Thiobenzophenone

Thiobenzophenone
Names
	Preferred IUPAC name Diphenylmethanethione
Identifiers
CAS Number	1450-31-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	502886 ;
PubChem CID	578536;
UNII	JYQ6P4G3UJ ;
CompTox Dashboard (EPA)	DTXSID50342088 ;
	InChI InChI=1S/C13H10S/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: XDDVRYDDMGRFAZ-UHFFFAOYSA-N ; InChI=1/C13H10S/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: XDDVRYDDMGRFAZ-UHFFFAOYAD;
	SMILES S=C(C1=CC=CC=C1)C2=CC=CC=C2;
Properties
Chemical formula	C13H10S
Molar mass	198.28 g·mol−1
Appearance	Deep blue solid
Melting point	53 to 54 °C (127 to 129 °F; 326 to 327 K)
Boiling point	174 °C (345 °F; 447 K)
Hazards
Flash point	no
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Thiobenzophenone is an organosulfur compound with the formula (C₆H₅)₂CS. It is the prototypical thioketone. Unlike other thioketones that tend to dimerize to form rings and polymers, thiobenzophenone is quite stable, although it photoxidizes in air back to benzophenone and sulfur.^[1] Thiobenzophenone is deep blue and dissolves readily in many organic solvents.

Structure

The C=S bond length of thiobenzophenone is 1.63 Å, which is comparable to 1.64 Å, the C=S bond length of thioformaldehyde, measured in the gas phase. Due to steric interactions, the phenyl groups are not coplanar and the dihedral angle SC-CC is 36°.^[2] A variety of thiones with structures and stability related to thiobenzophenone have also been prepared.^[1]

Synthesis

One of the first reported syntheses of thiobenzophenone involves the reaction of sodium hydrosulfide and diphenyldichloromethane:^[3]

Ph₂CCl₂ + 2 NaSH → Ph₂C=S + 2 NaCl + H₂S

An updated method involves sulfiding of benzophenone:^[4]

Ph₂C=O + H₂S → Ph₂C=S + H₂O

In the above reaction scheme, a mixture of gaseous hydrogen chloride and hydrogen sulfide are passed into a cooled solution of benzophenone in ethanol. Thiobenzophenone can also be produced by a Friedel-Crafts reaction of thiobenzoyl chloride and benzene.^[5]

Reactivity

Due to the relative weakness of the C=S bond, thiobenzophenone is more reactive than benzophenone. Thiobenzophenone (as well as other thioketones) is a dipolarophiles and dienophiles. For example, it combines with 1,3-dienes in Diels-Alder cycloadditions.^[6] The rate of thioketones in cycloadditions is related but not limited to the size of the small HOMO/LUMO energy gap of the π-MOs of the C=S double bond.^[2] Reactions between thiobenzophenone and most dienes yield Diels-Alder adducts whereas reactions with monoolefins yield bicyclic compounds.^[7]

References

^ ^a ^b Metzner, Patrick (1999). "Thiocarbonyl Compounds as Specific Tools for Organic Synthesis". Organosulfur Chemistry I. Topics in Current Chemistry. Vol. 204. pp. 127–181. doi:10.1007/3-540-48956-8_2. ISBN 978-3-540-65787-3.
^ ^a ^b Sustmann, R.; Sicking, W.; Huisgen, R. "A Computational Study of the Cycloaddition of Thiobenzophenone S-Methylide to Thiobenzophenone". J. Am. Chem. Soc. 2003, 125, 14425-14434. doi:10.1021/ja0377551
^ H. Staudinger, H. Freudenberger "Thiobenzophenone" Organic Syntheses, 1931, Vol. 11, p.94. doi:10.15227/orgsyn.011.0094
^ B. F. Gofton and E. A. Braude "Thiobenzophenone" Org. Synth. 1955, vol. 35, 97. doi:10.15227/orgsyn.035.0097
^ Horst Viola, Steffen Scheithauer and Roland Mayer "Organische Schwefelverbindungen,97. Friedel-Crafts-Reaktionen mit Thiosäurechloriden" Chem. Ber. 1968, volume 101, pages 3517–3529. doi:10.1002/cber.19681011024
^ Fisera, Lubor; Huisgen, R.; Kalwinsch, Ivars; Langhals, Elke; Li, X.; Mloston, G.; Polborn, K.; Rapp, J.; Sicking, W.; Sustmann, R. (1996). "New Thione Chemistry". Pure and Applied Chemistry. 68 (4): 789–798. doi:10.1351/pac199668040789. S2CID 97484311.
^ Okuma, Kentaro; Yamamoto, Toshiro; Shirokawa, Takafumi; Kitamura, Tsugio; Fujiwara, Yuzo (1996). "The First Isolation of Benzyne-Thiobenzophenone Adducts". Tetrahedron Letters. 37 (49): 8883–8886. doi:10.1016/S0040-4039(96)02074-6.

[Organosulfur-1] Metzner, Patrick (1999). "Thiocarbonyl Compounds as Specific Tools for Organic Synthesis". Organosulfur Chemistry I. Topics in Current Chemistry. Vol. 204. pp. 127–181. doi:10.1007/3-540-48956-8_2. ISBN 978-3-540-65787-3.

[Sustmann-2] Sustmann, R.; Sicking, W.; Huisgen, R. "A Computational Study of the Cycloaddition of Thiobenzophenone S-Methylide to Thiobenzophenone". J. Am. Chem. Soc. 2003, 125, 14425-14434. doi:10.1021/ja0377551

[3] H. Staudinger, H. Freudenberger "Thiobenzophenone" Organic Syntheses, 1931, Vol. 11, p.94. doi:10.15227/orgsyn.011.0094

[4] B. F. Gofton and E. A. Braude "Thiobenzophenone" Org. Synth. 1955, vol. 35, 97. doi:10.15227/orgsyn.035.0097

[5] Horst Viola, Steffen Scheithauer and Roland Mayer "Organische Schwefelverbindungen,97. Friedel-Crafts-Reaktionen mit Thiosäurechloriden" Chem. Ber. 1968, volume 101, pages 3517–3529. doi:10.1002/cber.19681011024

[Fisera-6] Fisera, Lubor; Huisgen, R.; Kalwinsch, Ivars; Langhals, Elke; Li, X.; Mloston, G.; Polborn, K.; Rapp, J.; Sicking, W.; Sustmann, R. (1996). "New Thione Chemistry". Pure and Applied Chemistry. 68 (4): 789–798. doi:10.1351/pac199668040789. S2CID 97484311.

[7] Okuma, Kentaro; Yamamoto, Toshiro; Shirokawa, Takafumi; Kitamura, Tsugio; Fujiwara, Yuzo (1996). "The First Isolation of Benzyne-Thiobenzophenone Adducts". Tetrahedron Letters. 37 (49): 8883–8886. doi:10.1016/S0040-4039(96)02074-6.

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