tert-Butylthiol

tert-Butylthiol
IUPAC name

2-Methylpropane-2-thiol
Other names

t-BuSH, 2-methylpropane-2-thiol, 2-methyl-2-propanethiol, tert-butyl mercaptan, TBM
Identifiers
CAS number 75-66-1 Y
PubChem 6387
ChemSpider 6147 Y
Jmol-3D images Image 1
Properties
Molecular formula C4H10S
Molar mass 90.19 g mol−1
Appearance Colorless, clear liquid
Density 0.8 g/mL (25 °C)
Melting point

-0.50 °C, 273 K, 31 °F
Boiling point

62-65 °C, 335-338 K, 144-149 °F
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

tert-Butylthiol, also known as 2-methylpropane-2-thiol, 2-methyl-2-propanethiol, tert-butyl mercaptan (TBM), and t-BuSH, is an organosulfur compound with the formula (CH3)3CSH. This thiol is used as a flavoring agent and used in a wide range of organic reactions.

Contents

Preparation

tert-Butylthiol does not occur naturally. The compound was first prepared in 1932 by the reaction of the Grignard reagent, t-BuMgCl, with sulfur to give the corresponding thiolate, followed by hydrolysis.[1] This preparation is shown below:

t-BuMgCl + S → t-BuSMgCl
t-BuSMgCl + H2O → t-BuSH + Mg(OH)Cl

Reactions

tert-Butylthiol can react with metal alkoxides and acyl chlorides to form thiol esters, as shown in the equation:[2]

In the reaction above, thallium(I) ethoxide converts to thallium(I) t-butylthiolate. In the presence of diethyl ether, thallium(I) t-butylthiolate reacts with acyl chlorides to give the corresponding tert-butyl thioesters.[3] Like other thioesters, it reverts back to tert-butylthiol by hydrolysis.[4]

Lithium 2-methylpropane-2-thiolate can be prepared by treatment of tert-butylthiol with lithium hydride in an aprotic solvent such as hexamethylphosphorous triamide (HMPT). The resulting thiolate salt is a useful demethylating reagent. For example, treatment with 7-methylguanosine gives guanosine. Other N-methylated nucleosides in tRNA are not demethylated by this reagent.[5]

Metal Complexes

The anion derived from tert-butylthiol forms complexes with various metals. One example is tetrakis(tert-butylthiolato)molybdenum(IV), Mo(t-BuS)4. This complex was prepared by treating MoCl4 with t-BuSLi:[6]

MoCl4 + 4t-BuSLi → Mo(t-BuS)4 + 4LiCl

Mo(t-BuS)4 is a dark red diamagnetic complex that is sensitive to air and moisture.6 The molybdenum center has a distorted tetrahedral coordination to four sulfur atoms, with overall D2 symmetry.[7]

See also

References

  1. ^ Rheinboldt, Heinrich; Mott, Friedrich; Motzkus, Erwin; A. D. McMaster; B. M. Mattson; S. T. Michel (1932). "Tertiäres Butylmercaptan". Journal fuer Praktische Chemie (Leipzig) 134: 257–281. doi:10.1002/prac.19321340901. 
  2. ^ Spessard, Gary O.; Chan, Wan Kit; Masamune, S. (1990). "Preparation of thiol esters: s-tert-butyl cyclohexanecarbothioate and s-tert-butyl 3α,7α,12α-trihydroxy-5β-cholane-24-thioate". Organic Syntheses 7: 87. 
  3. ^ Spessard, Gary O.; Chan, Wan Kit; Masamune, S. (1990). "Preparation of thiol esters: s-tert-butyl cyclohexanecarbothioate and s-tert-butyl 3α,7α,12α-trihydroxy-5β-cholane-24-thioate". Organic Syntheses 7: 87. 
  4. ^ "2-propanethiol, 2-methyl-". National Institute of Standards and Technology. http://webbook.nist.gov/cgi/cbook.cgi?ID=C75661&Mask=8. 
  5. ^ Ho, Tse-Lok; Fieser, Mary; Fieser, Louis (2006). "Lithium 2-methylpropane-2-thiolate". Fieser and Fieser's Reagents for Organic Synthesis. doi:10.1002/9780471264194.fos06530. 
  6. ^ Otsuka, Sei; Kamata, Masato; Hirotsu, Ken; Higuchi, Taiichi (1981). "A Novel Molybdenum Thiolato Compound, Tetrakis(tert-butylthiolato)molybdenum( IV). Preparation and Crystal and Molecular Structure". J. Am. Chem. Soc. 103: 3011–3014. doi:10.1021/ja00401a017. 
  7. ^ Otsuka, Sei; Kamata, Masato; Hirotsu, Ken; Higuchi, Taiichi (1981). "A Novel Molybdenum Thiolato Compound, Tetrakis(tert-butylthiolato)molybdenum( IV). Preparation and Crystal and Molecular Structure". J. Am. Chem. Soc. 103: 3011–3014. doi:10.1021/ja00401a017.