Cyanamide can be regarded as a functional single carbon fragment which can react as an
electrophile or
nucleophile. The main reaction exhibited by cyanamide involves additions of compounds containing an acidic proton. Water, hydrogen sulfide, and hydrogen selenide react with cyanamide to give
urea,
thiourea, and
selenourea, respectively: :H2NCN + H2E → H2NC(E)NH2 (E = O, S, Se) In this way, cyanamide behaves as a dehydration agent and thus can induce condensation reactions. Alcohols, thiols, and amines react analogously to give alkylisoureas, isothioureas, and
guanidines. The anti-ulcer drug
cimetidine is generated using such reactivity. Related reactions exploit the bifunctionality of cyanamide to give
heterocycles, and this latter reactivity is the basis of several pharmaceutical syntheses such as the aminopyrimidine
imatinib, and agrichemicals
Amitrol and
hexazinone. The hair-loss treatment
minoxidil and the
anthelmintics
albendazole,
flubendazole, and
mebendazole feature 2-aminoimidazole substructures derived from cyanamide. Cyanamide is also used in the synthesis of other pharmaceutical drugs including
tirapazamine,
etravirine,
revaprazan, and dasantafil. The cyanamide
anion has the character of a pseudo
chalcogen, cyanamide can therefore be regarded as analogue to
water or
hydrogen sulfide. A convenient method for the preparation of secondary amines which are not contaminated with primary or tertiary amines is the reaction of cyanamide with alkyl halides to
N,N-dialkylcyanamides which can easily be hydrolyzed to dialkylamines and then decarboxylated. Cyanamide adds itself in the presence of N-bromosuccinimide to olefinic double bonds. The addition product is converted by bases to N-Cyanaziridine, cyclized in the presence of acids to imidazolines, which can be further reacted to vicinal diamines by alkaline cleavage. Cyanamide is also a versatile synthetic building block for
heterocycles: it forms 2-aminobenzimidazole with
1,2-diaminobenzene and it forms with the readily available cyclic
enamine 4-(1-cyclohexenyl)morpholine and with elemental
sulfur a 2-aminothiazole in good yields. Sodium dicyanamide is available in good yield and high purity from cyanamid and
cyanogen chloride, which is suitable as an
intermediate for the synthesis of active pharmaceutical ingredients. A guanidino group is introduced by reaction of cyanamide with
sarcosine In the industrial synthesis of
creatine:. This synthesis route mostly avoids problematic impurities like
chloroacetic acid,
iminodiacetic acid, or
dihydrotriazine that occur in other routes. The physiological precursor
guanidinoacetic is obtained analogously by reacting cyanamide with
glycine. Methods to
stabilize cyanamide make it available on an industrial scale. Due to the strong affinity towards self-condensation in alkaline media (see above) solutions of cyanamide are stabilized by the addition of 0.5 wt% of
monosodium phosphate as buffer. Solid cyanamide is produced by careful evaporation of the solvent and subsequent addition of a hydrolysis-labile
ester of
formic acid. The ester absorbs traces of moisture (suppression of urea formation), neutralizes alkalinity (ammonia) and continually releases small amounts of formic acid.
Agricultural use Cyanamide, under the trade name Dormex, is a common agricultural
rest-breaking agent applied in spring to stimulate uniform opening of
buds, early foliation and bloom. Cyanamide can effectively compensate for the moderate lack of
chilling units accumulated in the previous autumn and save the harvest that would otherwise be lost. It is particularly effective for woody plants such as blueberries, grapes, apples, peaches and kiwifruit. Most recently the product was approved for use on almonds and pistachios in the USA. Overdosage, high concentration and error in timing of application can damage the buds (especially of
peach trees). Growers may avoid damage by applying 30 days prior to bud break according to the label. A 50% aqueous solution of cyanamide is also used as a
biocide (disinfectant) particularly in
pig farming, because it effectively kills salmonella and shigella and fights
flies in all stages of development. ==Environmental aspects==