The B. F. Goodrich Company

Victor L Ledesma

George Kletecka

Pyong-Nae Son

Ronald M Kovach

A process for methylating the N.sup.4 atom of a polysubstituted piperazine or piperazin-2-one ('PSP') is effective despite using a much smaller molar excess of formaldehyde and formic acid than dictated by a conventional Eschweiler-Clarke reaction. Particularly in a complex amine in which the PSP substituent is connected to a triazine ring which in turn may be connected to a N atom of an acyclic polyamine, the molar ratio of NH groups:HCHO:HCOOH is in the range from about 1:1:1 to 1:1.5:1.5, the amount of HCHO and HCOOH being sufficient to methylate at least the &gt;NH groups of said PSP substituent if the complex amine contains terminal --NH groups. The same range of molar ratio is maintained when the total number of NH groups to be methylated includes the terminal --NH groups. The effectiveness of the process is attributed to use of an alkylbenzene solvent in which reaction with only a slight excess of HCHO and HCOOH proceeds apace, and in which solvent the methylated product remains dissolved.

Process for methylating a hindered nitrogen atom in an inert non-aqueous

The prior art solvent process for the manufacture of an oxo-piperazinyl triazine (PIP-T) compound required carrying out the reaction between an appropriately hindered cyclic amine and cyanuric chloride in the presence of caustic catalyst, in alkylbenzene solution, typically toluene. The chloride ions generated during the reaction, in presence of water present in the reaction zone, produced serious corrosion and resulted in off-color product which had a melt absorptivity greater than 3.5 mL/gm.cm. This 'color' in the product made the product generally unmarketable. Another process to make a PIP-T termed 'the solventless' process used no toluene solvent, and no caustic but required such a very large excess of amine that the catalytic function of the amine.HCl salt went unnoticed. In the novel process, referred to as the 'hybrid' process, this catalytic function allows the use of only as much toluene in the reactor as is needed to keep the product formed and the excess amine in solution, and the use of less than a two-fold molar excess over the molar amount to displace each chlorine atom of the cyanuric chloride. The result is exceptionally high purity and yield with color no greater than that which the marketplace accepts.

Hybrid process for preparing a tri-substituted triazine

A process is taught for recovering a white reaction product of a cyanuric halide with an amine reactant (white being indicative of the product's high purity), in high yield. In the absence of a solvent for either reactant, the first step comprises reacting the cyanuric halide, as a finely divided solid, with a liquid amine which is to provide a saturated heterocyclic amine group, such as a polysubstituted piperazinone, piperazine, or piperidine as the substituent for each of the three halogen atoms of the cyanuric halide used. This solventless process carried out under essentially anhydrous conditions, with a large molar excess of the amine reactant chosen, not only shortens the long time required to make the desired tri-substitution in a conventional solvent process, but also obviates using a pressurized reactor. Since (i) the reaction temperature is relatively low, (ii) there is no solvent, and (iii) the amine reactants are relatively high-boiling, and the reaction occurs in the liquid phase, there is no build-up of pressure. Fortuitously, the appropriate amount of alkanol and concentrated aqueous alkali provides a partition coefficient such that salt formed by neutralization of the excess amine hydrohalide is effectively precipitated nearly quantitatively. In addition to providing 'easy' processing conditions, the solventless reaction in our process provides higher yields than can be obtained, under comparable conditions, with the `solvent process`; a lower by-product `make` because of the low temperature and substantially atmospheric pressure used; and, the batch reaction is completed in less than 12 hr.

Growing community of inventors

Avon Lake, OH, United States of America

Victor L Ledesma