Chlorination of propylene

This derivative, abbreviated AC, is a transparent, mobHe, and irritative Hquid. It can be easHy synthesized from aHyl alcohol and hydrogen chloride (23). However, it is iadustriaHy produced by chlorination of propylene at high temperature. 

High temperature chlorination of propylene yields aHyl chloride, which is used in glycerol (qv) production (110) ... 

The dkect high temperature chlorination of propylene continues to be the primary route for the commercial production of aHyl chloride. The reaction results in aHyl chloride selectivities of 75—80% from propylene and about 75% from chlorine. Additionally, a significant by-product of this reaction, 1,3-dichloropropene, finds commercial use as an effective nematocide when used in soil fumigation. Overall efficiency of propylene and chlorine use thus is significantly increased. Remaining by-products include 1,2-dichloropropane, 2-chloropropene, and 2-chloropropane. 

Reaction Mechanism. High temperature vapor-phase chlorination of propylene [115-07-17 is a free-radical mechanism in which substitution of an allyhc hydrogen is favored over addition of chlorine to the double bond. Abstraction of allyhc hydrogen is especially favored since the allyl radical intermediate is stabilized by resonance between two symmetrical stmctures, both of which lead to allyl chloride. 

The production of allyl chloride could be effected by direct chlorination of propylene at high temperatures (approximately 500°C and one atmosphere). The reaction substitutes an allylic hydrogen with a chlorine atom. Hydrogen chloride is a by-product from this reaction ... 

Glycerol. Another synthetic product that is derived from propylene for the production of resins is glycerol. Synthetic production of this material, which started in 1948 at the Houston, Tex., plant of Shell Development Co., culminated a long research program by E. C. Williams and coworkers (45) in which the process was developed through a complex series of reactions starting with the chlorination of propylene (7). The Houston plant has a reported capacity of 36,000,000 pounds per year, which is equivalent to 20% of the prewar production of glycerol (8). 

Commerciol Dichlorohydrin consists of the above two isomers, the proportions of which depend on method of prepn d 1.36-1.39, bp 175-80°, flash p 74°, Glycerol was the main source for the prepn of glycerol chloro-hydrins until the process for direct substitutive chlorination of propylene to allyl chloride paved the way for synthesis by chlorohydrination of allyl chloride. In the synthesis from glycerol, excess HCI is used in the presence of 4% acetic acid. The reaction is run at 130° to yield 90% of product which is mainly the a,y-form. Synthesis from propylene yields a mixt of approx 70% a,/8-form 8c 30% a,y-form. Addn of HCI to epichlorohydrin, CH2 CHCH> Cl, at... 

Chlorination of propylene oxide and epichlorohydrin has been conducted in the presence of sunlight or a suitable substitute, but the course of the reactions remains obscure. Propylene oxide is reported to give a complex mixture of products, two of which are l,3-dichloro-2-propanol and chloroaoetone Epichlorohydrin (Eq. 949) appears to form 1,1 -dichloro- 2,3-epoxypropane initially, and then to react further, giving finally 1,1,2,3,3-pentachloro-2,3-epoxypropane. 10... 

Allyl Chloride (3-chioropropene-1). [CAS 107-05-1]. Ally I chloride can be synthesized by reaction of allyl alcohol with HCI or by treatment of allyl formate with HCI in the presence of a catalyst (ZnCLV Commercial production is by chlorination of propylene at high temperatures, about 500°C. using a large excess of propylene. It is used in the synthesis of... 

Addition of chlorine atoms to ethylene and chloroethylenes has been extensively investigated. Some work has also been done on termal chlorination of propylene and butene at higher temperatures. The references and the elementary reactions postulated have been listed by Steacie (97). The mechanism generally assumed is the well known chain chlorination mechanism. When the initiation is photochemical, this comprises the following reactions... 

To illustrate the use of the algorithm, a case of allyl chloride manufacturing was used. Allyl chloride is manufactured by means of non-catalytic chlorination of propylene. Consider the following reaction system. 

The numerical example is the chlorination of propylene. There are two vapor-phase, irreversible, exothermic reactions ... 

Most perchloroethylene has been coproduced with carbon tetrachloride by the chlorination of propylene and/or chloropropanes. After the phaseout of CFC-11 and -12, the market for carbon tetrachloride disappeared. Producers have modified their units to shift the production to perchloroethylene. 

The key reaction in this manufacturing process is the hot chlorination of propylene, which fairly selectively gives substitution to methyl group rather than the addition to the double bond. In this chlorination step, fresh propylene is first mixed with recycle propylene. This mixture is dried over a desiccant, heated to 650-700°F, and then mixed with chlorine (C3H6 to Cl2 ratio is 4 1) and fed to a simple steel tube adiabatic reactor. The effluent gases (950°F) are cooled quickly to 120°F and fractionated. The yield of allyl chloride is 80-85 percent. 

