硫化ナトリウム

化学的特性Sodium sulfide,Na2S, also known as sodium sulfuret,is an irritating, water-soluble, yellowish to reddish, deliquescent powder that melts at 1180°C (2156 °F). Sodium sulfide is used as a chemical intermediate and solvent,in conversion of wood into paper pulp, as a photographic and analytical reagent,as a source of sulfide,as a reducing agent,in organic reactions, as a depilatory, and in sheep dips.

解説無水物は無色の立方晶系．密度1.86 g cm－3．融点950 ℃．空気中で酸化されてチオ硫酸ナトリウムを生じ，また水分と二酸化炭素を吸収して炭酸ナトリウムと硫化水素を生じる．九水和物は無色の正方晶系柱状晶．密度1.43 g cm－3．50 ℃ で融解し，強熱すると分解する．潮解性で，無水物，水和物ともに水によく溶け，強アルカリ性を示し，酸に溶けて硫化水素を発生する(二酸化炭素を含む水(炭酸水)によっても分解される)．エタノールに難溶，エーテルに不溶．硫黄を溶解して多硫化ナトリウム(Na2Sn，n ＝ 2，3，4，5)を生じる．

用途PPS樹脂原料、有機合成化学用皮革脱毛剤、硫化染色助剤、硫化染料原料、化繊脱硫。

使用These yellow flakes were made by fusing sodium carbonate with sulfur. Soluble in water but less so in alcohol, sodium sulfide was lovingly called “stink” by those who used it for toning prints or intensifying negatives because of its sulfurous smell.

一般的な説明Sodium sulfide is a yellow to brick red crystalline mass or fused solid with an odor of rotten eggs. If exposed to moist air Sodium sulfide is liable to spontaneous heating and may cause ignition of nearby combustible material. Sodium sulfide absorbs moisture from the air.

使用用途硫化ナトリウムは、医薬品、食品添加物、工業用、試薬など、幅広く利用されています。 工業用途の具体例として、ビスコース人絹、皮革の脱毛、スフの脱硫用、硫化染色助剤、PPS樹脂原料、有機硫化物の製造原料、の浮遊選鉱剤、排水中の重金属の除去などが挙げられます。また、やパルプの製造にも利用可能です。さらに、乾燥剤や浴用剤のような、身近な製品にも使用されています。 医薬品用途では、主にフェナセチンなどの解熱剤の製造に用いられます。

製造方法Sodium sulfide is prepared by heating sodium bisulfate with sodium chloride and coal above 950°C. The product mixture is extracted with water and the hydrated sulfide is obtained from the solution by crystallization: NaHSO4 + NaCl + 2C → Na2S + 2CO2↑ + HCl↑Sodium sulfide also is produced from its elements in liquid ammonia: Na + 2S → Na2S.

純化方法Some purification of the hydrated salt can be achieved by selecting large crystals and removing the surface layer (contaminated with oxidation products) by washing with distilled water. Other metal ions can be removed from Na2S solutions by passage through a column of Dowex ion-exchange A-1 resin, Na+-form. The hydrated salt can be rendered anhydrous by heating it in a stream of H2 or N2 until water is no longer evolved. (The resulting cake should not be heated to fusion because it is readily oxidised.) Recrystallise it from distilled water [Anderson & Azowlay J Chem Soc, Dalton Trans 469 1986]. Note that sodium sulfide hydrolyses in H2O to form NaHS + H2O, and is therefore alkaline. A 0.1N solution in H2O is 86% hydrolysed at room temperature. Its solubility in H2O is 8% at 0o, 12% at 20o and 30% at 50o. The anhydrous salt is obtained by allowing it to stand in a vacuum over conc H2SO4 or P2O5 at 45o to start with, then at 30-35o when the salt contains 4% of water. The last traces of water are removed by heating to 700o in a glass or porcelain tube in a stream of H2 to give pure H2S. [Fehér in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I pp 358-360 1963.]