Nitro compounds aliphatic, nitration

Nitro compounds. Aliphatic nitro compounds are acidic. They are freed from alcohols or alkyl halides by standing for a day with concentrated sulphuric acid, then washed with water, dried with magnesium sulphate followed by calcium sulphate and distilled. The principal impurities are isomeric or homologous nitro compounds. In cases where the nitro compound was originally prepared by vapour phase nitration of the aliphatic hydrocarbon, fractional distillation should separate the nitro compound from the corresponding hydrocarbon. Fractional crystallisation is more effective than fractional distillation if the melting point of the compound is not too low. 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Fig. 21 Reaction scheme for the detection of aromatics, by means of the reaction sequence, nitration, reduction, diazotization and coupling to an azo dye, and of aliphatic nitro compounds by detection of the primary amino group produced on reduction.

If an aromatic compound contains saturated aliphatic side chains nitration carried out under the above conditions takes place always in the benzene nucleus and not in the side chain. Since the carbon atoms of benzene are each united directly to only one hydrogen atom, the nitro-derivatives obtained are tertiary and therefore incapable of forming salts, nitrolic acids, or pseudonitroles, as do the primary and secondary nitro-compounds. 

Stokinger HE Aliphatic nitro compounds, nitrates, nitrites. In Clayton GD, Clayton EE (eds) Patty s Industrial Hygiene and Toxicology, 3rd ed, rev, Vol 2C, Toxicology, pp 4162-4164. New York, Wiley-Interscience, 1982... 

Aliphatic nitro compounds can be a nitrated [R2CHN02 —> R2C(N02)2] by treatment of... 

As early as 1929 Plyler and Steele [10] began an investigation of the infra-red spectra of nitric esters in the range methyl to n-butyl nitrates. Dadieu, Jele and Kohlrausch [11] studied the Raman spectra of nitric esters as well as inorganic nitrates, and aliphatic and aromatic nitro compounds. 

Nitro compounds and their reduction products. Tertiary aliphatic nitro compounds and aromatic nitro compounds are reduced by zinc and ammonium chloride solution to the corresponding hydroxylamines, which may be detected by their reducing action upon an ammoniacal solution of silver nitrate or Tollen s reagent ... 

Konovalov [15] nitrated aliphatic hydrocarbons in sealed tubes at 120-130°C, using dilute nitric acid of concentration 6.5-19%. From normal hydrocarbons he obtained secondary nitro compounds in yields varying from 40% (2-nitro-hexane from hexane) to 49-50% (2-nitrooctane from octane). Aromatic hydrocarbons with an aliphatic substituted group when nitrated under the same conditions gave nitro derivatives with a nitro group in the side chain. For example, ethylbenzene, when nitrated with 12.5% nitric acid at 105-108°C, gives phenyl-nitroethane in 44% yield. The optimum yield is obtained with 13% acid. 

Aliphatic nitro compounds may be obtained in the well known Kolbe reaction [197] by acting with sodium nitrate on a- halogen fatty acids. During the substitution the carboxyl group splits off. 

The molecular ion is frequently not detectable in aliphatic alcohols, nitrites, nitrates, nitro compounds, nitriles and in highly branched compounds. 

The presence of olefines is dangerous because these substances form nitro-compounds in the nitration process, and these compoimds are rather unstable. A fire or even an explosion may possibly result if the toluene is not freed from them. The presence of members of the aliphatic or paraffin series is not nearly so detrimental as the presence of the olefines. These compounds do not react on nitration, and with the three-stage process they may be removed after the nitration to mononitrotoluene. 

Group III Solid, noncyclic, aliphatic compounds containing only nitro and (or) nitrate substituents ... 

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