Many Maruoka chiral phase-transfer catalysts are based on quaternizing the azepine nitrogen with substituted binapthyl and/or diphenyl groups to get a twisted asymmetric structure. The chiral phase-transfer catalyst described in this patent is atypical in that one of the alkyl groups is a methyl group.

Usually when a methyl group is one of the four alkyl groups that quaternizes a nitrogen, the resulting quat is “accessible” and can make a tight ion pair. In theory, tighter ion pairs can enhance chiral recognition in chiral PTC applications. It is not clear if there is any effect at all of accessibility of the positive charge of the nitrogen in this case since there is so much other steric hindrance on the quat.

Now contact Marc Halpern of PTC Organics Inc. to benefit from the highly specialized expertise in industrial phase-transfer catalysis to improve your choice of phase-transfer catalyst and other PTC process parameters.

Methyl triphenyl phosphonium salts are used in high temperature PTC applications and strong base PTC applications in which other phase-transfer catalysts are not stable enough. US Patent 9,238,606 (Penney, J.; Vetter, A.; Norman, D.; Eastman Chemical Company, 19-Jan-2016) reported the use of two methyl triphenyl phosphonium salts for the carbonylation of methanol to acetaldehyde.

The catalyst system in this patent for the conversion of methanol to acetaldehyde in the presence of carbon monoxide and hydrogen was a mixture of methyl triphenyl phosphonium iodide (MePPh3I), a phosphonium cobalt iodide (MePPh3)2CoI4 and 1,3-bis(diphenylphosphino)propane. The MePPh3I was used usually at about 0.25%-0.35% and the other catalysts about 1/10 of that.

The reaction temperature was 175C to 205C. The phosphonium salts were good this application. Conversions and selectivities were good though not near quantitative but the products could be separated, so it looks like good technology. One of the advantages of this technology is that methyl iodide is not needed as a co-catalyst and the levels of methyl iodide in the system are low, typically less than 100 ppm.

If you need help choosing the best phase-transfer catalyst for a commercial application or for a PTC process in development, now contact Marc Halpern of PTC Organics Inc.

Quaternary ammonium salts adsorb strongly onto polar solid supports such as silica, alumina and clays. This provides the opportunity to perform efficient PTC reactions and benefit from east separation of the phase-transfer catalyst from the product and recycle.

In a patent issued this month (Ichihara, J.; Yamaguchi, S.; Kameyama, A.; Suzuki, T.; Morikita, T.; (JX Nippon Oil & Energy Corporation & Osaka University) US Patent 9,212,188, 15-Dec-2015), tetrahydroindene was epoxidized to the diepoxide using (CetylPy)9(NH4)[H2W12O42] that is a solid catalyst supported on apatite. The epoxidizing agent was 35% H2O2 and a yield of 93% was achieved in 2 hours at 25 deg C.

If your company can benefit from choosing the optimal phase-transfer catalyst, now contact Marc Halpern to integrate PTC Organics’ highly specialized expertise in industrial phase-transfer catalysis with your commercial goals to increase profit, process performance and R&D efficiency.

When a PTC reaction works so well that multiple phase-transfer catalysts work very well (and non-PTC processes give much lower yield or selectivity), then one can use the least expensive phase-transfer catalyst.

In this case of N-mesylation, tetramethyl ammonium chloride worked about as well as TBAB and benzyl triethyl ammonium chloride, so 1/3 the weight of the less expensive TMAC was used instead of the standard TBAB. Less weight plus less cost per weight results in more savings.

It is interesting to note that mono-N-mesylation is achieved in high yield and selectivity. One may speculate that if base would have been used, di-N-mesylation may have been observed since the mono-N-mesylated aniline is more acidic than the non-mesylated aniline.

Your PTC process development program can benefit from expert choice of phase-transfer catalyst for reactivity, selectivity, catalyst separation from the product and catalyst cost. Now contact Marc Halpern of PTC Organics to learn how to optimize choice of phase-transfer catalyst.

Cyclodextrins are cyclic (macrocyclic) oligomers of sugar molecules. Typical cyclodextrins contain  glucose monomers with six units (alpha cyclodextrin), seven units (beta-cyclodextrin) or eight units (gamma-cyclodextrin) in a ring, creating a cone shape. Since cyclodextrins are hydrophobic inside and hydrophilic outside, they can form complexes with hydrophobic compounds on the inside and possibly function as “inverse phase-transfer catalysts” to transfer them into an aqueous phase.

As shown in our book “Phase-Transfer Catalysis: Fundamentals, Applications and Industrial Perspectives”, in chapters written by Charles Starks, beta-cyclodextrins and modified beta-cyclodextrins, have been used in inverse PTC applications for reduction of aryl halides and conjugated dienes, epoxidation of alkenes such as norbornene and styrene, isomerization of allyl anisole and radical polymerization of water-soluble vinyl monomers such as acrylic acid.

If your company can improve process performance, profit and R&D efficiency by choosing the right phase-transfer catalyst, now contact Marc Halpern of PTC Organics to explore a path forward to integrate highly specialized expertise in industrial PTC with your process R&D program.

