Amines halo nitro compounds

It should, however, be noted that aromatic amino-nitro compounds are often more conveniently prepared by heating a halo-nitro compound with ammonia or an amine (e.g., N,N-dimethy -o- and -p-nitroaniline194) or by partial reduction of a polynitro compound (cf. pp. 463 et seq. and 575). 

Reduction of ArN02.4 Aromatic nitro compounds are reduced by SnCl2 2H20 in ethanol or ethyl acetate at 70° to amines in 90-99% yield. Under these conditions, carbonyl, cyano, halo, and benzyl groups are not reduced. 

Reduction of nitroalkenes. Vinyl nitro compounds are reduced to saturated ketones or aldehydes by Raney nickel and an aqueous solution of sodium hypophosphite. Ester groups, C=C bonds, and aryl NO, and halo groups are not reduced. Under these conditions nitroalkanes arc reduced to amines, and oximes are converted into carbonyl compounds in high yield. 

Reduction of NO. This Ti(ll) reagent reduces aromatic and aliphatic nitro compounds to amines in THF/r-butyl alcohol at 0° in yields of 85-95%. Halo, cyano, and ester groups are not reduced. 

Titanium(II) reagents have also been used to reduce aliphatic nitro compounds to amines halo, cyano and ester groups are not reduced. Sodium borohydride, in the presence of catalytic amounts of nickel(II) chloride, reduces a variety of aliphatic nitro compounds to amines. Nickel boride (Ni2B) is an active catalyst for reductions of primary, secondary and tertiary nitro aliphatic compounds to amines. The reduction of nitrocyclohexane (45) yields cyclohexylamine (47) as well as small amounts of dicyclohexylamine (49), the latter being formed via reaction of intermediates (46) and (48 equation 28). 

Selenolates such as Na2Se, NaSeH, PhSeNa, etc., and tellurolates such as NapTe, NaTeH, PhTeNa, etc., are excellent nucleophiles and can reduce a variety of functional groups by nucleophilic attack or single electron-transfer. On treatment with alkali metal selenolates (or amine salts of HpSe and PhSeH), reduction or reductive selenation of ketones and aldehydes, C=C reduction of a,/l-unsaturated compounds, and reduction of nitrogen compounds such as nitro compounds occur successfully [118, 176]. Compared with these selenolate anions, the corresponding tellurium compounds are highly reactive not only toward the same substrates but also toward halo compounds such as a-bromo ketones and vic-dibromoalkanes [46, 52, 177]. 

Sulfoxidation. Heteroatom oxidation catalyzed by (halo)peroxidases has been observed in a variety of organic compounds. Ai-Oxidation in amines, for instance, can lead to the formation of the corresponding aliphatic A-oxides or aromatic nitroso or nitro compounds. From a preparative standpoint, however, sulfoxidation of thioethers is of greater importance since it was shown to proceed in a highly stereo- and enantioselective fashion. Moreover, depending on the source of the haloperoxidase, chiral sulfoxides of opposite configuration could be obtained (Scheme 2.179). 

This reaction is carried out in the same manner as the diazotization of primary amines. Most azides ate relatively unstable compounds and explode upon heating. Hydrazides of all types of acids have been converted to azides. Halo alkoxyl, and nitro groups on an aromatic nucleus do not interfere. The reaction is illustrated by the preparations of p-nitrophenylacetyl azide (84%) and 6-methylnicotinyl azide (70%). ... 

This shows that aromatic compounds are not all mercurated at the same speed in fact, amines, phenols, and aromatic ethers react especially readily, aromatic hydrocarbons such as benzene more slowly, and halo- and nitro-benzenes particularly slowly. 

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