Give reasons:
1. thionyl chloride is preferred reagent for converting ethanol to chloroethane
2. Tert-butyl bromide has lower bioling point than n-butyl bromide
3. although alkyl halides are polar in nature they are not soluble in water
1. thionyl chloride is preferred reagent for converting ethanol to chloroethane
2. Tert-butyl bromide has lower bioling point than n-butyl bromide
3. although alkyl halides are polar in nature they are not soluble in water
1)Preparation of alkyl chlorides from alcohols by thionyl chloride is preferred over other methods mentioned because of the following reasons :
R−OH+PCl5⟶R−Cl+POCl3+HCl↑R−OH+PClX5⟶R−Cl+POClX3+HCl↑ 3R−OH+PCl3⟶3R−Cl+H3PO33R−OH+PClX3⟶3R−Cl+HX3POX3 R−OH+SOCl2⟶R−Cl+SO2↑+HCl↑R−OH+SOClX2⟶R−Cl+SOX2↑+HCl↑ -
Both the byproducts formed in the last reaction i.e.,SO2SOX2andHClHClare gases and can easily escape out into the atmosphere, so the equilibrium shifts more to the right side and hence, more products are obtained.
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Moreover as both the gases easily escape out leaving behind pure alkyl halide in the last reaction, the purification process is minimized and thus the alkyl halide obtained can be easily purified.
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2) The boiling point decreases with increase in branching. This is because molecule becomes more spherical with less surface area. 3)
Alkyl halides have dipole dipole attraction among them and Hydrogen molecules consist of hydrogen bonding or wanderwal's forces of attraction it is difficult for Alkyl halides to break these bonds. So Alkyl halides are insoluble in water.
To make them soluble a high amount of energy is required that can overcome the attraction between Alkylhalide and break the bonding in hydrogen.
1)Preparation of alkyl chlorides from alcohols by thionyl chloride is preferred over other methods mentioned because of the following reasons :
R−OH+PCl5⟶R−Cl+POCl3+HCl↑R−OH+PClX5⟶R−Cl+POClX3+HCl↑ 3R−OH+PCl3⟶3R−Cl+H3PO33R−OH+PClX3⟶3R−Cl+HX3POX3 R−OH+SOCl2⟶R−Cl+SO2↑+HCl↑R−OH+SOClX2⟶R−Cl+SOX2↑+HCl↑-
Both the byproducts formed in the last reaction i.e.,SO2SOX2andHClHClare gases and can easily escape out into the atmosphere, so the equilibrium shifts more to the right side and hence, more products are obtained.
-
Moreover as both the gases easily escape out leaving behind pure alkyl halide in the last reaction, the purification process is minimized and thus the alkyl halide obtained can be easily purified.
-
2) The boiling point decreases with increase in branching. This is because molecule becomes more spherical with less surface area. 3)
Alkyl halides have dipole dipole attraction among them and Hydrogen molecules consist of hydrogen bonding or wanderwal's forces of attraction it is difficult for Alkyl halides to break these bonds. So Alkyl halides are insoluble in water.
To make them soluble a high amount of energy is required that can overcome the attraction between Alkylhalide and break the bonding in hydrogen.
