ETHERS ORGANIC CHEMISTRY Only for F.Y.B.Sc. Prof. Shrimandilkar Sagar Ramdas ( M. Sc. SET , NET-JRF , GATE ) Assistant Professor Department of Chemistry Sangamner College, Sangamner

Definition: The organic compound containing C-O-C linkage called ether Definition: The organic compound containing C-O-C linkage called ether. •The general formula for ether is CnH2n+2O •Ethers are represented by R-O-R ,Ar-O-R or Ar-O-Ar

Classification of ether: Symmetrical ether. Unsymmetrical ether(Mixed ether). 1) Symmetrical ether: When two alkyl or aryl groups in ether are same, the ether is said to be symmetrical ether. e.g. - Diethyl ether, dimethyl ether,etc. 2) Unsymmetrical ether: When two alkyl or aryl group in ether are different, the ether is said to be unsymmetrical ether. e.g.- ethylmethylether

Nomenclature of Ether Common name system:- In this system of nomenclature ,the ethers are named according to the alkyl Or aryl group attached to the oxygen atom & the word ether is placed after it.

IUPAC system In this system ether are regarded as a hydrocarbon in which H atom is replaced by alkoxy group .The large group is chosen as the parent alkane.

Physical Properties The lower members are gases or volatile liquid & their vapors are highly inflammable. Ethers show some dipole moment. The B.P. of ethers is much lower than those of alcohols of the same number of carbon atom because ethers cannot associate through hydrogen bonding.

Preparation of ether Industrial Preparation : Alcohols are heated with concentrated Sulphuric acid at 140o C to form alkyl hydrogen sulphate which reacts with excess alcohol to form symmetrical ether.

Laboratory Preparation Williamson Synthesis : This method is most useful for the formation of symmetric as well as unsymmetrical ethers When alkyl halide reacts with sodium alkoxide or sodium phenoxide gives ether. General reaction:-

Alkoxy mercuration-demercuration:- Alkene react with mercuric trifluoroacetate in the presence of alcohol to give mercurial compound which on reduction by sodiumborohydride give ether. General reaction:

Diazomethane method: This method is used to prepare methyl ether only. When alcohol or phenol is heated with diazomethane in presences of Fluroboric acid, give methyl ether.

Reaction of ethers a) At cold condition: - 1) Reaction with conc. HI : simple ether reacts with conc. HI in cold to give alcohol & alkyl iodide. In case of reaction of mixed ether higher alkyl group form alcohol.

At Hot condition:- Simple ether as well as mixed ether react with hot conc. HI to form alkyl iodide.

Reaction with dil. H2SO4 : When steam is passed over the ether under pressure in presence of dil. H2SO4 to form alcohol.