Calcium Carbide - Tanka Calcium

CaC ₂ (69.10). Its IUPAC name is calcium dicarbide(2-). Its common industrial name is carbide. It is made by heating coke and quicklime in an electric furnace to over 2000 °C. It has four transformations. At room temperature it is tetragonal, and at 450 °C it transforms to a cubic system. It is a colorless crystal. However, industrial products are black-gray lumps due to impurities (carbon, etc.). ^{Ca 2+} and C≡C ^2- form rock-salt crystals, but C≡C ^2- is not spherically symmetric like ^Cl- , so it is distorted. Density 2.22 g cm ^-3 (18 °C). Ca-C 2.60, 2.81 Å, CC 1.19 Å. Melting point 2300 °C. It reacts with water to produce acetylene. It is stable at room temperature in dry air, but oxidizes above 350 °C. It reacts with N ₂ above 600 °C to form calcium cyanamide (CaCN ₂₎ . It is reducing at high temperatures and reduces many oxides, for example, CuS, CuO to Cu. Its main uses are as a raw material for calcium carbonate fertilizer, and for small-scale acetylene generation (in laboratories, outdoors, etc.). In the past, acetylene was produced from calcium carbide in the Reppe reaction to synthesize various organic compounds, but this has now been replaced by a petrochemical product. It is also used as a reducing agent in metal manufacturing. It is designated as a Class 3 hazardous material, a spontaneously combustible substance, and a water-inhibiting substance under the Fire Service Act. [CAS 75-20-7]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

CaC₂(69.10)．IUPAC組成方式名称は二炭化(2－)カルシウム(calcium dicarbide(2－))．工業製品名としての通俗名はカーバイド．コークスと生石灰を，電気炉で2000 ℃ 以上に加熱してつくる．4種類の変態がある．常温では正方晶系，450 ℃ で立方晶系に転移する．無色の結晶．ただし，工業製品は不純物(炭素など)のため，黒灰色の塊．Ca^2＋ とC≡ C^2－が岩塩型構造の結晶をつくるが，C≡ C^2－は Cl^－ のように球対称でないため，ひずんでいる．密度2.22 g cm^－3(18 ℃)．Ca-C 2.60，2.81 Å，C-C 1.19 Å．融点2300 ℃．水と反応してアセチレンを発生する．乾燥空気中では室温では安定であるが，350 ℃ 以上では酸化される．N₂ と600 ℃ 以上で反応してカルシウムシアナミドCaCN₂となる．高温では還元性で，多くの酸化物などを還元する．たとえば，CuS，CuO→Cu．おもな用途は石灰窒素肥料の原料，そのほか小規模アセチレン発生用(実験室・野外など)．以前はレッペ反応で各種の有機化合物を合成するためのアセチレンを炭化カルシウムからつくったが，現在は石油化学製品にかわった．金属製造用の還元剤にも用いられる．消防法第3類危険物・自然発火性物質及び禁水性物質指定．[CAS 75-20-7]

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報