8 Synthetic Routes to AliphaticC-Nitro
XCH 2 (CH 2 )nCH 2 XO 2 NCH 2 (CH 2 )nCH 2 NO 2NaNO 2 , DMF
phloroglucinol,
(NH 2 ) 2 COX = I or Bror
AgNO 2 , Et 2 OTable 1.2
Synthesis of dinitroalkanes from the reaction of dihaloalkanes with silver nitrite
and sodium nitrite (ref. 75–79)Homologue Yield (%) of dinitroalkanen =1 2 3 4 5 6 7 8diiodide/AgNO 2 dibromide/AgNO 2 dibromide/NaNO 23775
4675
4575
4875
6076
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50772078
3778
5378
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10078679
3379
2979
4279
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---------the carbon chain give much lower yields of nitro compound.^64 Reactions with such substrates
are much slower and nitrite ester formation is much more of a problem. In fact, the nitrite
ester and the corresponding alkene can be the main products of the reaction of a secondary
alkyl halide with silver nitrite. Consequently, the Victor Meyer reaction is not considered
useful for the synthesis of secondary nitroalkanes. Nitrate ester by-products^72 ,^73 can arise from
either disproportionation of silver nitrite,^72 a process accelerated by heat and light, or from
dehydrohalogenation^64 of the alkyl halide substrate.
The Victor Meyer reaction is remarkably versatile and tolerant of many functional groups,
providing a route to arylnitromethanes^69 from benzyl iodides and bromides,α-nitroesters^68
fromα-iodoesters, and nitro-substituted epoxides like 1-nitro-2,3-epoxypropane, 1-nitro-2,3-
epoxybutane, and 3-nitro-1,2-epoxybutane from the corresponding iodoepoxides^74 (Table 1.1).
The Victor Meyer reaction has also been used for the synthesis of numerousα,ω-dinitroalkanes
from the correspondingα,ω-diiodoalkanes^75 –^77 andα,ω-dibromoalkanes^78 where yields of 37–
50 % are reported (Table 1.2). 1,5-Dinitropentane (62 %), 1,8-dinitrooctane (64 %) and 1,10-
dinitrodecane have recently been synthesized from the correspondingα,ω-diiodoalkanes using
water as the reaction solvent.^80 Kornblum^81 has compiled a comprehensive list of reactions
illustrating the versatility of the Victor Meyer reaction.
With regard to the mechanism of the Victor Meyer reaction, it is thought that both SN2 and
SN1 transition states play a role in product ratios.^69 ,^82 Both transition states are known to be
highly dependent on the nature of the substrate, the solvent and the reaction conditions used.^83
Which mechanism or combination of mechanisms is operating is important from a practical
point of view; the more SN1 character in these reactions the more nitrite ester formed via attack
on an intermediate carbocation. Unsurprisingly, the reaction of silver nitrite with tertiary alkyl
halides is not a viable route to tertiary nitroalkanes.^64 The formation of the silver halogen bond
is a strong driving force for the Victor Meyer reaction, and consequently, sulfonate esters, and
other substrates containing equally good leaving groups, fail to react with silver nitrite.^69