organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, isothiouronium is a

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

with the formula SC(NH₂)₂sup>+ (R =

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...

) and is the

acid salt An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

of isothiourea. The H centres can also be replaced by alkyl and aryl. Structurally, these cations resemble

guanidinium Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experie ...

cations. The CN₂S core is planar and the C–N bonds are short.

Synthesis

Salts comprising these cations are typically prepared by

alkylation Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting al ...

thiourea Thiourea () is an organosulfur compound with the formula and the structure . It is structurally similar to urea (), with the oxygen atom replaced by sulfur atom (as implied by the '' thio-'' prefix). The properties of urea and thiourea differ s ...

: :SC(NH₂)₂ + RX → SC(NH₂)₂sup>+X⁻

Reactions

Hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

of isothiouronium salts gives

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl grou ...

s. : SC(NH₂)₂sup>+X⁻ + NaOH → RSH + OC(NH₂)₂ + NaX Isothiouronium salts in which the sulfur has been alkylated, such as ''S''-methylisothiourea hemisulfate (CAS number: 867-44-7), will convert

amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

s into

groups. This approach is sometimes called the Rathke synthesis after

Bernhard Rathke Heinrich Bernhard Rathke (20 January 1840 in Königsberg – 14 August 1923 in Bad Reichenhall) was a German chemist. He was the son of embryologist Martin Rathke. He studied natural sciences at the University of Königsberg, and afterwards w ...

who first reported it in 1881. : RNH₂ + H₃SC(NH₂)₂sup>+X⁻ → H₃N(H)C(NH₂)₂sup>+X⁻ + CH₃SH Chelating resins with isothiouronium groups are used to recover mercury and other noble metals including platinum from solutions.{{cite web , url = http://www.purolite.com/default.aspx?RelID=606267&ProductID=19 , title = Purolite S920 Isothiouronium Chelating Resin , publisher = Purolite , access-date = 2012-09-07 , archive-date = 2016-03-04 , archive-url = https://web.archive.org/web/20160304025747/http://www.purolite.com/default.aspx?RelID=606267&ProductID=19 , url-status = dead

References

Functional groups Thioureas Cations