Tellurium tetrachloride: an improved method of preparation

Article abstract of DOI:10.1016/j.tetlet.2008.02.085

An efficient and practical synthesis of tellurium tetrachloride from elemental tellurium and sulfuryl chloride is described.

Full text of DOI:10.1016/j.tetlet.2008.02.085

Available online at www.sciencedirect.com
Tetrahedron Letters 49 (2008) 2371–2372
Tellurium tetrachloride: an improved method of preparation
a,
b
b,
*
*
Nicola Petragnani , Samuel R. Mendes , Claudio C. Silveira
a Instituto de Quı´mica, Universidade de Sa˜o Paulo, Caixa Postal 26077, 05599-970 Sa˜o Paulo, SP, Brazil
b Departamento de Quı´mica, Universidade Federal de Santa Maria, Caixa Postal 5001, 97105-970 Santa Maria, RS, Brazil
Received 13 December 2007; revised 28 January 2008; accepted 14 February 2008
Available online 19 February 2008
Abstract
An efficient and practical synthesis of tellurium tetrachloride from elemental tellurium and sulfuryl chloride is described.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Tellurium tetrachloride; Sulfuryl chloride; Tellurium
Tellurium, once regarded as an exotic chemical element,
became the key component of a variety of versatile and
useful reagents for organic synthesis. The multiple applica-
tions of organotellurium chemistry have been well
described in a number of review articles and books.1–8
Of the many inorganic tellurium reagents employed to
introduce tellurium in organic substrates, such as elemental
tellurium, alkali tellurides and ditellurides, hydrogen tellu-
ride and tellurium dioxide, tellurium tetrachloride deserves
a special role. TeCl4 reacts with activated aromatic com-
pounds, with organo-chloromercury compounds, with aro-
matic Grignard reagents and with several active methylene
groups; adds to double and triple C–C bond; and partici-
pates in the synthesis of tellurium heterocycles.8
We describe here a very simple and straightforword pro-
cedure for the preparation of tellurium tetrachloride, which
employs sulfuryl chloride (SO2Cl2) as chlorine source
(Scheme 1).
By heating at reflux a suspension of elemental tellurium
in excess of sulfuryl chloride, a white to light-gray solid of
the tellurium tetrachloride is formed gradually.10 The yield
is almost quantitative. The excess of sulfuryl chloride can
be recovered and reused. For most purposes, after the
removal of the excess of sulfuryl chloride the reagent is
ready to be used in situ. With the aim of proving the merit
of this new method, some previously described reactions
were performed, attaining good, compatible results:
Tellurium tetrachloride has been usually prepared by the
reaction of elemental tellurium with chlorine gas. In spite
of the high yields attained, the procedure is rather tedious
and laborious, certainly in agreement with the opinion of
previous researchers, since a particular glass apparatus8,9
is used, in which the tellurium tetrachloride produced is
distilled under a continuous chlorine stream into connected
tubes. After solidification of the product, the tubes are
detached from the apparatus. By this procedure, tellurium
tetrachloride is a pale yellow crystalline solid (mp 225 °C).
– Reaction of TeCl4 with activated aromatic compounds
giving aryl tellurium trichlorides 2a–b and ditellurides
3a–b by NaBH4 reduction in situ (Scheme 2).11–13
– Addition of TeCl4 to phenyl acetylene giving 2-chloro-2-
phenylvinyltellurium trichloride 5, and by the use of
phenyl acetylene in excess the corresponding bis-vinylic
telluride 6 is formed (Scheme 3).14,15
– Reaction of TeCl4 with 4 equiv of aryl magnesium
bromides, giving symmetrical diaryl tellurides (Scheme
4).16,17
Teo
Scheme 1.
TeCl4
SO2Cl2
reflux, 12 h
*
Corresponding authors. Tel./fax: +55 55 32208754 (C.C.S.).
E-mail address: silveira@quimica.ufsm.br (C. C. Silveira).
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.02.085

