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Chemical properties of d- limonene

The chemical properties of limonene are relatively stable and can be distilled without decomposition. (R)- limonene is racemized when heated to 3℃. If the temperature is higher, limonene is decomposed into isoprene.

It is easily oxidized to carvonol and carvone in humid air. When it reacts with sulfur, it loses water to produce p-cymene, and also produces hydrogen sulfide and some thioethers.

when heated with inorganic acid * * *, it is isomerized into α-terpinene with * * conjugated diene structure, and the latter is easily oxidized to generate aromatic p-cymene. When limonene and maleic anhydride are heated, adducts generated by Diels-Alder reaction between maleic anhydride and α-terpinene can be obtained.

limonene can react with olefins in general, in which both double bonds can react, or the conditions can be controlled so that only one of the double bonds can react. When treated with anhydrous hydrogen chloride/hydrogen bromide, disubstituted olefins first add with hydrogen halide; However, when mCPBA is used for epoxidation, trisubstituted olefins are epoxidized first to produce limonene oxide. If mCPBA is excessive, both double bonds are epoxidized to obtain limonene dioxide.

The acyclic double bond of D-limonene can be added with trifluoroacetic acid in toluene by anti-Markov rule. After the reaction, trifluoroacetic acid is hydrolyzed with sodium hydroxide to obtain (S)- (? )-α-terpineol (terpineol).

limonene can also be added with water in the presence of inorganic acid to produce α -terpineol and hydrated terpinediol.

when limonene is treated with nitrosyl chloride, the intramolecular double bond of limonene reacts with NO? Cl is added to generate 1- chloro -2- nitroso compound, and α-chlorooxime is obtained by tautomerization, then unsaturated carvone oxime is obtained by removing hydrogen chloride with alkali, and finally the corresponding ketone-carvone is obtained by hydrolyzing the oxime with dilute sulfuric acid. This is the main method to prepare carvone in industry.