mirbane) + HNO Con H SO NO + H O On direct nitration of nitrobenzene m- dinitrobenzene is obtained ) Indirect method Nitration of nitro benzene gives m-dinitrobenzene. The following method is adopted for the preparation of p-dinitrobenzene. For example NH NO NaNO HBF Diazotization N BF NO NaNO (Cu) NO NO + N +NaF+BF p - nitroaniline p - nitrodiazo fluoroborate p - dinitro benzene XII U13-Organic Nitrogen XII U13-Organic Nitrogen - - - - Amino group can be directly converted into nitro group, using caro’s acid (H SO ) (or) persulphuric acid (H S O ) (or) peroxytrifluro acetic acid (F C.CO H) as oxidising agent. .
. Physical properties of nitro alkane The lower nitroalkanes are colourless pleasant smelling liquids, sparingly soluble in water, but readily soluble in organic solvents like benzene, acetone etc… They have high boiling points because of their highly polar nature. Alkylnitrites have lower boiling points than nitro alkanes. .
. Chemical properties of nitroalkanes Nitroalkanes undergo the following common reactions. i. Reduction ii.
Hydrolysis iii. Halogenations i. Reduction of nitroalkanes Reduction of nitroalkanes has important synthetic applications. The various reduction stages of nitro group are given below.
NO -H O + [H] NHOH + [H] - H O NH nitromethane nitroso methane N - methyl hydroxylamine methylamine + [H] The final product depends upon the nature of reducing agent as well as the pH of the medium. NO [H] + 2H O NH Nitromethane Methyl amine [H] Zn / NH Cl NHOH + H O N - methyl hydroxylamine Sn/HCl (acid medium) (neutral medium) Reduction of alkyl nitrites Ethylnitrite on reduction with Sn / HCl gives ethanol CH CH - O - N O + [H] Sn / HCl CH CH - OH + NH + H O ii. Hydrolysis of nitroalkanes Hydrolysis can be effected using conc. HCl or conc.
H SO . Primary nitroalkanes on hydrolysis