1,3-dicyclohexylcarbodiimide

Dicyclohexylcarbodiimide can be obtained from dicyclohexyl urea under the action of phosphorus (V) oxide . Another method is based on the reaction between cyclohexylamine and cyclohexyl isocyanide ^[1] .

Dicyclohexylcarbodiimide is highly soluble in methylene chloride , tetrahydrofuran , acetonitrile , dimethylformamide ^[2] .

The main field of application of this reagent is the synthesis of amides, ethers and anhydrides, where it exhibits the properties of a powerful dehydrating agent. Already after the first reports of the discovery in 1955, dicyclohexylcarbodiimide began to be used in the synthesis of peptides and other reactions where the formation of an amide bond occurs. A typical technique is to add a reagent (1.1 eq.) To a concentrated (0.1-1.0 M) solution of carboxylic acid (1 eq.), Amine (1 eq.) And catalyst in methylene chloride or acetonitrile at 0 ° WITH. During the reaction a precipitate of dicyclohexylurea (the hydration product of dicyclohexylcarbodiimide) is formed. As a rule, the reaction ends in an hour. Tetrahydrofuran and dimethylformamide are also used as solvents, however, they reduce the reaction rate and cause the formation of a by-product N- acyl urea, as well as racemization of chiral carboxylic acids. These problems can be solved by adding cross-linking reagents such as hydroxybenzotriazole (HOBt), hydroxysuccinimide (HOSu), etc. These additives are also necessary in cases where the reagents are hindered or when the nucleophilic properties of the amine are lowered ^[2] .

Dicyclohexylcarbodiimide is used in the synthesis of anhydrides. Among similar reagents ( acetic anhydride , trifluoroacetic anhydride , phosphorus oxide, etc.), it is one of the most effective, simple, and mild ^[2] .

Also dicyclohexylcarbodiimide catalyzes the oxidation reaction of primary and secondary alcohols under the action of dimethyl sulfoxide ( Moffat reaction ) ^[2] .

Dicyclohexylcarbodiimide causes acute skin irritation in sensitive people. The substance has a low melting point, so it is convenient to handle it in a liquid state. Dicyclohexylcarbodiimide should be handled under a glove and with gloves, and it should be kept out of moisture ^[2] .

• Sigma-Aldrich. IR spectrum of dicyclohexylcarbodiimide (Neopr.) . The appeal date is January 4, 2015.
• Sigma-Aldrich. CR spectrum of dicyclohexylcarbodiimide (Neopr.) . The appeal date is January 4, 2015.
• Sigma-Aldrich. NMR spectrum of dicyclohexylcarbodiimide (Neopr.) . The appeal date is January 4, 2015.