Sodium Hydrogen Sulfide


[16721-80-5]  · HNaS  · Sodium Hydrogen Sulfide  · (MW 56.07) (hydrate)


(a nucleophile and reducing agent derived from H2S; a reagent for the synthesis of thiols1 and other divalent sulfur compounds,2 including thiocarbonyl derivatives;3 reduces aromatic nitro groups to amines4)

Physical Data: mp (hydrate) 52-54 °C; anhyd, 350 °C; d 1.79 g cm-3; pKa (HS- &ibond; S2- + H+) 14.15.

Solubility: v sol H2O; sol EtOH, DMF (colored solution).

Form Supplied in: yellow chips (NaSH.xH2O, may be principally NaSH.2H2O); also available anhydrous; may contain Na2S, Na2S2O3 Na2CO3.

Analysis of Reagent Purity: iodometric titration.5

Preparative Methods: saturation of ethanolic Sodium Hydroxide with Hydrogen Sulfide;5 anhydrous NaSH is obtained by precipitation with ether. Saturation with H2S shifts the equilibrium, 2NaSH &ibond; Na2S + H2S, to the left, as does operation in a solvent less polar than water or addition of NaHCO3 to Na2S.

Handling, Storage, and Precautions: store in cool, dry place under nitrogen. Exposure to air forms Na2S2O4 and Na2CO3; very hygroscopic. Flammable; produces SO2 on combustion. Stench. A reducing agent. Incompatible with acids (produces H2S), with strong oxidizing agents, and with Zn, Al, and Cu. Corrosive (NaSH + H2O &ibond; NaOH + H2S). Use in a well-ventilated fume hood. Toxicity like that of Na2S. Extremely destructive to mucous membranes, eyes, upper respiratory tract, and skin. Can cause blindness; inhalation can be fatal. Decontamination with FeCl3 (production of insoluble iron sulfides).


Treatment of halides, sulfonate esters, epoxides (eq 1),6a and aziridines with NaSH yields thiols. Saturation with H2S helps to prevent sulfide formation. Near quantitative yields of thiols are obtained from primary alkyl bromides in DMSO.6b Primary substrates are best; tertiary substrates undergo elimination reactions. Aliphatic thiols are readily desulfurized by Raney Nickel, thus providing a method for reduction of alcohols to alkanes (eq 2).7 Activated aromatic or heteroaromatic halides (eq 3)8 also are satisfactory, but nitro groups and cyano groups are likely to be incompatible due to reduction (or substitution) and addition reactions, respectively. Michael additions of SH- to activated double and triple bonds also yield thiols or thiolates; sulfides may be obtained by further reaction of the thiolate (eq 4).9 Thiol acids (RCOSH) are obtained from NaSH and acid chlorides or anhydrides (eq 5).10

Thioethers (Sulfides).2

Sodium sulfide and sodium thiolates are more commonly used to prepare thioethers (eq 4), but NaSH has been applied to the synthesis of heterocyclic compounds of sulfur. Both the facile addition of NaSH to alkynic bonds9a,11 and its desilylating ability are exemplified in eq 6.11a The addition of NaSH in liquid NH3 to phenylacetylene gave both (Z,Z)- and (E,Z)-distyryl sulfide (in a ratio of 2.5:1), unlike Na2S.9H2O which gave principally the (Z,Z) isomer (ratio 20:1).11d

Thiocarbonyl Compounds.3

Addition of NaSH to iminium salts (Vilsmeier intermediates) (eq 7)12 and related compounds13 results in introduction of the thiocarbonyl group. Thioamides are obtained by addition to the triple bond of nitriles.


Aromatic, but not aliphatic, nitro groups are reduced by NaSH to amino groups,4,14 often selectively,15 as shown in eq 8. Favorable steric factors and the presence of an ortho phenolic hydroxyl group facilitate the reduction of one nitro group in preference to others. Further reductions are the dehalogenation of a-halo ketones and a-halo esters mediated by Tin(II) Chloride16 and the conversion of ArN=NAr to ArNH217 (a nitro group is reduced preferentially18).


Anti debromination of gem-dibromides by NaSH (or Na2S) yields alkenes (eq 9).19 2-Pyranthiones are isomerized to 2-thiopyrones by NaSH.20 A solution of NaSH at pH 8 selectively removes the acetyl group from menthyl O-acetylmandelate.21

Related Reagents.

Potassium Hydrogen Sulfide; Sodium Sulfide; Sodium Telluride.

