Aqueous hexasubstituted guanidinium chlorides and methods for their preparation and use

DETAILED DESCRIPTION ; PREFERRED EMBODIMENTS The hexasubstituted guanidinium (hereinafter sometimes simply "guanidinium" for brevity) chlorides which are the subject of the present invention include all those disclosed in the aforementioned U.
S.
Pat.
No.
5,132,423, the disclosure of which is incorporated by reference herein.
In preferred embodiments, the guanidinium chlorides have the formula ?(R.
sup.
2).
sub.
2 N!.
sub.
3 C.
sym.
Cl.
crclbar.
, (II) wherein R.
sup.
2 is a C.
sub.
1-6 primary alkyl radical or two R.
sup.
2 values with the connecting nitrogen atom form a saturated heterocyclic radical.
Such compounds may be prepared by the above-described three-step method wherein the secondary amine has the formula (R.
sup.
2).
sub.
2 NH.
The first aspect of the invention is chiefly effective for production of compositions comprising hexaethylguanidinium chloride, by reason of its solubility characteristics; however, the invention also contemplates its use for other guanidinium chlorides.
In step A, phosgene is passed into a mixture of amine, water and an organic solvent of low polarity.
Suitable organic solvents include aliphatic and aromatic hydrocarbons and halogenated aromatic hydrocarbons, as illustrated by benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, chlorotoluene, dichlorotoluene and octane.
Aromatic solvents which form azeotropic mixtures with water are preferred; these include benzene, toluene and xylene.
Thus, aromatic hydrocarbons are particularly preferred and toluene is most preferred.
The conditions of the reaction between phosgene and the secondary amine are critical for obtaining a high yield of tetrasubstituted urea.
These conditions include a pH within the range of about 10-13, preferably about 10.
5-12.
5, maintained by the addition of an alkali metal base, typically sodium hydroxide or potassium hydroxide and especially the former; a reaction temperature of about 40-80.
degree.
C.
, preferably about 45-55.
degree.
C.
; and a ratio of equivalents of phosgene to amine in the range of 1