above, with phosphorus trichloride (PCl.sub.3) and/or phosphorus oxychloride (POCl.sub.3) in the presence of a base.

2. Method according to claim 1, wherein X.sup.1 and X.sup.2 are both fluorine.

3. Method according to claim 1, wherein the molar ratio of phosphorus halide to the fluorinated alkylamide used of formula (II) is 0.05 to 1.

4. Method according to claim 1, wherein the base is selected from the group consisting of pyridine, picoline, quinoline, quinaldine and halogenated pyridines.

5. Method according to claim 1, wherein the molar ratio of base to the fluorinated alkylamide used of formula (II) is 1 to 10.

6. Method according to claim 1, comprising reacting one or more fluoroalkylnitriles obtained of formula (I), ##STR00009## with sodium azide in the presence of a solvent to give the corresponding fluoroalkyltetrazoles of formula (III) ##STR00010## in which X.sup.1 and X.sup.2 are as defined above.

Description

PREPARATION EXAMPLES

Example 1

[0039] ##STR00005##

[0040] A mixture of 148.3 g (1.592 mol, 3.00 eq.) of 3-picoline and 8.1 g (0.053 mol; 0.10 eq.) of POCl.sub.3 was heated to 100 C. To this mixture were metered in 57.0 g (0.372 mol; 0.70 eq.) of POCl.sub.3 and at the same time a mixture of 60.0 g (0.531 mol; 1.00 eq.) of trifluoroacetamide in 98.9 g (1.062 mol; 2.00 eq.) of 3-picoline over a period of 4 hours. Subsequently, the temperature was increased to 125 C. over a period of one hour. The resulting trifluoroacetonitrile is conducted through a reflux condenser and a wash bottle, filled with 3-picoline, and introduced into a mixture of 36.2 g (0.557 mol; 1.05 eq.) of sodium azide and 320.3 g of acetone. The slightly exothermic reaction is carried out at a temperature of 25 C. to 30 C. At the end of the reaction, the excess sodium azide is filtered off and washed with acetone. The filtrate is concentrated to 30% by weight of trifluoromethyltetrazole Na by distillation of acetone under reduced pressure. The theoretical yield is 75%.

Example 2

[0041] ##STR00006##

[0042] A mixture of 150.0 g (1.613 mol; 3.00 eq.) of 3-picoline and 7.3 g (0.053 mol; 0.10 eq.) of PCl.sub.3 was heated to 70 C. To this mixture were metered in 51.0 g (0.372 mol; 0.70 eq.) of PCl.sub.3 and at the same time a mixture of 60.0 g (0.531 mol; 1.00 eq.) of trifluoroacetamide in 100.0 g (1.074 mol; 2.00 eq.) of 3-picoline over a period of 4 hours. Subsequently, the temperature was increased to 80 C. over a period of one hour. The resulting trifluoroacetonitrile is conducted through a reflux condenser and a wash bottle, filled with 3-picoline, and introduced into a mixture of 36.2 g (0.557 mol; 1.05 eq.) of sodium azide and 320.0 g of acetone. The slightly exothermic reaction is carried out at a temperature of 25 C. to 30 C. At the end of the reaction, the excess sodium azide is filtered off and washed with acetone. The filtrate is concentrated to 30% by weight of trifluoromethyltetrazole Na by distillation of acetone under reduced pressure. The theoretical yield is 63%.