Patent GB-769711-A (GB)
Title: Improvements in or relating to substituted tetrazolines and methods for obtaining the same
Filed: 1954-08-27
Abstract: The invention comprises 1-alkyl-4-aralkyl-5-imino-D 2-tetrazolines of the general formula <FORM:0769711/IV(b)/1> and acid addition salts thereof, wherein X and Y are the same or different and represent hydrogen or a halogen, or a hydroxy, alkyl (1-4 carbon atoms), alkoxy (1-4 carbon atoms) or nitro group, Z is a divalent alkylene group containing from 1 to 4 carbon atoms, and R is an alkyl group containing from 5 to 17 carbon atoms, and the preparation thereof by condensing a 5-aminotetrazole of the formula <FORM:0769711/IV(b)/2> wherein P is an alkyl radical containing 5 to 17 carbon atoms or an aralkyl radical of the formula <FORM:0769711/IV(b)/3> with an aralkyl halide of the formula <FORM:0769711/IV(b)/4> in the case where P represents the alkyl radical, Hal representing a halogen and X and Y having the above significance, or with the required alkyl halide in the case where P represents the aralkyl radical, in the presence of a base, or by carrying out the above condensation in the absence of a base whereby a hydrohalide salt of the desired tetrazoline is formed. The invention also includes a process for the preparation of the above tetrazolines by treating the corresponding hydrohalide salts with a base, and a process for the preparation of salts of the above tetrazolines by treating the desired tetrazolines with at least one equivalent of an acid.  The condensation may be carried out in the presence of an inert organic solvent such as benzene, xylene, toluene, ethanol, butanol or isopropanol.  Suitable bases which may be present in the reaction mixture are organic and inorganic bases such as pyridine, triethylamine, potassium carbonate, sodium bicarbonate and N-ethylpiperidine.  Reaction temperatures may vary from 50 DEG  to 160 DEG  C., a temperature between 110 and 150 DEG C. preferably 120 DEG  to 130 DEG  C. being particularly suitable when no reaction solvent or base is employed.  Acid addition salts mentioned are the hydrochloride, hydrobromide, sulphate, acetate, tartrate, citrate and sulphamate salts.  In the examples a large number of D 2-tetrazolines of the above general formula are prepared in which R represents the n-amyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-tridecyl, n-tetradecyl, n-pentadecyl and n-heptadecyl radicals, and <FORM:0769711/IV(b)/5> represents the benzyl, o- and p-chlorobenzyl, p-bromobenzyl, 2,4- and 3,4-dichlorobenzyl, p-ethyl-, p-nitro-, p-methoxy- and 2-hydroxy-4-nitro-benzyl, o-, m- and p-xylyl, b -phenyl-ethyl, g -phenylpropyl and d -phenylbutyl radicals, and salts of these D 2-tetrazolines.  The preparation of the following starting compounds is given 1-Alkyl- and 1-aralkyl-5-aminotetrazoles in which the alkyl radical has from 5 to 17 carbon atoms and the aralkyl radical is of the formula <FORM:0769711/IV(b)/6> wherein X, Y and Z have the above significance, are prepared by reacting the required alkyl or aralkyl cyanide with hydrazoic acid in the presence of a strong mineral acid, such as sulphuric acid, at a temperature between about 30 DEG  and 50 DEG  C.  The preparation of 1-n-octyl-5-aminotetrazole is detailed.