4-Nonanoylmorpholine

4-Nonanoylmorpholine (pelargonic acid morpholide, N-nonanoylmorpholine, MPK or МПК (for морфолид пеларгоновой кислоты), or MPA) is an amide of pelargonic acid and morpholine.

Properties
4-Nonanoylmorpholine was first synthetized in 1954 by L.M. Rice, from morpholine and chloroanhydride of pelargonic acid.

It is a liquid insoluble in water and soluble in polar organic solvents (eg. acetone, propanol, dimethyl formamide, and benzene) and fats. Its volatility is 27 mg/m3 at 20 °C and 43 mg/m3 at 35 °C.

Uses
It is a lachrymatory agent with about 5 times the potency of chloroacetophenone. It is comparable to adamsite. It is effective against dogs. It starts being effective in concentrations of over 20-40 mg.min/m3. It is considered very safe, with high differences between effective and toxic concentrations. At one time it was reportedly used as food seasoning. However, its effectiveness when used alone is rather low even in the highest permitted concentration, so it is often used in combination with CR gas or CS gas. In that combination, it is effective even against dogs and people under influence of alcohol or drugs. Its effect usually lasts for 15-30 minutes.

MPK is a common personal self-defense chemical agent in Russia and Ukraine, but is virtually unknown elsewhere.

Natural occurrence
4-Nonanoylmorpholine naturally occurs as a pheromone of Aedes aegypti mosquitoes.