カルシウム シアナミド

解説カルシウムシアナミド，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，Ca2＋ 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．

用途肥料、有機合成原料

使用Calcium Cyanamide is used as a fertilizer, herbicide, insecticide, a steel-making additive and an ore processing material. It can also be used to make thiourea, guanidine and ferrocyanides. manufacture of calcium cyanide, melamine, dicyandiamide.

一般的な説明A colorless to gray, odorless solid. May cause illness from ingestion. May irritate the skin. If exposed to water or high temperatures, calcium cyanamide may generate toxic and flammable fumes. Used to make pesticides and in fertilizers.

Calcium cyanamide was first produced commercially around 1900 as a fertilizer. The process of making calcium cyanamide involves three raw materials—coke, coal, and limestone— plus nitrogen. The limestone (calcium carbonate) is burned with coal to produce calcium oxide. The calcium oxide is then allowed to react with amorphous carbon in the furnace at 2000°C with the formation of calcium carbide (CaC2). Finely powdered calcium carbide is heated to 1000°C in an electric furnace into which pure nitrogen is passed. It is then removed and uncombined calcium carbide removed by leaching.

製造方法Calcium cyanamide is prepared from calcium carbide. The carbide powder is heated at about 1,000°C in an electric furnace into which nitrogen is passed for several hours. The product is cooled to ambient temperatures and any unreacted carbide is leached out cautiously with water. CaC2 + N2 → CaCN2 + C (ΔHƒ°= –69.0 kcal/mol at 25°C)

定義calcium cyanamide: A colourlesssolid, CaCN2, which sublimes at1300°C. It is prepared by heating calciumdicarbide at 800°C in a streamof nitrogen:CaC2(s) + N2(g) → CaCN2(s) + C(s)The reaction has been used as amethod of fixing nitrogen in countriesin which cheap electricity isavailable to make the calcium dicarbide(the cyanamide process). Calciumcyanamide can be used as afertilizer because it reacts with waterto give ammonia and calcium carbonate:CaCN2(s) + 3H2O(l) → CaCO3(s) +2NH3(g)It is also used in the production ofmelamine, urea, and certain cyanidesalts.