Epichlorohydrin hydrolysis

A high conversion to glycidyl 2-ethylhexanoate was ultimately achieved by this technique (>99%) although by this time the epichlorohydrin hydrolysis (24.3%) was considered to be too high for this method to be used commercially. 

In an attempt to reduce the overall epichlorohydrin hydrolysis the effect of removal of this component from the reaction system was investigated. A sample of the above reaction mixture was removed after the initial treatment with sodium hydroxide/sodium carbonate solution and the excess epichlorohydrin and toluene removed by vacuum distillation. 

Accordingly, sodium hydroxide (17% aqueous solution) was stirred with the chlorohydrin ester masterbatch prepared above. The reaction was followed at 40 C using a molar ratio of sodium hydroxide to chlorohydrin ester of 2 1. The reaction was followed by gas chromatography. Fig. 18 shows the rates of conversion of epichlorohydrin and chlorohydrin ester during the reaction. Again, it was shown that after 6.5 hours all the sodium hydroxide had been consumed (cf. sodium hydroxide/sodium carbonate reaction at 40 C) at which time only 64% conversion to the epoxy compound was observed. Correspondingly the epichlorohydrin hydrolysis (25%) had increased in comparison to the sodium hydroxide/sodium carbonate method (15.6% at 40 C). 

In order to continue the comparison of the aqueous sodium hydroxide dehydrochlorination with the aqueous sodium hydroxide/ sodium carbonate method the organic phase from the above reaction was removed and retreated with aqueous sodium hydroxide (a further 2 molar excess). Ultimately a 98% conversion to glycidyl 2-ethylhexanoate was achieved but by this time very extensive epichlorohydrin hydrolysis had occurred (56%). It was also found difficult to separate the organic phase from this reaction due to emulsification with the aqueous phase in order to carry out the final purification stage by distillation. 

Modifications to the above techniques may be envisaged for process improvement. In the above reactions epichlorohydrin is present in excess after the initial formation of the chlorohydrin ester (4 molar excess) as a consequence of the requirements of the stage I reaction. However it has been shown that epichlorohydrin hydrolysis competes with the required reaction in stage II of the process. It would therefore be desirable to reduce the concentration of epichlorohydrin prior to ring closure. It has however been shown that epichlorohydrin is required to effect ring closure (transepoxidation) and work is in hand to optimise the concentration of this component during the dehydrochlorination reaction. 

Fig. 18 Kinetic parameter estimation A (R)-epichlorohydrin hydrolysis, x (S)-epi-chlorohydrin hydrolysis, O impurity formation.

Degradation of epichlorohydrin (l-chloro-2,3-epoxypropane) may proceed by hydrolysis of the epoxide to 3-chloro-l,2-propanediol that is then converted successively into... 

The degradation of 1,2,3-trichloropropane by Agrobacterium radiobacter strain ADI involves hydrolysis of an intermediate epichlorohydrin (3-chloroprop-l-ene) to the diol (Bosma et al. 1999, 2002). An enzyme from this strain has been modified from the use of epichlorohydrin that is its normal substrate to accept dy-l,2-dichloroethene with the release of chloride and the presumptive formation of glyoxal (Rui et al. 2004). 

Kim et al. (19) also observed that the ee of recovered epichlorohydrin was reduced to 17% in the second hydrolysis reaction with Jacobsen s Co-OAc salen catalyst, if the catalyst was not regenerated with acetic acid in air. Although they attributed the loss of enantioselectivity to the reduction of Co(lll) to Co(ll) salen complex after the HKR reaction, no spectroscopic evidence was provided. Therefore, we probed the catalyst by UV-Vis and XANES spectroscopy before and after the HKR reaction. 

The original preparation of y-crotonolactone by Lespieau involved a five-step sequence from epichlorohydrin and sodium cyanide. A recent detailed study of this procedure reported an overall yield of 25% for the lactone. Glattfeld used a shorter route from glycerol chlorohydrin and sodium cyanide hydrolysis and distillation of the intermediate dihydroxy acid yielded y-cro-tonolactone in 23% yield and -hydroxy-y-butyrolactone in 28% yield. The formation of y-crotonolactone in 15% yield has also been reported from pyrolysis of 2,5-diacetoxy-2,5-dihydrofuran at 480-500 . ... 