This month we attended the Specialty and Agrochemicals tradeshow in Charleston, SC and we learned that “coco benzyl quat” (in methanol or isopropanol) is currently available from Nova Star at a price of less than $2/lb (do not rely on this information for pricing). We assume that this quat is coco alkyl benzyl dimethyl ammonium chloride and we do not know the concentration (which may affect the cost per lb of active quat). It is used as a cationic surfactant and corrosion inhibitor. Coco alkyl is a mixture of alkyl groups of which C12 is the one in the largest % composition.

It is possible that “coco benzyl quat” may be a low cost substitute for higher cost phase-transfer catalysts, though we would be extremely cautious to assure that emulsions will not be formed during the reaction and during workup when ionic strength of the aqueous phase drops after multiple water washes.

More information about this quat can be found from the supplier at http://www.novastarlp.com/pdfs/NovaStar%20Core%20Technologies.pdf.

If your company can benefit from unmatched highly specialized expertise in PTC strong base reactions to achieve low-cost high-performance green chemistry, now contact Marc Halpern of PTC Organics to explore a path forward to integrate that expertise with your process R&D program.

Mark Rubino of Vertellus sent us this very interesting article: Brachvogel, R.-C. et al. Self-assembly of dynamic orthoester cryptates. Nat. Commun. 6:7129 doi: 10.1038/ncomms8129 (2015).

The authors innovated a highly effective complexant with affinity for sodium ions between those of 15-crown-5 and 2.2.1 cryptand. This material is an orthoester cryptate in which nine oxygen donors are bound to the metal ion. The orthoester cryptate is stable against water in neutral solution, but susceptible to hydrolysis in the presence of water and acid. This opens up interesting possibilities for creative chemists.

A major reason that this complexant phase-transfer catalyst may be of higher than usual interest to industrial chemists is that it is produced from two relatively inexpensive bulk chemicals, trimethyl orthoacetate and diethylene glycol. Preparation uses trifluoroacetic acid as catalyst and a stoichiometric metal template.

We again express thanks to Mark Rubino for bringing this to our attention.

Imagine a crown ether-like structure with a whole bunch of customizable functional groups hanging off the ring. This can be achieved by synthesizing “cyclopeptoids”. A peptoid is a poly-N-substituted glycine whose side chains are appended to the nitrogen atom of the peptide backbone, rather than to the α-carbons (as they are in amino acids).

The article by Giorgio Della Sala, Brunello Nardone, Francesco De Riccardisa and Irene Izzo, Org. Biomol. Chem., 2013, 11, 726-731 describes the synthesis and characteristics of these compounds. Cyclopeptoids associate strongly with alkali metal cations, sometimes better than classical crown ethers. One can envision interesting possibilities for these compounds as phase-transfer catalysts that can induce selectivity by modifying the steric and electronic environment around reaction centers into which M+X- are brought.

One of the most comprehensive screening of catalysts ever described in a PTC-related patent was reported in Falling, S. (Eastman Chemical) US Patent 6,395,912, 28-May-2002. This patent has 331 examples and most of them use quaternary phosphonium or ammonium iodides with organotin iodides or zinc iodide as Lewis acid catalyst, with no additional solvent, for the isomerization of epoxybutene to dihydrofuran which is an intermediate for the commodity chemical THF. When a lot of profit is at stake, it is worthwhile to invest R&D resources to screen a lot of catalysts.

This patent is an improvement over previous patents for producing DHF by BASF such as US Patent 5,627,291 and more importantly US 5,034,545. The latter used polyethylene glycols and crown ethers as the phase-transfer catalyst and was the subject of a lawsuit between BASF and Eastman (see http://www.ipmall.info/hosted_resources/Markman/pdfFiles/1998.03.24_BASF_CORPORATION_v._EASTMAN_CHEMICAL.pdf).

PTC Organics has highly specialized expertise in choosing phase-transfer catalysts based on nearly four decades of experience in using the fundamentals of PTC to choose the best catalyst, customized for each application.

PTC Organics also works with attorneys in patent cases such as the one cited above to understand the basis for disputes relating to patent claims involving phase-transfer catalysis.

Now contact Marc Halpern of PTC Organics to learn how PTC Organics can help your company improve process performance, protect PTC-related intellectual property and increase profit using phase-transfer catalysis.

Cryptands are like crown ethers in which 2 of the oxygen atoms are replaced by trivalent nitrogen atoms that enable incorporation of another ring in the molecule. Cryptands have extremely high affinity for cations making them stronger complexants than crown ethers. Crown ethers are prohibitive in cost for most industrial applications and cryptands are even more expensive than that. But when you have a high value added need for very strong complexation, cryptands can deliver that performance.

An interesting patent describes the functionalization of cryptands and crown ethers for attachment to electrode surfaces. See US Patent 8,795,924.

If you can benefit from expert help to choose highly effective phase-transfer catalysts for your process development programs, now contact Marc Halpern to explore integrating the highly specialized expertise of PTC Organics in industrial phase-transfer catalysis with your process development goals.