Polymer resins from epichlorohydrin
Epichlorohydrin has been shown to be a general sidearm precursor for several lariat ether compounds 1992CSR39. It has recently been used to form macrocycles through the reaction of oxirane fragments (see Figure 19). Thus, epichlorohydrin is treated with BF3 Et2O to give oligomeric dichlorides. This in turn is treated with triethanolamine to form a 13-crown-4 derivative containing a single nitrogen. Macrocycles are included in the network used to complex metal ions such as Ag+ and Au3+. When 1-chloro-2,3-epithiopropane replaces epichlorohydrin in the initial step, a macrocycle containing O, S, and N is formed. Selective binding analysis of oxygen- and sulfur-containing resins in the presence of other metals
Epichlorohydrin (ECH) is another versatile chemical intermediate epichlorohydrin used in a wide variety of applications including epoxy resins, textiles, paper products, inks, dyes, automotive and aircraft parts, biocides, personal care products and ion exchange resins . Historically, ECH has been produced through a three-step process, starting with the chlorination of propylene to produce allyl chloride [Figure 42(a)]. The main by-products of the first reaction are cis and trans 1,3-dichloropropene and 1,2-dichloropropane. The following chlorohydrination of allyl chlorides yields a mixture of dichlorohydrins (also known as glycerol dichlorohydrins) [Figure 42(b)]. 1,2,3-Trichloropropane is a by-product of this reaction. In the third step, ECH is produced by alkaline dehydrochlorination of dichloropropanol isomers [Figure 42(c)]. The traditional manufacture of epichlorohydrin is a corrosive process that causes significant downtime.
Production of glycerol from epichlorohydrin involves: Low-pressure ECH at atmospheric pressure using 10–15% aqueous NaOH [Fig. 42(d)] or Na2CO3 [Fig. Alkaline hydrolysis or high pressure produces a dilute solution of crude glycerol. Soda ash was the preferred alkali, produced from brine and limestone (Solvay Process, 1860s). The glycerol solution undergoes an evaporative crystallization process to concentrate the diluted crude glycerol and precipitate most of the sodium chloride salt.
The use of propylene to produce synthetic glycerol has largely been abandoned due to fundamental changes in glycerin supply caused by the emerging biofuel market. Instead, glycerol was converted from biodiesel produced via dichlorohydrin to bioepichlorohydrin as a new export of glycerol 375 [Epicerol® Process (Solvay), GTE Process (DOW)] (Figure 43). The process proceeds in two reaction steps. In the first step, refined glycerol is hydrochlorinated to 1,3-DCH (1,3-dichloropropanol, 1,3-dichloropropan-2 -alcohol) and 2,3-DCH (2,3-dichloropropanol, 2,3-dichloropropan-1-ol), using a carboxylic acid catalyst such as acetic acid, propionic acid, adipic acid or oxalic acid. In the second step, the mixture of dichlorohydrins is converted to epichlorohydrin by alkaline dehydrochlorination. 376 Compared to conventional ECH production, the new manufacturing process represents a major advance in sustainable manufacturing, especially in reducing chlorinated by-products, water, and chlorine consumption