The reaction described here appears to be a PTC reaction in which the quaternary ammonium phase-transfer catalyst transfers hydrazine into the organic phase by hydrogen bonding between the chloride of the quat salt and the N-H of the hydrazine. Once transferred into the nonpolar toluene phase from the hydrazine hydrate phase that contains additional water from the 75% methyl tributyl ammonium chloride in water, the non-hydrated reacts with the epoxide ring with enhanced reactivity and the reaction is 98.5% complete after 5 hours.
At the end of the reaction, the aqueous phase is separated from the organic phase and the majority of the unreacted hydrazine and nearly all of the phase-transfer catalyst is located in the aqueous phase which is then recycled achieving a very high atomic efficiency.
In another example, solid methyl tributyl ammonium chloride was used. Apparently, since there was less water, only 16 mole% quat chloride was needed, presumably since this hydrophilic quat chloride doesn’t have as much opportunity to reside in the aqueous phase and be less active and less available.
In addition, when using solid methyl tributyl ammonium chloride, the inventors were able to reduce the hydrazine hydrate usage from 4.8 equivalents to 1.52 equivalents and still achieved 88% yield. By reducing the excess hydrazine hydrate by 86%, there is a lot less economic driving force to recycle the excess hydrazine hydrate. The advantage of being able to recycle the methyl tributyl ammonium chloride was still significant and the inventors could choose which economic benefit is more valuable. The process development team at Adama Makhteshim has more expertise in PTC than most other companies and that expertise is evident in this patent application.
In fact, the inventors note that the yield shown for the reaction conditions shown in the diagram is much higher than previous technology from 2001 which achieved only 47% yield.
By the way, methyl tributyl ammonium chloride is referred to in the patent as Aliquat (R) 175 9trademark of BASF). This is the name that I convinced Henkel to use in 1996 (later Cognis, later BASF) and I named it after the q-value that I invented in 1988. Methyl tributyl ammonium has a q-value of 1.75. BASF stopped promoting Aliquat 175 as a phase-transfer catalyst many years ago when they abandoned phase-transfer catalysts as a strategic business. I helped Henkel and Cognis build their PTC business from 1996 to 2000 and again from 2004 to 2008. It has been 16 years since we served the PTC community together. The effective PTC salespeople for Cognis now work for other PTC suppliers. Markets change and corporate goals change. We adjust. I remain dedicated to industrial phase-transfer catalysis as I have since 1984 (yes, 40 years!).
