Chloropropyl Acetate

2-Chloromethylthiophene has been prepared by the action of hydrogen chloride on 2-thienylcarbinol and by the action of hydrogen chloride and formaldehyde on thiophene. The above procedure is essentially that of Blicke and Burckhalter.  

Submitted by C. F. H. Allen ajid F. W. Spangler. Checked by Millard Seeley and C. R. Noller. 

The solution is cooled, then washed successively with two 500-ml. portions of 10% sodium carbonate solution, one 500-ml. portion of water, and one 100-ml. portion of saturated sodium chloride solution. The wash solutions are extracted successively with one 100-ml. portion of benzene, which is added to the main benzene solution. After removal of the benzene the ester is distilled at atmospheric pressure through a 30-cm. asbestos-wrapped Vigreux colmnn, the fraction boiling at 166-170°, Mq 1.4295, being collected. The yield of colorless product is 257-260 g. (93-95%). 

The submitters prefer to use the Clarke-Rahrs ester column, for which they claim two distinct advantages (1) dehydration requires no attention beyond occasionally noting the amount of distillate—when no more aqueous layer separates the reaction is over (2) reagents do not need to be dry—any water present is removed during the heating. 

Titration of an aliquot portion of the aqueous layer with standard alkali will give the amount of acetic acid carried over, from which the amount of water can be determined. The expected amount of water is 36 ml. 

A mixture of 50 g. (0.46 mole) of yS-chloropropionic acid [Org. Syntheses Coll. Vol. 1, 166 (1941) ] and 45 g. of phosphorus trichloride is heated on a water bath for 1 hour, and 200 ml. of dry benzene is added. The resulting solution is decanted into a mixture of 75 g. (0.56 mole) of anhydrous aluminum chloride and 200 ml. of benzene. The mixture is refluxed for 1 hour and then poured into excess crushed ice. A small amount of ether is added, and the ether-benzene layer is separated and washed with water. After drying over calcium chloride, the solvent is allowed to evaporate in the air. The residual solid is recrystallized from ethanol to give 62-70 g. (80-90%) of the ketone, m.p. 57-58°. 

Three hundred grams (3.2 moles) of trimethylene chlorohydrin [Org. Syntheses Coll. Vol. 1, 533 (1941)] is stirred under a reflux condenser, and 250 g. (3.2 moles) of acetyl chloride is added slowly. (Hood.) After the acetyl chloride is added, the reaction mixture is heated under reflux until evolution of hydrogen chloride ceases. Distillation of the resulting material gives 375 g. (86%) of y-chloro-propyl acetate boiling at 160-166°. 

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Chloropropyl acetate has been prepared by heating 1-bromo-3-chloropropane and potassium acetate in glacial acetic acid, and by the action of acetyl chloride on trimethylene chlorohydrin. ... 

Acetyl chloride 2-Chloro-1 -methylethyl acetate, 2-chloropropyl acetate 2-Chloroethyl acetate For EO content <30%, the ratio of chloroethyl acetate to total chloroethyl and chloropropyl acetates may be used to obtain percent of EO. A calibration is required for values of EO >30% [16]. 

The same method can also be used to generate larger cyclic ethers. Oxetanc, for example, is conveniently made by adding 3-chloropropyl acetate to hot potassium hydroxide. 

Trimethylene oxide and its homologs are prepared from the corresponding trimethylene chlorohydrins and alkali. The yield is higher when y-chloropropyl acetate is substituted for the chlorohydrin (44% vs. 

A mixture of 150 g. (2.6 moles) of potassium hydroxide and 12 ml. of water is placed in a 500-ml. flask. A thermometer is placed in the reaction mixture, and one neck of the flask is connected to two receivers in series each of which is cooled in an ice-hydrochloric acid mixture. The reaction mixture is heated to 100° (inside temperature) and agitated while 75 g. (0.55 mole) of y-chloropropyl acetate (p. 83) is added slowly over a 1-hour period. The reaction mixture is held at 100-110° during this operation and at 120° for 10 minutes after completion of the addition. The distillates in the receivers from two such runs are combined (29 g.) and cooled in a freezing mixture, and bromine is added dropwise until there is a slight permanent color. The mixture is then distilled from a water bath and the distillate is allowed to stand for 24 hours over anhydrous sodium sulfate. Distillation gives 14 g. (22 ) of trimethylene oxide, b.p. 48-50°/750 mm. 

Esterification. The preparation of y-chloropropyl acetate was accomplished by heating the components in benzene with a little tosic acid under a Vigreaux column CHjCOjH + HOCH2CH2CH2CI + TsOH HjO + C Ht ---------------CHjCOjCHjCHjCHjCl... 

A simple esterification employing azeotropic removal of water by means of a Dean and Stark trap can be used in an introductory organic laboratory course. This technique is widely used in industry for the preparation of polyesters. The preparation of y-chloropropyl acetate in 93-95% yield and of n-amyl acetate in 71% yield have been described. 

Acetyl chloride cleavage is also applicable to analysis of block EO/PO copolymers, as well as products containing butylene oxide (68). Propylene oxide groups are converted mainly to 2-chloro-l-methylethyl acetate and 2-chloropropyl acetate, with traces of 1,2-propylene diacetate. Simple GC determination of the ratio of chloroethyl acetate to total chloroethyl and chloropropyl acetates provides an accurate figure for EO content of copolymers up to about 30% EO. A calibration curve must be used for higher ratios (69). 

Isopropylidene [l-(3-chloropropyl)piperidin-2-ylidene]malonate (1624) in refluxing ethanol in the presence of boron trifluroide etherate was transformed into ethyl [l-(3-chloropropyl)piperidin-2-ylidene]acetate (1625) in 90% yield (87H2335, 89T6161). Similar reaction was also carried out with isopropylidene [l-(2-chloroethyl)pyrrolidin-2-ylidene]malonate (89T6161). 

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