4080
J. Chem. Eng. Data 2010, 55, 4080–4081
Solubility of Sodium Sulfide in Alcohols
Alexander V. Kurzin,* Andrey N. Evdokimov, Valerija S. Golikova, and Olesja S. Pavlova
Organic Chemistry Department, Faculty of Chemical Technology, Saint Petersburg State Technological University of Plant
Polymers (SPSTUPP-SPbGTURP), 4, Ivana Chernykh, Saint Petersburg 198095, Russia
The solubility of sodium sulfide in methanol, ethanol, 2-propanol, 2-methyl-1-propanol, and benzyl alcohol
and the acid-base interaction of these compounds have been determined at (20 and 35) °C. The reactions
result in the formation of sodium alkoxide and hydrosulfide. The reported values on the solubility of sodium
sulfide in alcohols differ essentially from the data described in the literature.
The resulting solution contained 4.2 parts of sodium methoxide,
1.9 parts of sodium hydrosulfide, 15.6 parts of sodium sulfide,
and 78.3 parts of CH3OH. The solid NaHS (2.5 parts)
precipitated from a reaction mixture was filtered out. The
remaining sodium hydrosulfide and sulfide were separated by
evaporating methanol from the solution and then were readily
filtered from the sodium methoxide solution.5
In the present paper, the solubility of anhydrous Na2S in
methanol, ethanol, 2-propanol, 2-methyl-1-propanol, and benzyl
alcohol has been determined at (20 and 35) °C in view of the
above interaction. In addition, the distribution of all components
in the Na2S + ROH reaction systems was investigated under
the conditions of phase and chemical equilibrium.
Introduction
Sodium sulfide is used in different branches of chemical
technology, for example, pulp and paper, textile, tanning
industry, and metallurgy, and as a strong reducing agent in
organic synthesis.1,2 Therefore, physical and chemical properties
of solutions of this salt are important, especially solubility data
in alcohols which are used in the process of pure anhydrous
sodium sulfide production.1-3 No data on solubility of alkali
metal sulfides in methanol as well as in other alcohols were
found in the most popular reference books and databases. Both
vapor-liquid equilibrium and solubility data for the ternary
systems containing alkali metal sulfides and mixed solvents are
also absent in the literature. Beyer3 presented the information
about the solubility of anhydrous sodium sulfide and Na2S·9H2O
in alcohols. These published data on solubility of sodium sulfide
at 20 °C in methanol, ethanol, isobutanol, benzyl alcohol, and
ethylene glycol are listed in Table 1.
Experimental Section
Reagents. Anhydrous chemicals were used as much as
possible. All alcohols (w g 99.9 %, Merck, Sigma-Aldrich, and
Vekton) were dehydrated and stored over molecular sieves of
type 3A. The water mass fraction in alcohols was determined
by the Karl Fischer coulometric method, and it did not exceed
0.01 %. Sodium sulfide was dehydrated, dried in a vacuum oven,
and purified from Na2S·9H2O (w g 34.5 %, Reaktiv-SP) as
described by Beyer.3
Procedure. The equilibrium concentrations of the components
of Na2S + ROH reaction systems were determined using the
titrimetric method.7 For this purpose, the mixtures of known
masses of sulfide and alcohol were prepared gravimetrically
using an analytical balance with an uncertainty of 0.1 mg and
continuously agitated within 10 h in a temperature-controlled
cell at either (20 or 35) °C. The uncertainty of the measured
temperature by a mercury-in-glass thermometer was 0.1 °C.
Then the suspension was passed through a porous glass filter
under pressure. The filter was held at the target temperature.
The solid and liquid phases were analyzed separately. The
However, the author3 did not take into account the possible
reaction between sulfide of alkali metal as the base and alcohol
as the acid (eq 1)
M2S + ROH ) MHS + ROM
(1)
where M is an alkali metal and R is an alkyl group.
It is known4-6 that alcoholysis of some alkali metal com-
pounds: salts (carbonates, cyanides, sulfides, orthophosphates),
amides, azides, nitrides, alkali, hydrides, and acetylenides, can
be considered as a method for alkoxide production (eqs 2, 3,
and 4)
MX + ROH ) HX + ROM
M2X + ROH ) MHX + ROM
(2)
(3)
M3X + ROH ) M2HX + ROM
(4)
where M is an alkali metal; R is an alkyl group; X ) OH, NH2,
H, N3, CN, Ct C (eq 2), S, CO3 (eq 3), and PO4 (eq 4).
Moreover, an acid-base interaction according to eq 1 may
be used for the production of anhydrous sodium and potassium
hydrosulfides which are applied for the synthesis of thiols
(mercaptans). Loder and Lee5 reported the formation and the
recovery of alkoxides according to eq 1 at the temperature range
(60 to 70) °C for the first time. They offered the process for
the preparation of sodium methoxide wherein 21.7 parts of
anhydrous Na2S and 78.3 parts of CH3OH reacted at 62 °C.
Table 1. Published Dataa on Solubility s of Anhydrous Sodium
Sulfide in Alcohols and Ethylene Glycol at 20 °C
s
solvent
methanol
ethanol
g ·L-1
160
90
isobutanol
31
benzyl alcohol
ethylene glycol
>40
>200
* To whom correspondence should be addressed. E-mail: zakora@mail.ru.
a Ref 3.
10.1021/je100276c 2010 American Chemical Society
Published on Web 06/09/2010
Kurzin, Alexander V.
