Nitro compounds, aliphatic hydrolysis

Primary or secondary aliphatic nitro compounds can be hydrolyzed, respectively, to aldehydes or ketones, by treatment of their conjugate bases with sulfuric acid. This is called the Nef reaction Tertiary aliphatic nitro compounds do not give the reaction because they cannot be converted to their conjugate bases. Like 16-2, this reaction involves hydrolysis of a C=N double bond. A possible mechanism is" ... 

While aromatic nitro and azoxy compounds have been reduced to azo compounds with lithium aluminum hydride, aliphatic nitro compounds produced only the corresponding aliphatic amines [65]. The usual technique involves dropwise addition of 1 mole of nitro compound in ether to 1.05-1.15 moles of lithium aluminum hydride in ether solution at Dry Ice temperatures followed by warming to room temperature. If the resulting product is only slightly soluble in ether, hydrolysis should be carried out with dilute sulfuric acid. Then the azo compound simply needs to be filtered off, washed with water, and dried. If the product is ether-soluble, the ether layer is separated, evaporated, and the residue is recrystallized [65, 66]. 

Hydrolysis of Aliphatic Nitro Compounds Oxo-de-hydro,nitro-bisubstitution... 

Aliphatic nitro compounds are versatile building blocks and intermediates in organic synthesis,14 15 cf. the overview given in the Organic Syntheses preparation of nitroacetaldehyde diethyl acetal.16 For example, Henry and Michael additions, respectively, lead to 1,2- and 1,4-difunctionalized derivatives.14 18 1,3-Difunctional compounds, such as amino alcohols or aldols are accessible from primary nitroalkanes by dehydration/1,3-dipolar nitrile oxide cycloaddition with olefins (Mukaiyama reaction),19 followed by ring cleavage of intermediate isoxazolines by reduction or reduction/hydrolysis.20 21... 

Few aliphatic nitro compounds are wanted as target molecules in their own right but the nitro group is important in synthesis because it can be converted into two functional groups in great demand amines 7, by reduction, and ketones 5, by various forms of hydrolysis. 

The alkylation and reduction of aliphatic nitro compounds is one route to t-AlkNH2 and is discussed in Chapter 22. Another route uses the Ritter reaction followed by hydrolysis of the amide. 

Aliphatic nitro compounds serve as good acyl anion equivalents. After electrophilic alkylation at the a-carbon atom, they can be converted into carbonyl compounds by the Nef reaction or by reductive hydrolysis with titanium(III) chloride. The a-nitro carbanions serve as excellent donors in Michael addition reactions with a, -unsaturated systems and therefore the sequence of Michael addition followed by reductive hydrolysis of the nitro group provides a good route to 1,4-dicarbonyl compounds. ds-Jasmone, for example, was readily obtained by using this strategy (1.111). 

Water and salt solutions dilute acids and alkalis have little effect at room temperature but, at elevated temperatures, some hydrolysis and extraction of the plasticizer may occur. Concentrated acids and alkalis hydrolyse plasticizers slowly when cold but, more rapidly when heated. Most organic liquids will extract plasticizers and cause compound hardening however, some organic liquids also cause softening. For example, aromatic and chlorinated hydrocarbons, aliphatic and aromatic nitro compounds, ketones, aliphatic and cyclic... 

Similarly, aliphatic a-nitro esters and nitrogen oxides do not give compounds resembling pseudonitrols but lose the nitro group and afford the aliphatic nitroso esters.164,279,280 On nitrosation of ethyl 2-benzoylpropionate the hydrolysis can be avoided and ethyl 2-benzoyl-2-nitrosopropionate can be isolated.281... 

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