N , N , N′ , N′ -Tetraalkylchlorformamidiniumchlorides 1a , b react with ω -dimethylaminoalkylamines 19 , 20 to give mixtures of N -( ω -dimethylammonioalkyl)-guanidinium salts 12 , 13 and N -( ω -dimethylaminoalkyl)-guanidinium salts 21 , 22 . These mixtures are transformed to mixtures of the ureas 15 , 17 and N -( ω -dimethylaminoalkyl)-guanidines 23 , 25 on treatment with aqueous sodium hydroxide. The reaction of N -(3-dimethylammoniopropyl)-guanidin 25a with dimethylsulfate in a molar ratio of 1:1 delivers a mixture of the N -(3-dimethylaminopropyl)- N,N,N′,N′,N″,N″- pentamethyl-guanidinium salt 29a and the N -(3-dimethylammoniopropyl)- N,N′,N′,N″,N″- pentamethyl-guanidinium-bis (methylsulfate) 33a . The action of dimethylsulfate on the guanidines 23a , 25a in a molar ratio of 2:1 affords the bisquarternary salts 32a , 33a . Alkylating reagents as methyliodide, benzylbromide, allylbromide and chloroacetonitrile attack N -(2-dimethylaminoethyl)- N′,N′,N″,N″- tetraethylguanidine ( 23b ) in a molar ratio of 1:1 cleanly at the dimethylaminoethylgroup to give the ammonium salts 30a – d . As a strong base the guanidine 23b dehydrochlorinates β -Chlorpropionitrile and chloroacetone under formation of the guanidinium salt 21c . In contrast to this the reaction of ethyl bromoacetate with the N -(2-dimethylaminoethyl)guanidine 23b occurs at the guanidinogroup giving the guanidinium salt 28c . The methylation of the guanidinium chlorides 21a , 22a with dimethyl sulfate affords the bis-quaternary salts 35b , 36b with mixed anions. From the heterocyclic guanidines 14 , 16 and the alkylating reagents benzylbromide and ethyl bromoacetate the heterocyclic guanidinium salts 37a , b , 39a , b can be obtained. The reactions with ethyl chloroformiate proceed in an analogous way giving the guanidinium salts 37c , 39c . The N -alkyl- N,N,N′,N′- tetramethyl-(3-ureidopropyl)guanidinium salts 41a , b can be prepared from the N′,N′,N″,N″- tetramethyl- N′′ -(3-ureidopropyl) guanidine 17a and the alkylating compounds dimethyl sulfate and benzyl bromide. Several compounds obtained that way were transformed to the corresponding tetraphenyloborates and bis(tetraphenylborates), respectively.