Thiourea


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thiourea

[¦thī·ō·yu̇′rē·ə]
(organic chemistry)
(NH2)2CS Bitter-tasting, white crystals with a melting point of 180-182°C; soluble in cold water and alcohol; used in photography and photocopying, as a rubber accelerator, and as an antithyroid drug in treating hyperthyroidism. Also known as thiocarbamide.

Thiourea

 

(or thiocarbamide), H2NC(S)NH2, a white crystalline substance with a bitter taste. Melting point, 180°–182°C upon rapid heating (decomposes upon slow heating). Moderately soluble in water, methanol, and pyridine, and freely soluble in 50 percent aqueous pyridine.

Thiourea is obtained by isomerization of ammonium thiocyanate (a) and by the addition of hydrogen sulfide to cyanamide (b):

Hydrolysis of thiourea yields ammonia, hydrogen sulfide, and carbon dioxide. Alkylation of thiourea produces the S-alkyl derivatives of isothiourea, S-alkylisothiouric salts (I), which decompose under the action of alkalies to form mercaptans (II):

where X is a halogen and R is an alkyl.

Thiourea is used in the synthesis of various organic compounds, including pharmaceuticals, and as a growth substance. Thiourea yields inclusion compounds with branched and cyclic alkanes, but not with hydrocarbons of normal structure. This property is used for the separation of these two groups of compounds.

B. L. DIATKIN

References in periodicals archive ?
IRIS Integrated Risk Information System: Ethylene Thiourea (ETU) (CASRN 96-45-7) [website].
It is considered an effective lixiviant for gold with comparable dissolution rates to those of thiourea with much greater stability against oxidative decomposition.
The same procedure was repeated for the dyed textile material treated with thiourea.
Potential CEC values of the original biochars (untreated and unwashed) and acid-treated and -washed biochars, as determined using the silver thiourea method, are presented in Table 4.
Platers do not like to do large volumes of immersion tin because of the difficulties in disposing of the wastes, principally thiourea or other nasty chemicals required to get the tin to bond to copper.
Serum samples were diluted in 5 mol/L urea, 2 mol/L thiourea, 4% (wt/vol) CHAPS, 65 mmol/L dithiothreitol, 2 mmol/L tributylphosphine, 150 mmol/L nondetergent sulfobetaine-256 (NDSB-256), and 0.
The list runs from aboideau to zoonomia, and includes terms such as azotemia, banlieue, etouffee, ibogaine, mazaedia, oceanaut, pahoehoe, retiarii, thiourea and uxorious.
This complex with deprotonated thiourea is believed to have dimerized with the massive loss of 6 molecules of ammonia and the molecule of water, which was not part of the inner complex.
Their main weaknesses are their use of the carcinogenic ingredient thiourea, and the evidence of occasional whiskering as well as intermetallic formation.
One of the greatest exponents of this in the 1920s and '30s was the Birmingham firm of Brookes and Adams who purchased thiourea urea moulding powder from their neighbours at British Cyanides in the West Midlands,' writes Mr Glover.
Guanidine, urea, or thiourea substituted carboxylic acids or their salts as deposit control agents also reduce wear [29].
As well as this it is advisable to avoid foods containing thiourea, a protein which prevents the absorption of iodine.