Cyanamide

• Alzodef
• Amidocyanogen
• Carbamidsäurenitril
• Carbamonitril
• Carbodiimide
• Cyanogenamid
• Cyansäureamid
• Defolup
• Hydrogen cyanamide
• Karbamonnitril
• Carbodiimide

Colorless, hygroscopic solid

Fixed

1.28 g · cm -3

44 ° C.

260 ° C ( decomposition)

0.5 Pa ( 20 ° C)

Readily soluble in water, ethanol and diethyl ether, and many polar organic solvents

1.4418 (48 ° C)

Risk

1 mg · m-3

125 mg · kg -1 ( LD50, rat, oral)

58.8 kJ / mol

Template: Infobox chemical / molecular formula search available

Cyanamid is the amide of cyanic acid. It can also be interpreted as a nitrile of the carbamic acid and its equilibrium shape carbodiimide as diimide of carbon dioxide.

Production and representation

Cyanamide can be obtained by hydrolysis of the shown in the Frank - Caro process Calciumcyanamids (also cyanamide ) in the presence of carbon dioxide:

Leaving cyanogen chloride react with ammonia, then also formed cyanamide, which is in equilibrium with carbodiimide.

Properties

Cyanamid is a colorless and odorless, crystalline, hygroscopic substance with fairly high reactivity, the polymerized part explosively when heated. The toxic substance is flammable and highly soluble in water (850 g · l-1 at 25 ° C) and organic solvents. The commercial form as a blue colored 50 % aqueous solution of an acid reaction ( pH 3.5-4.2 at concentrations of 560 g · l-1 at 20 ° C).

Use

Since the mid-1960s, there are methods to stabilize Cyanamid and to make available on an industrial scale. Because of the strong tendency to self- condensation (dimer: dicyandiamide, trimer: melamine) in an alkaline medium cyanamide are stabilized by adding 0.5 % by weight of NaH2PO4 phosphate buffer. Sturdy solid cyanamide is produced by gentle evaporation of a stabilized cyanamide and subsequent addition of a hydrolysis- formic acid ester, the traces of moisture absorbed ( suppression of urea formation ), traces of alkali (ammonia) and neutralized continuously small amounts of formic acid releases.

Cyanamide is used in agriculture as a fertilizer and as a plant growth regulator by lifting the dormancy of fruit plants ( table grapes, kiwis, apples, pears) (English dormancy breaking agent ). The 50% aqueous solution is also particularly used as a biocide ( disinfectant) in the pig, as it effectively kills salmonella and schigella and combat flying in all stages of development.

In the chemical industry cyanamide as a versatile starting material, eg for the production of herbicides, synthetic resins needed (curing of epoxides ) and as a bleach activator for hydrogen peroxide at alkaline pH in detergents and chlorine-free pulp bleaching. The majority of the cyanamide is immediately converted to Cyanoguanidine and further processed.

Cyanamide can be regarded as a functional Einkohlenstofffragment which may react as an electrophile or nucleophile. A convenient method for the preparation of secondary amines which are not contaminated with primary or tertiary amines, the reaction of cyanamide with alkyl halides to give N, N- dialkylcyanamides that are easily hydrolyzed and decarboxylated to dialkyl amines. Cyanamide is added in the presence of N-bromosuccinimide NBS to olefinic double bonds. The addition product is converted by base in N- Cyanaziridine, cyclized in the presence of acids to imidazolines, from vicinal diamines which can be represented by alkaline cleavage.

Cyanamide is also suitable as versatile synthetic building block for Heterocycles: from 1,2 -diaminobenzene (o- phenylenediamine ) is formed 2- amino benzimidazole, with the easily accessible cyclic enamine 4 - (1- cyclohexenyl ) morpholine and elemental sulfur is a 2 -aminothiazole in good yields. Of cyanamide and sodium dicyanamide cyanogen chloride is available in good yield and high purity which is suitable as an intermediate for synthesis of pharmaceutical active ingredients.

In the industrial synthesis of the essential for muscle, nerve and brain function of creatine guanidino group is introduced by reaction of cyanamide with sarcosine.

This synthetic route largely avoids problematic impurities with chloroacetic acid, iminodiacetic acid or dihydrotriazine that occur in other routes. Is obtained analogously the physiological precursor Guanidinoacetic acid by reaction of cyanamide with glycine.

Derived compounds

• Calcium cyanamide ( fertilizer )
• Melamine
• Dicyandiamide
• Urea
• Thiourea
• Guanidines
• Carbodiimides R -N = C = N -R '
• Dicyanamin HN ( CN) 2

Safety

Cyanamid is a contact poison that can exert its effect by absorption through the skin. Absorption through the respiratory tract is unlikely due to the hygroscopic character and the low vapor pressure of the substance. The absorption through the stomach and digestive tract is rapid, but incomplete.