Allyl Alcohol and Glycerol. These two products are treated together since both involve the chlorination of propylene to allyl chloride. The Shell allyl alcohol process is described by Fairbairn, Cheney, and Cherniavsky (30). This same process and the glycerol process are described by Williams (125). The German counterpart of these... 

Table 5-6 Conversion vs reactor length for chlorination of propylene NON ADIABATIC OPERATION...

AUyl Chloride High-temperature Chlorination of Propylene Allyl chloride is manufactured by the noncatalytic chlorination of propylene... 

The chief secondary reaction is the further chlorination of allyl chloride to 1,3-dichloropropane. Another side reaction is the additive chlorination of propylenes to 1,2-dichloropropane. This reaction is favored by low temperatures and, at a reaction temperature of 200 C or lower, takes place to the virtual exclusion of substitutive reactions. Dichloropropane is always present to an appreciable extent even with reaction temperatures as high as 600 C. 

Epichlorohydrin, 6—CihCH—CH2CI, can be obtained by the oxidation of allyl chloride with peracids, by the high-temperature chlorination of propylene with subsequent addition of chlorine/water and elimination of hydrogen chloride, or by a three-stage process starting with acrolein. Elastomers resistant to oil, ozone, and cold can be obtained from the homopolymerization of epichlorohydrin with, for example, Et3Al/H20/acetyl acetone as initiator ... 

Epichlorohydrin (l-chloro-2,3-epoxy propane), is obtained by the chlorination of propylene, followed by the reaction of allyl chloride with hypochlo-rous acid. The resultant product is treated with Ca(OH)2 and is a colourless liquid with a density of 1.18 g cm mp -57°C and bp 115°C. It is a colorless liquid with a pungent garlic-like odour, moderately soluble in water but miscible with most polar organic solvents. Its principal use is as a reactant in the manufacture of diglycedyl ether-based epoxy resin. 

CH—CH2—O, can be produced by the chlorination of acrolein, the high-temperature chlorination of propylene, or directly from allyl chloride ... 

Propylene oxide, made by reacting propylene with chlorine to form propylene chloro-hydrin which is then dehydrochlorinated with caustic soda or lime (Eqs. 3-5), is used in the production of polyether polyols used for producing urethane foam. It also finds use in propylene glycol for making unsaturated polyester resins and in the pharmaceutical and food industries. Epichlorohydrin (EPI), formed by chlorination of propylene to allyl chloride and then dehydrochlorination (Eqs. 6 and 7), is used to make epoxy resins for producing laminates, fiber-reinforced composites, protective coatings, and adhesives. 

Ethylene oxide is manufactured hy direct oxidation of ethylene, in contrast PO is only obtained in coproduct processes. The classical process, chlorination of propylene, is still used by Dow, one of the world s largest producer of polyether polyols. In contrast, all other producers use the Halcon process, based on the simultaneous production of PO and styrene monomer or t-butyl alcohol. In view of the demise of AITBE (methyl-f-butyl ether based on t-butyl alcohol) as a fuel additive, the styrene coproduct process (POSM) will remain as the economically viable route to PO. A recent example is the new (SMPO) plant of Basell at Moerdijk in the Netherlands. The largest producer of PO, the former Arco (now Lyondell), has sold its global polyol business to Bayer in 1999. Lyondell will also provide Bayer a long-term, low cost supply of PO. Recently, Dow annoimced that it also will use the POSM route to PO in a new facility. 

Glycerol is the polyhydric alcohol most widely used for the preparation of alkyd resins and is obtained both synthetically and as a by-product in the manufacture of soap. The principal methods for the synthesis of glycerol are based on either the chlorination or oxidation of propylene. In the former methods, the first step is the hot chlorination of propylene to give allyl chloride ... 

Propylene oxide, 1,2-epoxy-propane, PO, is a very reactive substance and one of the most important chemical intermediates.The worldwide propylene oxide capacity was estimated to 4.9 million t/y in 1996, the increase is ca. 4%/y. After the PVC production, the chlorination of propylene is the second largest single chlorine consumer. 

Allyl chloride is produced by the thermal chlorination of propylene at elevated temperatures and relatively low pressures. Along with the main reaction, several side reactions also take place. These are shown below. 

Epichlorohydrin is necessary for both the homopolymer as well as the copolymer. It is produced from the chlorination of propylene as shown in Eigure 4.35. 

Epichlorohydrin, or l-chloro-2,3-epoxypro-pane, is a key raw material in the manufacture of epoxy resins. Epichlorohydrin is made by chlorination of propylene, treatment with hypochlorous acid, and dehydrohalogenation of the intermediate to give the mono-epoxide. 

Allyl chloride is produced by direct chlorination of propylene further reaction with chlorine and water, by chlorohydrination and hydrolysis, yields epichlorhy-drin. 

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