In this article, I will show you how to make DEET(Diethyltoluamide) in the lab.
As an insect repellent, DEET is applied to the skin or clothing to avoid mosquito bites. The principle is that DEET effectively blocks the sensation of insects on the special odor of humans or animals.
In the laboratory, DEET is synthesized from diethylamine and m-methylbenzoic acid.
M-toluoyl chloride synthesized from m-toluic acid and phosphorus trichloride, followed by aminolysis with diethylamine to form m-toluoyl chloride (or conversion of m-toluic acid to m-toluoyl chloride); The m-toluoyl chloride is reacted with diethylamine to prepare N,N-diethylm-toluamide.
Reagents: m-toluic acid, thionyl chloride, diethyl ether, diethylamine, 5% NaOH, distilled water, 10% HCl, anhydrous sodium sulfate
Equipment: reflux condenser, rubber hose, wet towel, three-necked round bottom flask, beaker, test tube, dropper, drying device, vacuum distillation unit
2.8 g of m-toluic acid was weighed into a 500 ml three-necked round bottom flask, and then 4.5 ml of thionyl chloride was added thereto, and a rubber tube was attached to the upper end, and the other end of the rubber tube was wrapped with a wet towel and placed on the sewer.
The other end of the three-necked flask is equipped with a constant pressure funnel. The reaction was slowly heated until no gas evolved.
After the reaction was cooled, 120 ml of diethyl ether was added. 7 ml of a diethyl ether solution in diethyl ether was added to the constant pressure funnel.
Repeatedly adding a small amount of diethyl ether in diethyl ether solution, while paying attention to boiling, can not make the reaction too intense, about 20~25min. In the process of addition, attention should be paid to the formation of flocculent substances.
After the addition of diethylamine, the solid adhering to the wall of the condensation tube was rinsed with a small amount of water, and 35 ml of a 5% NaOH solution was added to the solution, followed by liquid separation, and the ether layer was washed once with a 5% NaOH solution.
The ether layer was then washed once with 10% HCl and water and dried over anhydrous sodium sulfate.
After drying, the ether was distilled off, and distilled under reduced pressure at 2.7 x 103 Pa, and collected.
In the process of generating acid chloride, the gas outlet can be wrapped with a wet rag and cannot be placed together with the outlet of the condensed water. Otherwise, the suction phenomenon will occur, resulting in failure or even danger.
The rate of addition of diethylamine should be controlled. If it is added too fast, it will cause the outlet of the constant pressure funnel to clog.
When vacuum distillation, pay attention to the technical requirements of the installation, sealing, operation and other aspects of the entire device.
The reaction process is closed and fully ventilated. Self-priming filter gas masks (half masks) must be worn when the concentration in the air exceeds the standard. Air respirators should be worn during emergency rescue or evacuation.
Wear chemical safety glasses.
Wear anti-poisons to infiltrate overalls.
Wear rubber and oil resistant gloves.
Smoking is strictly prohibited at the job site.
After work, take a shower.
These are the laboratory manufacturing methods used by the Haihang industry to provide DEET. If you have any ideas, please feel free to contact us.