Epichlorohydrin, activation

Hydroxyl Group Derivatization. Epichlorohydrin Activation. One-half gram of N-acetylated heparin was dissolved in 10 mL of 1.0M Na2C03 solution. One milliliter of epichlorohydrin and either 1 mL of n-butylamine or 1 g of glycine or 2-aminoethyl hydrogen sulfate were added to the heparin solutions and allowed to react at 40°C for 5 h. Reaction schemes are illustrated in Figure 2. The hydroxyl-derivatized heparins were then dialyzed and freeze-dried. 

Cellulose activated with epichlorohydrin has been treated with glycine and then coupled with a-amylase via a carbodi-imide mediator. Glucoamylase was also immobilized by a carbodi-imide-mediated reaction with epichlorohydrin-activated cellulose, which had previously been treated with 6-aminohexanoic acid, or by reaction with diazotized benzidine previously coupled to epichloro-hydrin-activated cellulose. Immobilized 4-chloromercuribenzoate was prepared by reaction with 1,6-diaminohexane coupled to epichlorohydrin-activated cellulose, and used for the affinity chromatographic purification of a-amylase and glucoamylase. 

Reaction with epichlorohydrin-activated agarose Reaction with dextran cyclic imidocarbonate... 

Carbodi-imide-mediated reaction with epichlorohydrin-activated agarose previously treated with glycine Reaction with a syw-trichlorotriazine-activated polystyrene anion exchanger reaction with 1,4-benzoqumone-activated aminopropyl silica reaction with an N-hydroxysuccinimide ester derivative of 3-succinimidopropyl silica Carbodi-imide- or 2,4-toluenedi-isocyanate-mediated reaction with amino-or carboxy-aerosU... 

Carbodi-imide-mediated reaction with epichlorohydrin-activated agarose previously treated with glycine... 

The immobilization of a-amylase and glucoamylase on epichlorohydrin-activated cellulose has been investigated. ... 

Specialty Epoxy Resins. In addition to bisphenol, other polyols such as aUphatic glycols and novolaks are used to produce specialty resins. Epoxy resins may also include compounds based on aUphatic, cycloaUphatic, aromatic, and heterocycHc backbones. Glycidylation of active hydrogen-containing stmctures with epichlorohydrin and epoxidation of olefins with peracetic acid remain the important commercial procedures for introducing the oxirane group into various precursors of epoxy resins. 

Reaction of pyroc techol with epichlorohydrin in the presence of base affords the benzodioxan derivative, 136, (The reaction may well involve initial displacement of halogen by phenoxide followed by opening of the oxirane by the anion from the second phenolic group.) Treatment of the alcohol with thio-nyl chloride gives the corresponding chloro compound (137). Displacement of halogen by means of diethylamine affords piper-oxan (138), a compound with a-sympathetic blocking activity. 

Substitution of an additional nitrogen atom onto the three-carbon side chain also serves to suppress tranquilizing activity at the expense of antispasmodic activity. Reaction of phenothia zine with epichlorohydrin by means of sodium hydride gives the epoxide 121. It should be noted that, even if initial attack in this reaction is on the epoxide, the alkoxide ion that would result from this nucleophilic addition can readily displace the adjacent chlorine to give the observed product. Opening of the oxirane with dimethylamine proceeds at the terminal position to afford the amino alcohol, 122. The amino alcohol is then converted to the halide (123). A displacement reaction with dimethylamine gives aminopromazine (124). ... 

Insertion of a longer spacer is compatible with antifungal activity. Reaction of epichlorohydrin with 4-chlorobenzyl-magnesium chloride leads to substituted phenylbutane Dis-... 

Some laboratory studies with rats and mice have linked trichloroethylene exposure to various types of cancers. Several of these studies, however, should be viewed cautiously, since the tumorigenic activity might be influenced by the presence of direct-acting compounds, namely the epoxides (e.g., epichlorohydrin) added as stabilizers in trichloroethylene. Epoxides are known to be very reactive, and some, such as epichlorohydrin, are potent carcinogens themselves. 

We monitored the percent conversion of epichlorohydrin and enantiomeric excess of the recovered S-epichlorohydrin with time by using GC-FID. Approximately 54% conversion and >99% ee were obtained in about 4 h reaction time. After 4 h, the epichlorohydrin was removed under vacuum at room temperature and diol was removed at a temperature of 329 K. The recovered catalyst was further treated in the HKR of racemic mixture of fresh epichlorohydrin. In the second run, we observed a decrease in the conversion and ee compared to the fresh catalyst. The Co-salen was again recovered after the second run by removing all the products under vacuum and recycled two more times. With each subsequent HKR reaction, the conversion and ee were found to decrease with time (22). Table 43.1 summarizes the initial rates and ee s determined from the four runs without intermediate catalyst regeneration. Interestingly, the initial catalyst activity was resumed when the catalyst was regenerated with acetic acid prior to recycle. 

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... 

Figure 25.9 Epichlorohydrin can be used to activate the hydroxyl group of mPEG, creating an epoxy derivative. Reaction with amine-containing molecules yields secondary amine bonds.

Alkylations of phenols with epichlorohydrin under PTC conditions and microwave irradiation were described twice in 1998. Subsequently, ring-opening reactions of the epoxide group were also performed using microwaves (Eqs. 20 and 21) [31, 32]. In the first catalytic synthesis of chiral glycerol sulfide ethers was described [31] in the second biologically active amino ethers were prepared [32],... 

Thioureas mainly find use for the vulcanisation of CR, epichlorohydrin (ECO) and some ethylene propylene diene terpolymer (EPDM) compounds. They show high crosslinking activity, with usually adequate compound flow time before onset of the crosslinking. In EPDMs, the thioureas are used as activators for low activity third monomer types and, in the presence of calcium oxide desiccants, in free state vulcanisation of extrudates, etc. The use of thioureas can overcome the retardation caused by the desiccant. In this case some care must be taken otherwise overcompensation may occur. Thioureas are not used in food product applications and are a known health hazard, particularly for pregnant women. 

Widespread chlorine-containing polymers would include, 1) stable molding material for practical use such as polyvinyl chloride (PVC), polyvinylidene chloride and poly(epichlorohydrin)(PECH) and, 2) reactive polymers capable to introduce additional functional groups via their active chlorines such as chloromethyl polystyrene, poly (3-chloroethyl vinyl-ether) and poly (vinyl chloroacetate). While the latter, especially the chloromethyl polystyrene, has been widely used recently for the synthesis of variety of functional polymers, we should like to talk in this article about the chemical modification of the former, mainly of PVC and PECH, which was developed in our laboratory. 

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