The synthetic process of 3-Chloro-2-(chloromethyl)-1-propene (CAS NO. ) contains 3 steps. The synthetic route is as follows:

A. Synthesis of Pentaerythrityl trichlorohydrin: 3-Chloro-2,2-bis(chloromethyl)propan-1-ol. A dry, 5-L, four-necked, round-bottomed flask equipped with an efficient mechanical stirrer, addition funnel, thermometer adapter, and a condenser is charged with 417 g (3.06 mol) of and 730 g (9.24 mol) of pyridine. A Drierite drying tube is attached to the condenser, and the addition funnel is closed with a glass stopper after being charged with 1.134 kg (9.53 mol) of chloride. The reaction flask is placed inside a bucket to which an ice/water mixture may be added in the event that the reaction becomes too exothermic. is added dropwise with vigorous stirring to the slurry so that the white mist that appears in the flask does not rise up into the condenser. Thionyl chloride is added as rapidly as possible over 4-5 hr so that the temperature of the yellow-orange reaction mixture is maintained between 65-95°C. When the addition is complete, the drying tube is removed, and the ice bucket is replaced with a heating mantle. The resulting orange-yellow reaction mixture is heated to 120-130°C until no more sulfur dioxide is evolved. As the heating continues, the reaction mixture turns from dark orange to brown, and gas evolution becomes evident. After gas evolution ceases, the flask is cooled slightly and 2 L of cold water is added with stirring. The brown-yellow product precipitates, is filtered, and washed with 2-3 L of water. The dried, crude product (461 g) is approximately a 1:2.8 mixture of pentaerythrityl tetrachloride (131 g) and pentaerythrityl trichlorohydrin (330 g, 57% yield). This crude material may be used directly in the next step.

B. Synthesis of (chloromethyl)acetic acid: 3-Chloro-2,2-bis(chloromethyl)propanoic acid. (Caution: oxides are highly toxic. This procedure should be carried out in a well-ventilated hood!) The crude mixture (461 g) of pentaerythrityl tetrachloride and pentaerythrityl trichlorohydrin obtained from the above reaction is transferred to a 3-L, four-necked, round-bottomed flask that is equipped with an efficient mechanical stirrer, reflux condenser, thermometer adapter, and an addition funnel. The transfer is most easily accomplished by melting the solid over a steam bath and pouring the mixture through a funnel directly into the reaction flask. The flask and its contents are heated to 70-80°C with a heating mantle, and a small portion (10-15 mL) of concentrated nitric acid is added with vigorous stirring to initiate the reaction. As the reaction begins, a large amount of dark orange-brown vapors appears. Stirring is continued, and the addition of nitric acid is resumed after the initial exothermic reaction subsides (usually within 15 min). The remaining nitric acid (660-680 mL) is added in 20-30-mL aliquots over 30 to 60 min so that nitrogen oxides are continually evolved but the reaction does not become violent. After the addition is complete, the addition funnel is carefully removed and left in the hood to air out and is replaced by a glass stopper. The reaction mixture is heated at 70-80°C until the evolution of nitrogen oxides is no longer evident. At this point, the biphasic reaction mixture is a cloudy yellow or white liquid. The warm reaction mixture is poured into a 4-L beaker and 2 L of cold water is added is to precipitate the tetrachloride/carboxylic acid product mixture. The beaker and its contents are allowed to stand for several hours at room temperature to ensure complete precipitation of the product; then the crude product mixture is filtered, washed with water, and the carboxylic acid is extracted as follows. The solid is pulverized, transferred to a 4-L beaker, and 2.5 L of 1 M sodium hydroxide is added with stirring. The liquid reaction mixture instantly becomes bright yellow, and the insoluble, white tetrachloride clumps on the sides of the beaker. Stirring is continued for 30-60 min whereupon the insoluble material is filtered and washed well with water. The combined washings and yellow, aqueous filtrate are acidified to pH 1 with concentrated hydrochloric acid (250 mL). The carboxylic acid precipitates as a white solid that is easily filtered using two pieces of filter paper. The filtered and dried product thus obtained is a fine white powder (230 g, 65% yield). The aqueous filtrate is extracted with methylene chloride ; the extracts are dried with magnesium sulfate and concentrated to provide an additional 50-60 g of the desired acid. The crude, combined product (75% yield) can be used directly in the next step. Over several runs, the yield varies from 65-80%.

C. Synthesis of 3-Chloro-2-(chloromethyl)-1-propene. Tris(chloromethyl)acetic acid (205 g, 1.00 mol) is transferred to a 500-mL, two-necked, round-bottomed flask. On top of the powdery acid, which nearly fills the flask, is placed a football magnetic stir bar (1.25 × 0.5 in.). The neck of the flask to be clamped is wrapped well with aluminum foil and is fitted with a glass stopper. A standard taper 24/40 short path still head, to which is attached a Drierite drying tube, is attached at the second neck. The upper flask and short path column are wrapped with aluminum foil, and the flask is immersed in a high temperature oil bath that has been preheated to a stable 210°C. As the solid melts, the reaction mixture becomes yellow, and the oil bath temperature drops (10-20°C). If after 10-15 min, the temperature does not rise to between 205-215°C, it may be necessary to adjust the heating to maintain the oil bath temperature between 205-215°C. Moderate stirring is maintained throughout the reaction. Within 30 to 60 min, gas evolution becomes apparent, the reaction mixture turns brown, then black, and the product begins to distill. As the reaction proceeds, a black, tarry residue begins to build up on the bottom and sides of the flask. The product begins to distill, slowly at first, then quite steadily, at which point the head temperature rises to 138°C. The reaction time varies, but heating is continued until just before dryness. The product (115 g, 92% yield) thus obtained is a clear, colorless liquid (bp 136-138°C) that is > 98% pure by GLC and 1H NMR analysis. Over several runs, the yield varies from 88-99%.