1. Gundermann, K.-D.; Hümke, K. MOC 1985, E11, 32.
2. Gundermann, K.-D.; Hümke, K. MOC 1985, E11, 158.
3. (a) Voss, J. MOC 1985, E11, 188. (b) Schaumann, E. The Chemistry of Double Bond Functional Groups, Supplement A; Patai, S. Ed; Wiley: New York, 1989; Vol. 2, Part 2, pp 1269-1367. (c) Mayer, R.; Scheithauer, S. MOC 1985, E5, 785. (d) Mayer, R.; Scheithauer, S. MOC 1985, E5, 891. (e) Bauer, W.; Kühlein, K. MOC 1985, E5, 1218.
4. Porter, H. K. OR 1973, 20, 455.
5. Eibeck, R. E. Inorg. Synth. 1963, 7, 128.
6. (a) Goodman, L.; Benitez, A.; Baker, B. R. JACS 1958, 80, 1680. (b) Vasil'tsov, A. M.; Trofimov, B. A.; Amosova, S. V. JOU 1983, 19, 1197.
7. Dreiding, A. S.; Tomasewski, A. J. JACS 1955, 77, 411.
8. Shaw, E.; Bernstein, J.; Losee, K.; Lott, W. A. JACS 1950, 72, 4362.
9. (a) Haefliger, W.; Petrzilka, T. HCA 1966, 49, 1937. (b) Emr, A.; Roubinek, F. CCC 1956, 21, 1651.
10. Gottstein, W. J.; Babel, R. B.; Crast, L. B.; Essery, J. M.; Fraser, R. R.; Godfrey, J. C.; Holdrege, C. T.; Minor, W. F.; Neubert, M. E.; Panetta, C. A.; Cheney, L. C. JMC 1965, 8, 794.
11. (a) Detty, M. R.; Luss, H. R. OM 1992, 11, 2157. (b) Lucchesini, F.; Picci, N.; Pocci, M.; DeMunno, A.; Bertini, V. H 1989, 29, 97. (c) Trofimov, B. A.; Amosova, S. V.; Musorin, G. K.; Voronkov, M. G. JOU 1978, 14, 618. (d) Takikawa, Y.; Shimada, K.; Matsumoto, H.; Tanabe, H.; Takizawa, S. CL 1983, 1351.
12. (a) Muraoka, M.; Yamamoto, T.; Enomoto, K.; Takeshima, T. JCS(P1) 1989, 1241. (b) McKenzie, S.; Reid, D. H. JCS(C) 1970, 145. (c) Dolenko, E. V.; Usov, V. A.; Timokhina, L. V.; Usova, T. L.; Protasova, L. E.; Voronkov, M. G. Chem. Heterocycl. Compd. 1987, 23, 1365.
13. (a) Kaloustian, M. K.; Khouri, F. TL 1981, 22, 413. (b) Bodine, J. J.; Kaloustian, M. K. SC 1982, 12, 787. (c) Nader, R. B.; Kaloustian, M. K. TL 1979, 1477. (d) Kung, P.-P.; Jones, R. A. TL 1991, 32, 3919.
14. Campaigne, E.; Budde, W. M.; Schaefer, G. F. OSC 1963, 4, 31.
15. (a) Idoux, J. P. JCS(C) 1970, 435. (b) Matveev, L. G.; Sushetskaya, T. M.; Abramov, I. A.; Geletii, Y. G.; Trentovskaya, L. K. Khim. Prom-st. (Moscow) 1984, 143 (CA 1984, 101, 54 640f). (c) Hodgson, H. H.; Ward, E. R. JCS 1948, 242; 1945, 794.
16. Ono, A.; Maruyama, T.; Kamimura, J. S 1987, 1093.
17. Israel, M.; Protopapa, H. K.; Chatterjee, S.; Modest, E. J. JPS 1965, 54, 1626.
18. (a) Ueno, K. JACS 1952, 74, 4508. (b) Atkinson, C. M.; Brown, C. W.; McIntyre, J.; Simpson, J. C. E. JCS 1954, 2023.
19. (a) Nakayama, J.; Machida, H.; Hoshino, M. TL 1983, 24, 3001. (b) Doshi, A. G.; Ghiya, B. J. JIC 1986, 63, 404.
20. Hoederath, W.; Hartke, K. AP 1984, 317, 938.
21. Whitesell, J. K.; Reynolds, D. JOC 1983, 48, 3548.

Donald C. Dittmer

Syracuse University, NY, USA

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