2- Chloropropanal

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. 

As shown, ia the case of chlotination of aEyl chloride, the resonance states of the chloroaEyl radical iatermediates are not symmetrical and their propagation reactions lead to the two different dichloropropene isomers ia an approximate 10 90 ratio (26). In addition, similar reactions result ia further substitution and addition with products such as trichloropropanes, trichloropropenes, tetrachloropropanes, etc ia diminisbing amounts. Propylene dimerization products such as 1,5-hexadiene, benzene, 1-chloropropane, 2-chloropropane, high boiling tars, and coke are also produced ia smaE amounts. 

Product Recovery. The aHyl chloride product is recovered through the use of several fractional distillation steps. Typically, the reactor effluent is cooled and conducted into an initial fractionator to separate the HCl and propylene from the chloropropenes, dichloropropanes, dichloropropenes, and heavier compounds. The unconverted propylene is recycled after removal of HCl, which can be accompHshed by adsorption in water or fractional distillation (33,37,38) depending on its intended use. The crude aHyl chloride mixture from the initial fractionator is then subjected to a lights and heavies distillation the lighter (than aHyl chloride) compounds such as 2-chloropropene, 1-chloropropene, and 2-chloropropane being the overhead product of the first column. AHyl chloride is then separated in the second purification column as an overhead product. Product purities can exceed 99.0% and commercial-grade aHyl chloride is typicaHy sold in the United States in purities about 99.5%. 

From Allyl Alcohol. The reaction of allyl alcohol [107-18-6] with chlorine and water gives a mixture of glycerol m on ochl orohydrin s consisting of 73% 3-chloropropane-l,2-diol and 27% of 2-chloropropane-l,3-diol (57). In a recycle reaction system in which allyl alcohol is fed as a 4.5—5.5 wt % solution, chlorine is added at a rate of 7—9 moles per hour. The reaction time is about five seconds, the reaction temperature 50—60°C and the recycle ratio is 10—20 1. Under these conditions m on ochl orohydrin s have been obtained in 88% yield with 9% dichlorohydrins (58) (see Allyl ALCOHOL AND DERIVATIVES). 

Chloropropane Isopropyl chloride 199 C,H,Cl 2-Methylpentane Isohexane 24 QHi4... 

Bromobenzene Bromochlorodifluoromethane Bromochloromethane 1 -Bromo-2-chloropropane Bromoethane... 

The stream of dry air is continued for about six hours or until most of the hydrogen chloride has been expelled and then another 55 grams of thionyl chloride is added. The reaction mixture is allowed to stand twenty-four hours, a few drops of pyridine are added and the mixture heated 4 hours on the steam bath. The cooled reaction mixture is poured into water, the crude product is washed with dilute sodium bicarbonate solution and finally taken up in benzene. The benzene is distilled at ordinary pressure and the residue distilled in vacuo to yield 60-70% of Tphenoxy-2-chloropropane, BP 93°-94°C/5 mm. 

Step 2 To 494 grams of ethanolamine, heated to approximately 150°C in a 500 ml flask equipped with stirrer, condenser and dropping funnel, is added 465 grams of 1-phenoxy-2-chloropropane with mechanical stirring. The reaction mixture is then heated to reflux for 3 hours, cooled and poured into a liter of water. The organic layer is extracted into ether and the ether solution is extracted with dilute hydrochloric acid. The aqueous acid solution is then made alkaline with 40% sodium hydroxide solution and the organic base is extracted into ether. Removal of the ether leaves N-(phenoxyisopropyl)-ethanolamine which, after recrystallization from hexane, melts at 70.5°-72°C. 

Mechanism of the Friedel-Crafts alkylation reaction of benzene with 2-chloropropane to yield isopropylbenzene (cumene). 

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