2372
N. Petragnani et al. / Tetrahedron Letters 49 (2008) 2371–2372
TeCl4
Acknowledgement
NaBH4 / H2O
THF, 0 C, air
ArTeCl3
Ar-H
ArTeTeAr
no solvent
120 ºC
º
1a-b
2 a-b
The authors thank FAPERGS, MCT/CNPq, and
CAPES for financial support.
Ar = p
-CH3OC6H4 3a 94% (Lit.12 95%)
p-CH3C6H4
3b 83% (Lit.19 49%)
Scheme 2.
References and notes
1. Tellurium; Cooper, W. C., Ed.; Van Nostrand Rheinhold: New York,
1971.
2. Engman, L. Acc. Chem. Res. 1985, 18, 274.
3. Petragnani, N.; Comasseto, J. V. Synthesis 1986, 1.
4. Irgolic, K. Y. In Houben-Weyl Methods of Organic Chemistry, 4th ed.;
Klamann, D., Ed.; Georg Thieme: Stuttgart, 1990; Vol. E12b.
5. Petragnani, N.; Comasseto, J. V. Synthesis 1991, 793. 897.
6. Petragnani, N. In Tellurium in Comprehensive Organometallic Chem-
istry II; McKillop, A., Ed.; Pergamon Elsevier, 1995; Vol. 11, Chapter
14.
Cl
Ph
Cl
Ph
Ph
TeCl4
4
Te
Ph
benzene, r.t.
4
TeCl3
Cl
Cl
Cl
6
5
mp 205 - 210 ºC; 84% (Lit.14 205 - 215 ºC; 83%)
Scheme 3.
7. Petragnani, N.; Stefani, H. A. Tetrahedron 2005, 61, 1613.
8. Petragnani, N.; Stefani, H. A. Tellurium in Organic Synthesis—Best
Synthetic Methods, 2nd ed.; Academic Press: London, 2007.
9. Suttle, Y. F.; Smith, C. R. F. Inorg. Synth. 1956, III, 140.
10. Preparation of TeCl4: In a two neck flask, equipped with a reflux
condenser and a drying tube, tellurium (10.16 g, 80 mmol) was treated
with sulfuryl chloride (50 mL; excess) added dropwise. The suspen-
sion was refluxed for 12 h, cooled to room temperature and the excess
of sulfuryl chloride distilled to dryness, leaving a white to light-gray
solid in the flask. Argon atmosphere was then introduced. The solid
was washed with dry hexanes (2 Â 50 mL), the solvent removed with a
syringe and TeCl4 is ready to use for most purposes. It can be further
dried under vacuo and transferred to a glass bottle. Isolated yield:
19.71 g (91.6%); mp 215 °C (lit.9 225 °C).
1. ether/benzene
0 ºC to reflux
Ar2TeBr2
TeCl4
4 ArMgBr
2. Br2, CCl4
7
8
Ar = Ph 89%(Lit.17 91%)
Scheme 4.
TeCl3
EtOH
TeCl4
CCl4
11. Petragnani, N. Tetrahedron 1960, 11, 15 and references cited therein.
12. Chieffi, A.; Menezes, P. H.; Comasseto, J. V. Organometallics 1997,
16, 809.
reflux, 2 h
OEt
9
13. Preparation of aryltellurium trichlorides and diaryl ditellurides: A one-
necked round-bottomed flask containing tellurium tetrachloride
(1.35 g, 5 mmol; prepared as above from 5 mmol of Te) was heated
to 120 °C and the corresponding aromatic compound (5 mmol) was
added at once, dissolving TeCl4 promptly. An evolution of HCl was
observed and a yellow solid was formed. The system was cooled to
room temperature and the trichloride was used crude in the reduction
procedure with NaBH4, according to a procedure described by
Comasseto.16 Bis(4-methoxyphenyl)ditelluride (3a): Yield 1.10 g
(94%); mp 57.6–59.0 °C (lit.20 mp 58–59 °C) Bis(4-methylphenyl)ditel-
luride (3b): Yield 0.89 g (83%); mp 50.1–51.2 °C (lit.19 mp 51 °C).
14. Moura Campos, M.; Petragnani, N. Tetrahedron 1962, 18, 527.
15. Cunha, R. L. O. R.; Zuckerman-Schpector, J.; Caracelli, I.; Comas-
seto, J. V. J. Organomet. Chem. 2006, 691, 4807; Uemura, S.; Miyoshi,
H.; Okano, M. Chem. Lett. 1979, 1357.
mp 98 - 100 ºC; 66% (Lit.18 97 -98 ºC; 63%)
Scheme 5.
– Reaction of TeCl4 with alkenes, such as cyclohexene, in
ethanol giving 2-ethoxy cyclohexyltellurium trichloride
(9) (Scheme 5).18
By our method, the preparation of TeCl4 can be per-
formed both in small amounts (1–2 mmol) and in large
amounts, such as starting with 10 g of tellurium, with com-
parable high yields.
16. Rheinboldt, H.; Petragnani, N. Chem. Ber. 1956, 89, 1270.
17. McWhinnie, W. R.; Patel, M. G. J. Chem. Soc., Dalton Trans. 1972,
199.
18. Sabir Ali, M. E.; Azad Malik, M.; Smith, B. C. C. Inorg. Chim. Acta
1989, 162, 157.
In conclusion, we described here a very easy and conve-
nient method for the preparation of TeCl4 that can be used
in situ for further transformations or isolated and stored.
The procedure is quite simple, for example, allowing the
one-pot preparation of diaryl ditellurides from elemental
tellurium in very high yields.
19. Haller, W. S.; Irgolic, K. J. J. Organomet. Chem. 1972, 38, 97.
20. Bergman, J. Tetrahedron 1972, 28, 3323.