Lauroyl chloride is an important organic intermediate and is widely used in the synthesis of surfactants.
Therefore, the haihang industry will introduce several major synthetic methods of lauroyl chloride.
Phosphorus trichloride as acyl chloride
A certain amount of lauric acid (200g) was placed in a dry and clean 500mL four-necked flask, heated to 60-70 ° C to melt lauric acid, control temperature 60-70 ° C, phosphorus trichloride was added dropwise, and the addition was completed within 2 hours. . The reaction was incubated at 60-70 ° C for 2-3 h, and after standing, the solution was allowed to stand for 12 h. The lower layer of phosphorous acid was separated, and the supernatant was dehydrated for 60 h at 60-70 ° C under reduced pressure. The separated product was collected by distillation under reduced pressure, and the purity of GC was ≥95%, and the yield was 97%.
Phosphorus trichloride is used as the acyl chloride agent to obtain the best color of the product, and the phosphorus trichloride is inexpensive and the production cost is low. Now most companies adopt such a method for producing acid chloride, but the purity of the product prepared by this route is high. Relatively low, phosphorus trichloride is a highly toxic chemical, and transportation and management are strict. In the industrialization, a large amount of phosphorous acid waste liquid is generated. In order to reduce the environmental protection pressure, the produced by-product phosphorous acid can be recycled and used as a sodium phosphite for sale, thereby reducing production costs and solving environmental problems. Considering its cost, it is a relatively economical route suitable for industrial production.
Sulfoxide as acyl chloride
A certain amount (about 200 g) of dodecanoic acid was added to a dry 500 mL four-necked flask, and the temperature was raised to 60-70 ° C to dissolve the lauric acid, and the thionyl chloride was added dropwise at a controlled temperature of 50-70 ° C, and the dropwise addition was completed within 2 hours. Control at 55-70 ° C, stir the reaction for 2-4 h. Distilled under reduced pressure, distilling off excess thionyl chloride to obtain a light yellow pungent odor liquid, and then purifying by vacuum distillation to obtain a colorless transparent pungent odor liquid, GC purity ≥97%, yield 85%, yellow transparent liquid .
The synthesis route using thionyl chloride as the acid chloride, although the conversion rate is high, the obtained product has poor color and needs further distillation and purification, and the final product yield is 83-85%. During the distillation process, a large amount of residue is generated, and the sulfur dioxide gas generated in the reaction corrodes the equipment and pollutes the environment.
Solid phosgene as acyl chloride
Toluene and BTC solution were added to a dry 500 mL four-necked flask, the stirrer and oil bath heater were started, the temperature was controlled at 25-30 ° C, and the toluene solution containing the raw material (200 g) and DMF was added dropwise within 2 hours. 3 hours, the conversion rate of the raw material was 100%, the reaction liquid was fractionally distilled under reduced pressure, and toluene and DMF were fractionated to obtain a product having a purity of 98%, a yield of 96%, and a pale yellow transparent liquid.
Solid phosgene is an ideal substitute for phosgene. Solid phosgene is used as an acid chloride chlorinating agent. It is found in the experiment that the operation is safe, the reaction activity is high, the reaction is mild, the conversion rate of raw materials can reach 100%, and the fractionated toluene can be recycled. The product has less by-products and the yield is up to 98%. The cost is close to that of the phosphorus trichloride. It can be used as an ideal alternative route for the phosphorus trichloride route, and industrialization is easier to achieve.