(Chief Bee)
05-12-03 15:51
No 432858
(Rated as: excellent)
Rapid Preparation of a Solution of Sodium Hydrogen Sulfide
J Chem Soc 13, 242 (1948)
Previous work on this subject includes that of Stromeyer (Annalen, 1558, 107, 333) who reported that carbon dioxide decomposed a solution of sodium sulfide, and that the latter evolved hydrogen sulfide when treated with sodium hydrogen carbonate, sodium carbonate being formed. No specific details are, however, available for the preparation of sodium hydrogen sulfide by reaction between equivalent amounts of sodium sulfide and sodium hydrogen carbonate, with subsequent use of alcohol to obtain the pure solution of hydrosulfide (cf. Patent GB184795; Patent US1675491). Earlier work by Hodgson and Birtwell on the reduction of 1,3-dinitronapthalene (JCS 1944, 75; J. Soc. Dyers Col., 1945, 61, 171) revealed the necessity for the exclusion of sodium hydroxide and the prevention of a rise in the pH of the reduction medium for maximum reductive efficiency of sodium sulfide. Their reducing agent, however, was generally prepared warm and would lead to deterioration through loss of hydrogen sulfide. Later, Hodgson and Hathway (JCS 1945, 123) showed that sodium hydrogen carbonate could not be efficiently replaced by sodium carbonate in Hodgson and Birtwell's experiments, and that carbon dioxide was not evolved when an aqueous solution containing equivalent amounts of sodium hydrogen carbolate and sodium sulfide was heated. Finally, Hodgson and Ward (JCS 1945, 590, 663, 794) found that the reductive efficiency of the above mixture was superior to that of sodium hydrogen sulfide prepared by treating sodium hydroxide with hydrogen sulfide, or by the addition of hydrochloric acid to a solution of sodium sulfide (cf. Lapworth and Pearson, JCS 1321, 119, 765 ; Lapworth and Haworth, JCS 1321, 119, 768), in which much hydrogen sulfide is lost even by working in a tall cylinder at 0°C.
A method is now described, whereby a comparatively concentrated solution of almost pure sodium hydrogen sulfide (96-98% of the calculated amount of NaSH) in aqueous methanol or ethanol can be rapidly prepared which contains only a negligible amount of sodium carbonate. Almost all the sodium carbonate formed by the reaction of the sodium sulfide and sodium hydrogen carbonate in aqueous methanol is precipitated as the crystalline monohydrate with a smell amount of "occluded" sulfide.
Other reagents such as boric acid, sodium hydrogen phosphate, oxalic acid, tartaric acid, and sodium hydrogen sulfate are unsuitable. Ethanol is nearly as efficient as methanol but acetone is unsuitable.
When an aqueous solution of sodium sulfide is treated with solid sodium hydrogen carbonate, precipitation of sodium carbonate decahydrate slowly takes place, but this is far from complete even after long standing at 15°C.
Similar methods cannot be used to prepare pure aqueous alcoholic potassium hydrogen sulfide, owing to the much greater solubility of potassiurn carbonate in methanol or ethanol, and the alternative reactants above also proved unsuitable.
Experimental
A concentrated aqueous solution of sodium sulfide is prepared by dissolution of the pure ("AnalaR") nonahydrate (~95% Na2S*9H2O) in freshly distilled water, and then diluted to contain 13% Na2S w/v. Finely powdered sodium hydrogen carbonate (14 g, 99.8% purity) is then stirred into the above solution (100 mL) below 20°C; it dissolves at once with evolution of heat. Methyl alcohol (100 mL) is next added with stirring, also below 20°C; there is further evolution of heat, and almost complete precipitation of crystalline sodium carbonate occurs immediately. After 30 minutes, the mixture is filtered at the pump, and the residue washed portion-,vise with methyl alcohol (50 mL). The filtrate now contains sodium hydrogen sulfide (~9 g) and a little sodium carbonate (~0.6 g), the respective concentrations being ca. 3.5 g and 0.2 g per 100 mL of solution.
(a) For ordinary purposes, it is sufficient to dissolve equivalent amounts of sodium sulfide nonahydrate and sodium hydrogen carbonate in the required amount of water, add the necessary volume of methyl alcohol and filter off the precipitated sodium carbonate; the filtrate can then be used forthwith for reduction.
(b) When more concentrated solutions of sodium sulfide are employed, the precipitated sodium carbonate contains "occluded" sulfide.
(c) The solution of sodium hydrogen sulfide, which is only faintly alkaline to phenolphthalein, can be kept in a stoppered bottle for at least a week with but slight deterioration.
(Hive Bee)
05-13-03 13:13
No 432986
This is great Rhodium, thanks!
When investigating a preparation for methanethiol, SWIM saw NaSH can also be made by bubbling a NaOH solution with H2S, but who wants to deal with H2S!? Not sure what else NaSH is used for at The Hive, but SWIM is really interested in using it for beta alkylthio substitutions (analogous to pihkal #13 BOB).
Edit: Oops, SWIM was so excited, didn't read the abstract very carefully. Stating the obvious, this NaOH'less preparation can be useful in Antoncho's nitro--> hydroxy proposals.
(Hive Bee)
05-13-03 13:52
No 432993
I think it is possible to synth thiols from thiourea (like in the modafinil synth) from alkyl-bromide
Can you post your synth with sulfur? I am interested in thiols for 2C-T-X synth.
Beware methanethiol is a gas, better to store it in its dissulfur form.
(Hive Bee)
05-13-03 14:17
No 432998
From 4-Br-2,5-DMB, one can react with thiourea and NaOH (important!!) to give the thiol compound. You can then ethylate or propylate to give the ethyl or propyl sulphide compound. Japanese Patent 63203632 uses an acetic acid solvent, but SWIM has a reference stating that DMSO is the preferred solvent(99% yield). Will post if you're interested. Ethanol will also work, but gives low yields, and is smelly. This should also work with 5-bromovanillin to give 3-TM, 3-TE, or 3-TME in pihkal. Suprizingly, bees at The Hive haven't shown much interest towards thiol compounds, but SWIM absolutely loves them!
But SWIM wasn't talking about this. SWIM was talking about beta-substitutions on the styrene chain, as in Patent GB793965. Methanethiol's danger is comparable to that of H2S.
Methanethiol is prepared by reacting a solution of NaSH with, guess what, sodium methyl sulphate. The solution is refluxed, and from the top of the condensor the methanethiol will gas off (b.p. ~6C). The gas is directed into a solution of nitrostyrene as in the british patent. SWIM bets the piperidine can be replaced with another strong base like methylamine.
Maybe a new thread should be started to talk about these ideas? SWIM is glad someone else is interesting in the 2C-T's
.[red]Edit by Rhodium: The japanese paper above is available translated at ../rhodium /thiophe
(Chief Bee)
05-13-03 14:33
No 433002
Yes, I am certainly interested in that DMSO ref, post it in a new thread and let us continue the discussion there.