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Chemical properties of Ethers (With HI) On heating with concentrated Hydrogen iodide (HI) the C-O bond in ethers breaks forming alcohol and alkyl iodide. For example, C 2 H 5 -O-C 2 H 5 + HI ------------> C 2 H 5 - I + C 2 H 5 OH On boiling with excess of concentrated Hydrogen iodide (HI), Alkyl iodide is formed. C 2 H 5 -O-C 2 H 5 + 2HI ------------> 2C 2 H 5 I + H 2 O In the case of mixed ethers with two different alkyl groups, the site of cleavage and hence the alcohol and alkyl iodide that form depend on the nature of the alkyl groups. When one group is methyl and the other is primary or secondary alkyl group, it is the lower alkyl group that forms alkyl iodide due to steric factors. For Example, When one group is methyl and the other alkyl group is a tertiary group, the halide formed is a tertiary group, the halide formed is a tertiary halide. For Example, It is because the attack by I- takes place at that carbon of alkyl group, which has a greater electron pus...

Reaction of ethers with atmospheric Oxygen Ethers form peroxides by the action of atmospheric oxygen or ozonised oxygen due to co-ordination of one lone pair of the ethereal oxygen with another oxygen atom For example, C 2 H 5 O 2 H 5 + O ------------> (C 2 H 5 ) 2 O (diethyl ether Peroxide)---> O These peroxides are unstable compounds and decomposes violently on heating. Hence, ethers should never be evaporated to dryness. it is essential to remove the peroxides by washing before distilling the ether. This can be done by washing the ether with a solution of ferrous sulphate. For Chemical properties of ethers visit http://entrancechemistry.blogspot.com/2012/07/chemical-properties-of-ether.html

Chemical Properties of Ethers (with H 2 SO 4 ) On heating with dilute sulfuric acid under pressure, ethers are hydrolysed to alcohols. For example, C 2 H 5 OC 2 H 5 + H 2 O ----( dil.H2so4,high pressure )-----> 2C 2 H 5 OH Mixed ethers under similar conditions give a mixture of alcohols. CH 3 OC 2 H 5 + H 2 O ------( dil.H2so4,high pressure )------>C 2 H 5 OH + CH 3 OH But if concentrated sulfuric acid is used, then the products are alcohol and alkyl hydrogen sulphate. C 2 H 5 OC 2 H 5 (Diethyl ether) -----( heat, conc. H2SO4 )-----> C 2 H 5 OH (ethanol)+ C 2 H 5 OSO 2 OH (ethyl hydrogen sulphate) Ethers containing secondary and tertiary alkyl groups form alkenes with conc. sulphuric acid. For example For more about chemical reaction of ether visit http://entrancechemistry.blogspot.in/2012/07/chemical-properties-of-ether.html

The functional group in ethers (-O-) is comparatively inert with respect to the -OH functional group in alcohols and phenols even though the oxygen atom in each of the groups has two lone pairs of electrones. Therefore, ethers are not easily attacked by alkalies, dilute mineral acids, PCl 5 , metallic sodium etc. under ordinary conditions. But they undergo chemical reactions under specific conditions. 1. Cleavage of C-O bond in ethers The cleavage of C-O bond in ethers takes palce under drastic conditions with excess of hydrogen halides. The reaction of dialkyl ether gives two alkyl halide molecules. R-O-R + 2HX -------------> 2RX + H 2 O Alkyl aryl ethers are cleaved at the alkyl-oxygen bond. The reaction yields phenol and alkyl halide. Ethers with two different alkyl groups are also cleaved in the same manner. R-O-R' + H-X ------------> R-X + R'-OH The order of reactivity of hydrogen halides is as follows: HI > HBr > HCl. 1. Reaction with HI 2. Reaction ...

Lower members of ethers are gases while higher members are volatile with pleasant smell. The C-O bond in ethers are polar. They are nonlinear (angular) molecules with C-O-C bond angle of about 110 0 . Therefore, ethers are polar compounds and have a net dipole moment. For example, dipole moment of dimethyl ether is 1.3D. Ethers are isomeric with alcohols. But they do not show hydrogen bonding and association because of their low polarity. The weak polarity of ethers do not appreciably affect their boiling points which are comparable to those of alkanes of comparable molecular mass but are much lower than the boiling points of isomeric alcohols. Ethers containing upto 3 carbon atoms are soluble in water due to their hydrogen bond formation with water molecules. The increase in the size of the alkyl group decreases the polar nature of C-O bond and hence it decreases the hydrogen bonding with water. As a result solubility of ethers decreases with increase in the number of carbon atoms. Et...

Preparation of ethers using sodium alkoxide This is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, ethers are prepared by heating an alkyl halide with sodium alkoxide. Ethers containing substituted alkyl groups (secondary or tertiary) may also be prepared by this method. The reaction involves a nucleophilic substitution of halide ion by an alkoxide ion. Thus, good results are obtained if the alkyl halide is primary. If a tertiary alkyl halide is used, an alkene is the only reaction product and no ether is formed. For example, the reaction of CH3CONa with (CH3)3 C-Br gives exclusively 2 -methyl propene. It is because alkoxides are not only nucleophiles but also strong bases. They react with alkyl halides leading to elimination reactions. Since halogen attached to the benzene ring is not reactive, in order to prepare an alkyl aryl ether, a mixture of alkyl halide and sodium phenoxide must be heated. For example, ethyl phenyl et...

Preparation of Ethers by Dehydration of Alcohols When excess of a primary alcohol is heated with protonic acids like conc.H 2 SO 4 or H 3 PO 4 at 413 K , it undergoes dehydration to form an ether . 2R - OH (Alcohol) -----(conc.H 2 SO 4 , 413K)-----> R-O-R (Ether) + H 2 O 2C 2 H 5 OH (Ethanol)-----(conc.H 2 SO 4 , 413K)-----> C 2 H 5 -O-C 2 H 5 (Diethyl ether) + H 2 O But this reaction cannot be used for the preparation of unsymmetrical ethers . The formation of reaction product depends on the reaction conditions. At high temperature, if excess of acid is used dehydration occurs in a different way to form an alkene. For example, ethanol when heated with conc.H 2 SO 4 at 440K undergoes dehydration to give ethylene. CH 3 CH 2 OH -----(conc.H 2 SO 4 , 413K)-----> CH 2 = CH 2 + H 2 O The dehydration of secondary and tertiary alcohols to the corresponding ethers is unsuccessful as alkenes are formed easily in these reactions. The dehydration of alcohols can als...