Nucleophilic displacement with nitrate anion 97presence of secondary hydroxy groups. This is illustrated in the case of glycerol (26), which
on treatment with one and two equivalents of thionyl chloride nitrate in THF, forms glyceryl-
1-nitrate (27) and glyceryl-1,3-dinitrate (28) respectively. Thionyl nitrate is a less selective
reagent. Treatment of glycerol (26) with three equivalents of thionyl nitrate in THF yields
nitroglycerine (1) in quantitative yield. Both reagents are suitable for theO-nitration of acid
sensitive substrates but have found little use, probably because more convenientO-nitrating
agents are available for such substrates.
3.3 Nucleophilic displacement with nitrate anion
3.3.1 Metathesis between alkyl halides and silver nitrate
The reaction of alkyl halides with silver nitrate constitutes an extremely useful method for
the synthesis of high purity nitrate esters on a laboratory scale.^60 −^68 The driving force for
these reactions is the formation of the insoluble silver halide. Reactions have been conducted
under homogenous^61 ,^63 and heterogeneous conditions.^60 ,^68 For the latter a solution of the alkyl
halide in an inert solvent like benzene or ether is stirred with finely powdered silver nitrate.
However, this method has been outdated and reactions are now commonly conducted under
homogeneous conditions using acetonitrile as solvent.
The scope of these reactions is illustrated by the variety of functionalized nitrate esters which
can be prepared (Table 3.1). In general, primary and secondary alkyl iodides and bromides
HOCH 2 CH 2 ONO 2N CCH 2 ONO 2CH 2 ONO 2NO 2NO 2ONO 2OCH 3 CH 2 ONO 2213467HOCH 2 CH 2 BrN CCH 2 ICH 2 Br
NO 2NO 2NO 2NO 2O 2 N O 2 NBrOCH 3 CH 2 IFCH 2 OCH 2 ClClCH 2 OCH 2 ClRX RONO 2AgNO 3CH 3 CNAgXO 2 NOCH 2 OCH 2 ONO 2Table 3.1
Synthesis of nitrate esters from the reaction of alkyl halides with silver nitrateEntry Substrate Product Yield (%)727032726482X = Cl, Br, I+Ref.5---606161626364C^65NO 2NO 2FCHC 2 OCH 2 ONO 2