カルシウム シアナミド

外観

うすい灰色～褐色～黒色粉末～結晶

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

効能

抗酒癖薬, アルコール増感薬

化学的特性

Calcium cyanamide is a blackish-gray, shiny crystalline material or powder.

物理的性質

Pure product is a colorless, hexagonal crystal or white powder. Commercial grade material may be grayish-black powder or lump (the color is due to presence of calcium carbide and other impurities); density 2.29 g/cm³; melts around 1,340°C; sublimes around 1,150 to 1,200°C on rapid heating; reacts with water.

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.

調製方法

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.

定義

calcium cyanamide: A colourlesssolid, CaCN2, which sublimes at1300°C. It is prepared by heating calciumdicarbide at 800°C in a streamof nitrogen:
CaC_2(s) + N_2(g) → CaCN_2(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:
CaCN_2(s) + 3H₂O_(l) → CaCO_3(s) +2NH_3(g)
It is also used in the production ofmelamine, urea, and certain cyanidesalts.

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)

工業製造

炭酸カルシウムまたは酸化カルシウムに、600～850℃でアンモニアと一酸化炭素とを反応させると得られる。工業的には、細粒ないし粉末状の炭化カルシウムを、窒素気流中で約1000℃で加熱する方法がとられる。

CaC2＋N2―→CaCN2＋C

この場合は黒鉛状の微粉末炭素を副生するので、生成物は黒色を呈する。この混合物を石灰窒素という。純粋なものは無色の固体。水に溶け徐々に加水分解されてアンモニアと炭酸カルシウムとになる。

CaCN2＋3H2O―→2NH3＋CaCO3

加熱によりこの分解は促進される。強アルカリ水溶液と反応して尿素を生成し、高温では炭素と作用してシアン化カルシウムを生ずる。

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.

空気と水の反応

Depending on the calcium carbide content, the cyanamide reacts with water (moisture from air or soil) to produce acetylene and hydrated calcium oxide or calcium hydroxide. Absorption of water during handling or storage of technical calcium cyanamide may cause explosion [Pieri, M. Chem. Abs. 46, 8335 1952].

反応プロフィール

When hydrated CALCIUM CARBIDE generates salts of calcium that are basic and are generally soluble in water. The resulting solutions contain moderate concentrations of hydroxide ions and have pH's greater than 7.0. They react as bases to neutralize acids. These neutralizations generate heat, but less or far less than is generated by neutralization of the bases in reactivity group 10 (Bases) and the neutralization of amines. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible.

危険性

Fire risk with moisture or combined with calcium carbide. Skin, eye, and upper respiratory tract irritant. Questionable carcinogen.

健康ハザード

Inhalation or contact with vapors, substance or decomposition products may cause severe injury or death. May produce corrosive solutions on contact with water. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.

火災危険

Produce flammable gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Runoff may create fire or explosion hazard.

安全性プロファイル

Poison by ingestion, inhalation, sh contact, intravenous, and intraperitoneal routes. Moderately toxic to humans by ingestion. Questionable carcinogen with experimental tumorigenic data. Mutation data reported. The fatal dose, by ingestion, is probably around 20 to 30 g for an adult. It does not have a cyanide effect. Calcium cyanamide is not believed to have a cumulative action. Flammable. Reaction with water forms the explosive acetylene gas. When heated to decomposition it emits toxic fumes of NOx and CN-. See also CALCIUM COMPOUNDS, AMIDES, and CYANIDE

職業ばく露

Calcium cyanamide is used in agriculture as a fertilizer, herbicide; defoliant for cotton plants; and pesticide. It is also used in the manufacture of dicyandiamide and calcium cyanide as a desulfurizer in the iron and steel industry; and in steel hardening.

発がん性

Calcium cyanamide was weakly mutagenic in Salmonella typhimurium strain TA1535 and nonmutagenic in strain TA100.

輸送方法

UN1403 Calcium cyanamide with .1% calcium carbide, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material

不和合性

Commercial grades of calcium cyanamide may contain calcium carbide; contact with any form of moisture solutions may cause decomposition, liberating explosive acetylene gas and ammonia. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. May polymerize in water or alkaline solutions to dicyanamide. Contact with all solvents tested also causes decomposition