Beilstein J. Org. Chem. 2017, 13, 1184–1188.
thioamides [20], initial thionation of the thiocyanate function- 2-(Phenylthio)ethanethiol (8)
ality with P2S5 to give the corresponding dithiocarbamate deriv- Oil (1.51 g, 89%). IR (KBr, νmax): 3059, 2964, 2363, 1261,
ative which, in presence of residual phosphoric acid of P2S5, 1094, 1026 cm−1; 1H NMR (600 MHz, CDCl3) δ 7.30–7.28 (m,
acidic hydrolysis of S-thiocarbamates [21]. Although, we were SCH2), 1.18 (s, 1H, SH); 13C{1H} NMR (125 MHz, CDCl3) δ
not able to isolate the S,S-dithiocarbamate intermediate from the 133.97, 129.28, 128.91, 128.07, 128.03, 125.59, 36.64, 32.17;
reaction between thiocyanate and P2S5, its formation was indi- EIMS (m/z): 51 (16), 61 (23), 66 (8), 69 (12), 77 (17), 78 (8), 91
sized separately [22], with P2S5 under similar reaction condi- (ESI) m/z: [M + Na]+ calcd for C8H10S2Na, 193.0224; found,
tions to give the corresponding thiol (80%). It could be believed 193.0225.
that thionation of benzyl S-thiocarbamate led to the formation
of benzyl S,S-dithiocarbamate which underwent acidic hydroly- 3-Chlorobenzylthiol (11)
sis to give the corresponding thiol.
Oil (1.28 g, 81%). IR (KBr, νmax): 2965, 2363, 1262, 1096,
026 804 cm−1; 1H NMR (600 MHz, CDCl3) δ 7.25–7.17 (m,
2H), 7.13–7.04 (m, 3H), 3.49 (s, 2H, CH2), 1.18 (s, 1H, SH);
1
Conclusion
In summary, the method described in this paper presents an effi- 13C{1H} NMR (125 MHz, CDCl3) δ 136.26, 133.27, 128.77,
cient and direct route for the conversion of organic thio- 128.44, 126.67, 126.50, 41.60; EIMS (m/z): 63 (12), 75 (6), 89
cyanates to the corresponding thiols. It further provides an indi- (23), 99 (7), 125 (100), 127 (31), 158 (34), 160 (12); HRMS
rect route for the conversion of alkyl halides and alcohols to the (ESI) m/z: [M + Na]+ calcd for C7H7ClSNa, 180.995; found,
corresponding thiols through their thiocyanate derivatives. 180.9956.
Unlike the reported methods, the present method works under
non reductive conditions and eliminates the use of harsh and 3-Phenoxybenzylthiol (15)
expensive reducing agents, as required by the reported methods. Oil (1.68 g, 78%). IR (KBr, νmax): 3150, 2958, 2363, 1539,
In this way, this method presents an attractive method for 1249, 1032 cm−1; 1H NMR (600 MHz, CDCl3) δ 7.34–7.24 (m,
the preparation of thiols which, in addition, can be useful 3H), 7.10–6.87 (m, 6H), 3.87 (d, J = 12 Hz, 2H, CH2), 1.75 (t, J
for the generation of a thiol functional group during a total syn- = 12 Hz, 1H, SH); 13C{1H} NMR (125 MHz, CDCl3) δ 157.50,
thesis.
156.94, 143.11, 129.92, 129.76, 123.37, 122.77, 119.01, 118.34,
17.29, 28.70; EIMS (m/z): 51 (12), 77 (17), 89 (9), 91 (8), 153
(10), 168 (11), 181 (10), 183 (100), 184 (15), 216 (71), 217
1
Experimental
General experimental procedure: In a three-neck round (10); HRMS (ESI) m/z: [M + Na]+ calcd for C13H12OSNa,
bottom flask, to a solution of thiocyanate (10 mmol) in toluene 239.0609; found, 239.0611.
(
25 mL), P2S5 (2.22 g, 10 mmol) was added and the resulting
suspension was refluxed till complete consumption of the
starting material (TLC). After the reaction was complete, the
reaction mixture was quenched by careful addition of water
Supporting Information
Supporting Information File 1
(
10 mL), extracted with ethyl acetate (3 × 10 mL), the organic
Typical experimental procedure, 1H and 13C spectra of 7, 8,
phase was dried over sodium sulfate and evaporated under
reduced pressure to get the crude product which was purified by
flash chromatography (hexane–ethyl acetate) to get the pure
thiol.
3
-Phenoxypropylthiol (7)
Acknowledgements
Oil (1.43 g, 85%). IR (KBr, νmax): 3155, 3065, 2929, 2872, The authors thank Dr Lokendra Singh, Director, DRDE,
2
7
362, 1695, 1598, 1242 cm−1; 1H NMR (600 MHz, CDCl3) δ Gwalior for his support and encouragement.
.30–7.27 (m, 2H), 6.96–6.89 (m, 3H), 4.06 (t, J = 12 Hz, 2H,
OCH2), 3.42 (t, J = 12 Hz, 2H, SCH2), 2.21 (qn, J =12 Hz, 2H, References
CCH2), 1.28 (s, 1H, SH); 13C{1H} NMR (125 MHz, CDCl3) δ
58.66, 129.51, 120.91, 114.53, 65.98, 33.62, 28.77; EIMS
m/z): 51 (7), 65 (12), 66 (8), 74 (10), 75 (7), 77 (16), 94 (100),
5 (8), 168 (20); HRMS (ESI) m/z: [M + Na]+ calcd for
C9H12OSNa, 191.0609; found, 191.0610.
1. Roberts, J. S. Kirk-Othmer Encyclopedia of Chemical Technology;
Wiley-VCH: Weinheim, 1997.
1
2.
Roy, K.-M. Thiols and Organic Sulfides. Ullmann's Encyclopedia of
(
9
1187