Calcium Cyanamide

Japanese: カルシウムシアナミド

CaCN ₂ (80.10). It is obtained by igniting calcium carbide, CaC _2, in N _2. This reaction was the first example of nitrogen fixation in air. The pure form is a colorless crystal. It has a hexagonal crystal system with Ca ²⁺ and linear [NCN] ^2- arranged in a distorted NaCl-type lattice. NC 1.22 Å. Melting point is about 1340 °C. It sublimes at 1150-1200 °C. Density is 2.29 g cm ^-3 . It reacts with cold water to give NH ₃ and CaCO ₃ , and with hot water to give dicyandiamide (NCNH ₂ ) _2. It reacts with strong aqueous alkali to give urea. Lime nitrogen (gray powder) is a mixture of CaCN ₂ and C. It is used as a basal fertilizer for nitrogen fertilizer (it reacts with moisture in the soil to become dicyandiamide, which then becomes urea and ammonium carbonate over a few weeks, acting as a nitrogen fertilizer). However, this dicyandiamide is harmful to plants, and is unsuitable for use as a top dressing where a fast effect is required. On the other hand, taking advantage of the toxicity of dicyandiamide, it is also used for weed control, sterilization, and disinfection. It is also used as a raw material for the synthesis of dicyandiamide and melamine, and for hardening steel. [CAS 156-62-7]

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

Japanese:

CaCN₂(80.10)．炭化カルシウムCaC₂を N₂ 中で強熱すると得られる．この反応は，空気中の窒素固定反応の最初の例である．純粋なものは無色の結晶．六方晶系で，ひずんだNaCl型の格子に，Ca^2＋と直線形の [N-C-N]^2－とが配列されている．N-C 1.22 Å．融点約1340 ℃．1150～1200 ℃ で昇華する．密度2.29 g cm^－3．冷水と反応してNH₃とCaCO₃になり，熱水と反応してジシアンジアミド (NCNH₂)₂ になる．強アルカリ水溶液と反応して尿素を生じる．石灰窒素(灰色の粉末)は，CaCN₂とCの混合物である．窒素肥料として，基肥に用いられる(土中で水分と反応して，まずジシアンジアミドとなり，数週間でさらに尿素と炭酸アンモニウムとになり，窒素肥料としてはたらく)．しかし，このジシアンジアミドは植物に有害であり，速効が求められる追肥などには不適当である．一方，このジシアンジアミドの毒性を利用して，除草，殺菌，消毒などにも用いられる．そのほか，ジシアンジアミドやメラミンの合成原料，鋼の焼入れなどに用いられる．[CAS 156-62-7]