Best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain is
• Gabriel phthalimide synthesis is a chemical reaction that transforms primary alkyl halides into primary amines.
• Generally, the reaction uses potassium Pthalimide as reactant which by reaction with ethanolic KOH at first produces potassium salt of phthalimide which con heating with a certain alkyl halide (production of N-aikylpthalimide) followed by hydrolysis in alkaline medium produces the corresponding primary amine, without changing in the number of carbon atoms of the chain.
• Other 2 preparation of amines (i) Hoffmann Bromamide reaction ( product amine will have 1 carbon less than the reactant alkyl halide) and (iv) Reaction with NH3 ammonolysisof alkyl halides(the primary amine obtained can further undergo reaction with halide and forms secondary, tertiary or even quaternary amines ) are not necessarily form primary amines without changing the number of carbon atoms in the chain.