There is growing interest in publications and patents that describe imdiazolium chloroaluminates, pyridinium chloroaluminates and quaternary ammonium chloroaluminates (Q+ AlCl4-) to promote the oligomerization and alkylation of alkenes. The reaction is essentially an acid catalyzed alkylation with some similarities to how gasoline alkylate is made but for higher molecular weight oils (gasoline alkylate is made from isobutane and butene using sulfuric acid or HF as the catalyst).
Of course, inorganic sulfuric acid and HF are not soluble in nonpolar hydrocarbons. So, there is an industry with smart engineers who design contactors to make this reaction work for gasoline alkylate.
Technology has been developed to oligomerize and alkylate higher molecular weight alkenes that seems like phase-transfer catalysis though PTC is not mentioned in the publications or patents. The pyridinium or quaternary ammonium chloroaluminates are referred to as ionic liquid solvents for the alkylation or oligomerization or ionic liquid catalysts and indeed are used in catalytic quantities.
Maybe we are just dealing with semantics, but the essence of the technology is to bring the reactants and catalyst together in an organic phase where the reaction takes place. When using catalytic amounts of [Q+ AlCl4-] to solubilize both the inorganic Lewis acid and the alkene in the same phase, it sure sounds like PTC to me.
Examples can be found in US Patent 8,198,500, that uses methyl tributyl ammonium chloroaluminate and butyl pyridinium chloroaluminate. Another interesting article on this topic is A.S. Berenblyum et al. , Applied Catalysis A: General 315 (2006) 128–134
Methyl tributyl ammonium chloroaluminate is made from AlCl3 and methyl tributyl ammonium chloride.
About Marc Halpern
Dr. Halpern is founder and president of PTC Organics, Inc., the only company dedicated exclusively to developing low-cost high-performance green chemistry processes for the manufacture of organic chemicals using Phase Transfer Catalysis. Dr. Halpern has innovated PTC breakthroughs for pharmaceuticals, agrochemicals, petrochemicals, monomers, polymers, flavors & fragrances, dyes & pigments and solvents. Dr. Halpern has provided PTC services on-site at more than 260 industrial process R&D departments in 37 countries and has helped chemical companies save > $200 million. Dr. Halpern co-authored five books including the best-selling “Phase-Transfer Catalysis: Fundamentals, Applications and Industrial Perspectives” and has presented the 2-day course “Practical Phase-Transfer Catalysis” at 50 locations in the US, Europe and Asia.
Dr. Halpern founded the journal “Industrial Phase-Transfer Catalysis” and “The PTC Tip of the Month” enjoyed by 2,100 qualified subscribers, now beyond 130 issues. In 2014, Dr. Halpern is celebrating his 30th year in the chemical industry, including serving as a process chemist at Dow Chemical, a supervisor of process chemistry at ICI, Director of R&D at Sybron Chemicals and founder and president of PTC Organics Inc. (15 years) and PTC Communications Inc. (20 years). Dr. Halpern also co-founded PTC Interface Inc. in 1989 and PTC Value Recovery Inc. in 1999. His academic breakthroughs include the PTC pKa Guidelines, the q-value for quat accessibility and he has achieved industrial PTC breakthroughs for a dozen strong base reactions as well as esterifications, transesterifications, epoxidations and chloromethylations plus contributed to more than 100 other industrial PTC process development projects.
Dr. Halpern has dedicated his adult life to his family and to phase-transfer catalysis (in that order!).
