Silver(I) Nitrite

AgNO2

[7783-99-5]  · AgNO2  · Silver(I) Nitrite  · (MW 153.88)

(preparation of aliphatic nitro compounds2 and N-nitroso compounds;8,9 aromatic nitration;6,7 preparation of other reagents such as nitryl iodide,10 phenylselenium nitrite,14,15 thionyl chloride nitrite,16 and palladium complexes17,18)

Physical Data: mp 140 °C (dec); d 4.453 g cm-3.

Solubility: sol water, acetonitrile, acetic acid, NH4OH; insol alcohol.

Form Supplied in: pale yellow solid; widely available.

Introduction.

The main use of AgNO2, particularly in the older literature, is in the Victor Meyer1 reaction for the preparation of primary nitroalkanes from the corresponding primary bromo- or iodoalkanes (eq 1). Good conditions for this reaction have been established2 and, provided the reaction temperatures are kept low, the amount of the nitrite ester can be kept to a minimum. Higher temperatures3 shorten the reaction time, but lower yields are obtained. The reaction is best suited for alkyl halides with >3 carbon atoms, although, exceptionally, in a series of o-ethoxyalkyl bromides, the reaction was successful only for a four-carbon chain.4 Branching on the bromoalkyl halide at the g-carbon does not seriously affect the yield of nitro product, but branching on the b-carbon atom lowers the yield considerably.2a The reaction is generally unsuccessful for secondary and tertiary halides although, in an analogous reaction,5 adamantyl hexafluoroantimonate gives 1-nitroadamantane (eq 2) on treatment with AgNO2 using Arsenic(III) Fluoride as a suitable (sic) solvent. The corresponding reactions with trityl and t-butyl hexafluoroantimonates are unsuccessful.

Aromatic Nitration.

Nitration of azupyrene with AgNO2 gives 4-nitroazupyrene (eq 3).6 In a similar reaction, azulene is converted to 1-nitroazulene (77%).6 Direct substitution of 1,3-dibromoazulene results in the displacement of only one bromine atom to give 1-nitro-3-bromoazulene (eq 4).7

N-Nitrosation.

AgNO2 is a mild reagent for N-demethylation of N,N-dimethyl amines, resulting in N-nitroso-N-methyl amines in moderate yields.8 The reagent is also used for the conversion of imidoyl or sulfonimidoyl chlorides to N-nitroso amides (eq 5).9

AgNO2 as an Adjunct for the Preparation of Other Reagents.

Nitryl Iodide.

This pseudohalogen, prepared by the reaction of AgNO2 with Iodine, adds stereo- and regiospecifically to alkenes to give 1-nitro-2-iodo compounds which, on loss of HI, afford nitroalkenes (eq 6).10

In a similar manner, b-substituted styrenes give trans-b-nitrostyrenes (eq 7).11 Since ring nitration does not occur with this reagent, it offers an advantage over the use of Mercury(II) Chloride/Sodium Nitrite. A reverse addition to alkenes has also been reported.12

The ambident nature of nitryl iodide is also demonstrated in its use as a mild agent for the iodination of alkylbenzenes (eq 8).13

Phenylselenium Nitrite.

This reagent, prepared by the reaction of Benzeneselenenyl Chloride and AgNO2, is useful for the nitroselenation of alkenes14 (eq 9) or conjugated dienes (eq 10).15 Both reactions are catalyzed by HgCl2 which also inhibits nitrite formation. Oxidative deselenation with Hydrogen Peroxide gives nitroalkenes in high yields.

This process has the advantage over nitromercuration in that reactions can be carried out in nonaqueous solvents, thus opening up the procedure to a wider range of alkenes. The reaction with dienes is particularly useful since the reactive 2-nitro-1,3-dienes, formed by oxidative deselenation or by treatment of the nitro selenide with 4-Dimethylaminopyridine,15b can be trapped as the epoxides or reacted in situ with, for example, Ethyl Vinyl Ether to give, after acidification of the intermediate nitronate, unsaturated 1,4-diketones (eq 10).

Thionyl Chloride Nitrite.

This compound, prepared by the reaction of AgNO2 with Thionyl Chloride (1:1), is a mild and selective agent for the preparation of nitrite esters (eq 11).16

Palladium complexes.

AgNO2 has been used in the preparation of Pd complexes for the conversion of terminal alkenes to nitroalkenes17 or as a catalyst18 for the oxidation of terminal alkenes to methyl ketones.

Related Reagents.

Mercury(II) Chloride-Silver(I) Nitrite.


1. Meyer, V.; Stuber, B. CB 1872, 5, 203.
2. (a) Kornblum, N.; Taub, B.; Ungnade, H. E. JACS 1954, 76, 3209. (b) Kornblum, N.; Ungnade, H. E. OSC 1963, 4, 724.
3. Plummer, C. W.; Drake, N. L. JACS 1954, 76, 2720.
4. Wananbe, N.; Uemura, S.; Okano, M. BCJ 1975, 52, 1979.
5. Olah, G. A.; Lin, H. C. S 1975, 537.
6. (a) Anderson, A. G.; Haddock, R. D. New J. Chem. 1992, 16, 919. (b) Anderson, A. G.; Kao, L. G. JOC 1982, 47, 3589.
7. Anderson, A. G.; Harrison, W. F. JACS 1964, 86, 708.
8. Bernardi, L; Bosisio, G. CC 1974, 690.
9. De Carvalho, E.; Norberto, F.; Rosa, E.; Iley, J.; Petel, P. JCR(S) 1985, 132.
10. Hassner, A.; Kropp, J. E.; Kent, G. J. JOC 1969, 34, 2628.
11. Sy, W-W; By, A. W. TL 1985, 26, 1193.
12. Lampture, L. B.; Nayak, U. R. IJC(B) 1980, 19, 1001.
13. Sy, W-W.; Lodge, B. A. TL 1989, 30, 3769.
14. (a) Hayama, T.; Tomoda, S.; Takeuchi, Y.; Nomura, Y. TL 1982, 23, 4733 (b) Hayama, T.; Tomoda, S.; Takeuchi, Y.; Nomura, Y. JOC 1984, 49, 3235.
15. (a) Najera, C.; Yus, M.; Karlsson, U.; Gogoll, A.; Backvall, J-E. TL 1990, 31, 4199. (b) Backvall, J-E.; Karlsson, U; Chinchilla, R. TL 1991, 40, 5607.
16. Hakimelahi, G. H.; Sharghi, H.; Zarrinmayeh, H.; Khalafi-Nezhad, A. HCA 1984, 67, 906.
17. Andrews, M. A.; Chang, T. C-T.; Cheng, C-W. F; Kapustay, L. V.; Kelly, K. P. Z.; Zweifel, M. J. OM 1984, 3, 1479.
18. Sage, J-M.; Gore, J.; Guilmet, E. TL 1989, 30, 6319.

Duncan R. Rae

Organon Laboratories, Motherwell, UK



Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.