Epichlorohydrin, III

Effect of dimer formation on deactivation. Another possible mode of deactivation is formation of inactive Co dimers or oligomers. To test for these species, we examined the ESI-mass spectram of fresh and deactivated Co-salen catalysts in dichloromethane solvent (22). The major peak in the mass spectram occurred at m/z of 603.5 for both Jacobsen s Co(II) and Co(III)-OAc salen catalysts, whereas much smaller peaks were observed in the m/z range of 1207 to 1251. The major feature at 603.5 corresponds to the parent peak of Jacobsen s Co(II) salen catalyst (formula weight = 603.76) and the minor peaks (1207 to 1251) are attributed to dimers in the solution or formed in the ESI-MS. The ESI-MS spectrum of the deactivated Co-salen catalyst, which was recovered after 12 h HKR reaction with epichlorohydrin, was similar to that of Co(II) and Co(III)-OAc salen. Evidently, only a small amount of dimer species was formed during the HKR reaction. However, the mass spectram of a fresh Co(III)-OAc salen catalyst diluted in dichloromethane for 24 h showed substantial formation of dimer. The activity and selectivity of HKR of epichlorohydrin with the dimerized catalyst recovered after 24 h exposure to dichloromethane were similar to those observed with a fresh Co-OAc salen catalyst. Therefore, we concluded that catalyst dimerization cannot account for the observed deactivation. 

This hypothesis was tested by carrying out a kinetic study of the HKR of epichlorohydrin using Jacobsen Co(III)-salen catalyst with four different counterions, namely, acetate (OAc), tosylate (OTs), chloride (Cl) and iodide (I) (22). Approximately, 0.5 mol% loading of all the catalysts was used to perform the HKR of epichlorohydrin. As shown in Table 43.2, the ran initial rates with Co-OAc and Co-OTs salen catalysts were similar and slightly below those with Co-Cl and Co-I salen. Nevertheless, all of the catalysts were quite active initially. After conducting... 

Kim et al. [61] demonstrated that with the change in counter ion in Co(III)-X where (X= 9-17), the catalysts could be reused ten times after simple distillation of products without observable loss in activity and enantioselectivity for HKR of epichlorohydrin. Interestingly the catalyst-regeneration step was not required with the use of PFe 11 and BF4 12 as counter ion in this system (Scheme 4). 

Figure 3 Immobilized Co (II) salen complexes are oxidized to Co (III) and utilized in the hydrolytic kinetic resolution of rac-epichlorohydrin.

Figure 4 Kinetic plot of the ffKR of rac-epichlorohydrin using the homogeneous and poly(styrene) supported Co(III) salen catalysts.

Phenolic, (I), and naphtholic, (II), condensation polymers containing cyclopentane were previously prepared by Sue et al. (1). These materials were subsequently epoxidized with epichlorohydrin and used in electronic devices as ICs and Lumen solubility indexes (LSIs). In a subsequent investigation by Abe et al. (2) novolak resins functionalized with thiophene, (III), were prepared and used as adhesives. 

Figure 4. Volume change of elastomers as a function of MTBE concentration in Indolene HO-III. Key o.fluorocarbon , epichlorohydrin homopolymer a, chlorosulfonated polyethylene and o, EPDM.

The hydrolytic kinetic resolution (HKR) of racemic terminal epoxides catalyzed by chiral (salen)-Co(III) complexes provides efficient access to epoxides and 1,2-diols, valuable chiral building blocks, in highly enantioenriched forms. While the original procedure has proved scalable for many substrates, several issues needed to be overcome for the process to be industrially practical for one of the most useful epoxides, epichlorohydrin. Combined with kinetic modelling of the HKR of epichlorohydrin, novel solutions were developed which resulted in linearly scalable processes that successfully addressed issues of catalyst activation, analysis and reactivity, control of exothermicity, product isolation, racemization, and side-product formation. 

The HKR reaction is catalyzed by Co(III) complexes of the well-known Jacobsen salen ligand formed by the condensation of two equivalents of 3,5-di-tert-butylsali-cylaldehyde with either enantiomer of trans-1,2-diaminocyclohexane [6]. These catalysts show remarkable levels of selectivity and reactivity, and they can be indefinitely recycled with most substrates (epichlorohydrin being a notable exception). The counterion can be varied to enhance the reactivity of the catalyst with slow-re-acting substrates, but the initially reported acetate complex (X=OAc in Fig. 1) has proved to be the most broadly applicable catalyst [2],... 

Chloride exchange reactions between species were demonstrated by combining racemic epichlorohydrin, racemic CPD, and (S,S)-(salen)-Co(III)-OAc in the ab-... 

With (S,S)-(salen)-Co(III)-OAc, the hydrolysis of (S)-epichlorohydrin exhibited a second order dependence on catalyst concentration, which is consistent with previous results obtained for HKR reactions [1, 10], Significantly, hydrolysis of the slow reacting (R)-enantiomer was estimated to have a zero order dependence on catalyst concentration. Zero order dependence was also observed for the impurity... 

FERMC(III) SULFATE (10028-22-5) Fej(S04)3 Light sensitive. Hygroscopic hydrolyzed slowly in water , forming acid solution and precipitates hydroxide and phosphate salts. Violent reaction with strong bases. Aqueous solution (often shipped as 73% solution) is incompatible with sulfiiric acid, aluminum, caustics, alkylene oxides, ammonia, aliphatic amines, alkanolamines, amides, epichlorohydrin, organic anhydrides, isocyanates, magnesium, methyl isocyanoacetate, vinyl acetate. Corrosive to copper, copper alloys, and both mild and galvanized steel. 

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