Chemical/Physical. The hydrolysis rate constant for 1,2,3-trichloropropane at pH 7 and 25 °C was determined to be 1.8 x lO Vh, resulting in a half-life of 43.9 yr (Ellington et ah, 1988). The hydrolysis half-lives decrease at varying pHs and temperature. At 87 °C, the hydrolysis half-lives at pH values of 3.07, 7.12, and 9.71 were 21.1, 11.6, and 0.03 d, respectively (Ellington et al, 1986). By analogy to l,2-dibromo-2-chloropropane, the following hydrolysis products would be formed 2,3-dichloro-l-propanol, 2,3-dichloropropene, epichlorohydrin, l-chloro-2,3-... 

Approximately 27% of glycerol (glycerin) comes from a synthetic process, the hydrolysis of epichlorohydrin. The remaining 73% is made from fats as a by-product of soap manufacture. 

The reaction actually involves the sodium salt of bisphenol A since polymerization is carried out in the presence of an equivalent of sodium hydroxide. Reaction temperatures are in the range 50-95°C. Side reactions (hydrolysis of epichlorohydrin, reaction of epichlorohydrin with hydroxyl groups of polymer or impurities) as well as the stoichiometric ratio need to be controlled to produce a prepolymer with two epoxide end groups. Either liquid or solid prepolymers are produced by control of molecular weight typical values of n are less than 1 for liquid prepolymers and in the range 2-30 for solid prepolymers. 

Reaction of olefin oxides (epoxides) to produce poly(oxyalkylene) ether derivatives is the etherification of polyols of greatest commercial importance. Epoxides used include ethylene oxide, propylene oxide, and epichlorohydrin. The products of oxyalkylation have the same number of hydroxyl groups per mole as the starting polyol. Examples include the poly(oxypropylene) ethers of sorbitol (130) andlactitol (131), usually formed in the presence of an alkaline catalyst such as potassium hydroxide. Reaction of epichlorohydrin and isosorbide leads to the bisglycidyl ether (132). A polysubstituted carboxyethyl ether of mannitol has been obtained by the interaction of mannitol with acrylonitrile followed by hydrolysis of the intermediate cyanoethyl ether (133). 

There are four processes for industrial production of allyl alcohol. One is alkaline hydrolysis of allyl chloride. A second process has two steps. The first step is oxidation of propylene to acrolein and the second step is reduction of acrolein to allyl alcohol by a hydrogen transfer reaction, using isopropyl alcohol. At present, neither of these two processes is being used industrially. Another process is isomerization of propylene oxide. Until 1984. all allyl alcohol manufacturers were using this process. Since 1985 Showa Denko K.K. has produced allyl alcohol industrially by a new process which they developed- This process, which was developed partly for the purpose of producing epichlorohydrin via allyl alcohol as the intermediate, has the potential to be the main process for production of allyl alcohol. The reaction scheme is as follows ... 

To validate IR imaging for screening reactions, the activity and enantioselectivity of metal catalysts (S,S)-4a-c for the hydrolysis of epichlorohydrin was tested. Time-resolved changes in temperature indicated that the (S,S)-4c catalyst as the most active and an S-configured epoxide (lc) is preferred for hydrolysis (Figure 3.45). 

Figure 3.45 Infrared-thermographic picture of the time-dependent activity of selected catalysts for the hydrolysis of epichlorohydrin after 0, 2.5, 4, 5, 7, 8, 15 and 32 min from (a) to (i), with (e) and (f) recorded at the same time but different scales [75].

Figure 10-14 Hydrolysis products formed from epichlorohydrin.

Milkovich et al.18 reacted living polystyrene with epichlorohydrin and, after hydrolysis of the epoxide ring, obtained quantitatively a macromonomer possessing at one chain end two adjacent hydroxy groups which can subsequently add to diisocyanates to yield graft polycondensates ... 

Glycerin by the Epichlorohydrin Process. In the ECH process, synthetic glycerin is produced in three successive operations, the end products of which are allyl chloride, ECH, and finished glycerin, respectively. Glycerin is formed by the hydrolysis of ECH with 10 percent caustic. Crude glycerin is separated from this reaction mass by multiple-effect evaporation to remove salt and most of the water. A final vacuum distillation yields a 99+ percent product. 

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