Dicyclohexylcarbodiimide

DCC

1. Advanced Organic Chemistry Synthetic reagent Presentation Dicyclohexylcarbodiimide (DCC) S. Maheen Abdul Rahman , M. Pharm., Department of Pharmaceutical Chemistry

2. Table of contents: Introduction Properties Preparation DCC involving chemical reaction Application

3. Introduction N , N' - Dicyclohexylcarbodiimide : N ′Dicyclohexylcarbodiimide  ( DCC  or  DCCD )   is an   organic compound  with the chemical formula (C 6 H 11 N) 2 C . Sheehan and Hess introduced the use of dicyclohexylcorbodiamide  ( DCC ) as a coupling reagent for the preparation of  amide  bonds in 1955 . And DCC has been used since then for peptide synthesis.

4. Properties DCC is a waxy white solid with a sweet odor. Its primary use is to couple amino acids during artificial  peptide synthesis. The low melting point of this material allows it to be melted for easy handling. It is highly soluble in dichloromethane, tetrahydrofuran , acetonitrile and   dimethylformamide but insoluble in  water . The melting point is 30-35 o C The boiling point is 122-124 o C And the molecular weight of DCC in 206.33  g/mol.

5. Prepration Dicyclohexylcarbodiimide may be prepared by any of the methods given below: By the Oxidataion of N,N’- dicyclohexylthiourea eith mercuric oxide(Mg 2 O) By the Dehydration of Dicyclohexylurea with p- toluene sulphonyl chloride in hot pyridine

6. DCC involving Chemical reaction: 1. Synthesis of Esters: The esterification of acids with primary or secondary alcohols promoted by DCC Mechanism of Reaction: This reaction is catalysed by acids. The acid in first step reacts with the reagent to form a compound I which is a good leaving group. Subsequent reaction of compound I with alcoho in second step to gives ester with the removal of dicyclohexylurea .

7. , 2. Synthesis of amides: The amides not directly obtained by reacting acids with amine, here the reagent first convert the acid to its anhydride form, which is further reacts with amine to produce amide.

8. , 3. Synthesis of Ethers: A mixture of phenol, alcohol and the reagent on prolonged heating under the pressure to produce aryl alkyl ether. 4. Synthesis of Acid anhydride: The reagent gives excellent yield of acid anhydride from carboxylic acids And also this reagents to produce symmetrical anhydrides from N- substituted amino acids(Phenylalanine derivatives)

9. , 5. Synthesis of Diacyl peroxide: Diacyl peroxide can be synthesized by the treatment of carboxylic acids with hydrogen peroxide under the mild condition with DCC 6. Synthesis of lactones: [ DCC in pyridine ] has been found to be a better reagent for the synthesis of lactone by the lactonization of γ - hydroxy acids. And also this method has been widely used in the synthesis of Reserpine .

10. .. 7. Synthesis of Lactams : Lactams are cyclic amides. Β - Lactams are highly strained ring, sensitive to acids while most reagents for amide linkage involves strongly acid reagents. This caused a serious problems in penicillin synthesis. However , the difficulty was overcome by using DCC for the amide linkage. Di isopropyl carbodiimide also has been found to be a better reagent for amide ring formation but it is very mild reagent! 8. Synthesis of Peptides: The amino acids in the amino function has been protected by Pthalyl [ C 6 H 4 (CO) 2 ] or Carbobenzoxy [C 6 H 5 CH 2 –O–C=O] condense with amino acid esters in the presence of DCC at room temperature to gives Peptides.

11. . After hydrolysis of product the protecting group ( Pthalyl group) which is removed by hydrazine ( like Gabrial synthesis) Pthalyl and Carbobenzoxy groups are used as a protecting groups , since they can be easily substitutesd and easily removed after synthesis of particular products by Hydrogenolysis with [Pt + H 2 ].

12. Application N,N'-Dicyclohexylcarbodiimide is a carbodiimide used  to couple amino acids during peptide synthesis which is done by Sheehan and Hess in 1955. N,N'-Dicyclohexylcarbodiimide is used as a dehydrating agent for the synthesis of amides, ketones , nitriles as well as in the inversion and esterification of secondary alcohols. DCC has been foun to be very useful reagent for the synthesis of Lactam ring ( β - lactum in penicillin)

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