4-Halogen-2-nitro

Ordinary commercial camphor is (-i-)-cam phor, from the wood of the camphor tree. Cinnamonum camphora. Camphor is of great technical importance, being used in the manufacture of celluloid and explosives, and for medical purposes, /t is manufactured from pinene through bornyl chloride to camphene, which is either directly oxidized to camphor or is hydrated to isoborneol, which is then oxidized to camphor. A large number of camphor derivatives have been prepared, including halogen, nitro and hydroxy derivatives and sulphonic acids. 

Electron-attracting substituents in the coupling components such as halogen, nitro, sulfo, carboxyl, and carbonyl, are deactivating and tend to retard coupling. 

Die Reaktion verlauft meist heftig7. Bei der Reaktion aromatischer Halogen-nitro-Derivate mit Lithiumalanat lassen sich Jod und in bestimmten Stellungen auch Brom parallel mit der Reduktion der Nitro-Gruppe hydro-genolytisch abspaltcn8. 

For aromatic amines, the reaction is very general. Halogen, nitro, alkyl, aldehyde, sulfonic acid, and so on, groups do not interfere. Since aliphatic amines do not react with nitrous acid below a pH of 3, it is even possible, by working at a pH of 1, to diazotize an aromatic amine without disturbing an aliphatic amino group in the same molecule. ... 

A variety of other functional groups such as halogen, nitro, cyano, ester, amide, and isolated double bonds are not attacked under these conditions ... 

Halogenated nitro compoands may suffer replacement of halogen during some reductions thus 9-bromo-lO-nitrophenanthrene reduced with zinc and acid, with stannous chloride, with ammonium sulfide, or with hydrazine in the presence of palladium gave 9-aminophenanthrene (87.5% yield). Reduction to 9-bromo-lO-aminophenanthrene was accomplished with iron in dilute acetic acid (yield 35%) [278]. 

Reductions of halogen, nitro, diazo and azido derivatives of esters resemble closely those of the corresponding derivatives of carboxylic acids (p. 141). 

AuBerdem konnen sowohl 1-substituierte, als auch 1-unsubstituierte Halogen-nitro-imidazole eingesetzt werden. Als Hetero-Nukleophile kommen z.B. Halogenwasserstoff, Alkanolate, Phenolate, Thiolate, Natriumsulfit, Ammoniak oder Amine in Frage. 

Neben der nukleophilen Substitution des Halogen-Atoms in Halogen-nitro-imidazolen sind auch einige Beispiele fur den Halogen-Austausch an Imidazolen mit anderen elektronenzie-henden Gruppen bekannt. 

Several derivs were obtained by H.den Otter (See Ref 2 at the end of this section) by coupling aminopropanediols with aromatic nitro- or halogen-nitro compounds. On nitration of these derivs, several compds were obtained... 

Similar studies [49,50] on the cathodic reduction of halogenated nitro-benzenes revealed the following mechanism ... 

When a hydrocarbon is substituted with other than alkyl groups a new problem arises, which can be illustrated by CH3CH2C1. This substance can be called either chloroethane or ethyl chloride, and both names are used in conversation and in print almost interchangeably. In the IUPAC system, halogens, nitro groups, and a few other monovalent groups are considered to be substituent groups on hydrocarbons and are named as haloalkanes, nitro-alkanes, and so on. 

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