1-Chloro-2-phenylacetylene

(X = Cl)

[1483-82-5]  · C8H5Cl  · 1-Chloro-2-phenylacetylene  · (MW 136.57) (X = Br)

[932-87-6]  · C8H5Br  · 1-Bromo-2-phenylacetylene  · (MW 181.03) (X = I)

[932-88-7]  · C8H5I  · 1-Iodo-2-phenylacetylene  · (MW 228.03)

(reacts with tertiary enolates to form phenylethynyl adducts; starting material for the preparation of ynamines, ynehydrazines, alkynylphosphonates, and alkynyl ethers)

Alternate Name: (chloroethynyl)benzene; phenylchloroethyne.

Physical Data: X = Cl: bp 78 °C/20 mmHg;3 X = Br: bp 40-41 °C/0.1 mmHg, d 1.456 g cm-3; X = I: bp 115-117 °C/16 mmHg, d 1.75 g cm-3.

Preparative Methods: the method of choice is by reaction of phenylacetylene with sodium hypochlorite;1 it can also be prepared by reaction of sodium phenylacetylide with p-toluenesulfonyl chloride2 or lithium phenylacetylide and N-chlorosuccinimide.3

Handling, Storage, and Precautions: use in a fume hood.

Phenylethynylation.

1-Chloro-2-phenylacetylene reacts with tertiary ketone or ester enolates to give phenylethynyl adducts (1) and (2) in 70-95% yields. Hydration of the ethynyl group leads to dicarbonyl systems (3).4 Additional enolate addition/elimination reactions with chloroacetylenes to yield alkynyl derivatives (4) and (5) have been reported for dichloroacetylene (see Trichloroethylene and 1-chloro-2-phenylthioacetylene.4 This method is limited to tertiary enolates. Similar alkynylations have been reported for tertiary b-dicarbonyl enolates using alkynyl lead triacetates5 or alkynyl iodonium tetrafluoroborates.6

Preparation of Ynamines and Ynehydrazines.

1-Chloro-2-phenylacetylene reacts with lithium dimethylamide to yield the ynamine (6) in 87% yield. Ynamines can also be prepared from the reaction with tertiary amines.7,8 Similarly, the trimethyl ynehydrazine derivative (7) can be prepared from the reaction with lithium trimethylhydrazide.9

Reaction with Other Nucleophiles.

1-Chloro-2-phenylacetylene reacts with Triethyl Phosphite, undergoing an Arbuzov reaction to yield the phosphonate (8).10 Similarly, reaction with alkoxides leads to alkoxyacetylenes (9).11

Related Reagents.

Ethoxyacetylene; Phenylthioacetylene; Trichloroethylene.


1. Miller, S. I.; Ziegler, G. R.; Wieleseck, R. OSC 1973, 5, 921.
2. Pangon, G.; Phillippe, J.-L.; Cadiot, P. CR(C) 1973, 277, 879.
3. Murray, R. E. SC 1980, 10, 345.
4. (a) Kende, A. S.; Fludzinski, P. TL 1982, 23, 2373. (b) Kende, A. S.; Fludzinski, P.; Hill, J. H.; Swenson, W.; Clardy, J. JACS 1984, 106, 3551.
5. (a) Moloney, M. G.; Pinhey, J. T.; Roche, E. G. JCS(P1) 1989, 333. (b) Hashimoto, S.; Miyazaki, Y.; Shinoda, T.; Ikegami, S. CC 1990, 1100.
6. Ochiai, M.; Ito, T.; Takaoka, Y.; Masaki, Y.; Kunishima, M.; Tani, S.; Nagao, Y. CC 1990, 118.
7. Chemistry of Acetylenes; Viehe, H. G., Ed.; Dekker: New York, 1969.
8. Dickstein, J. I.; Miller, S. I. JOC 1972, 37, 2175.
9. de Croute, H.; Janousek, Z.; Pongo, L.; Merenyi, R.; Viehe, H. G. BSF 1990, 745.
10. (a) Fujii, A.; Miller, S. I. JACS 1971, 93, 3694. (b) Burt, D. W.; Simpson, P. JCS(C) 1971, 2872.
11. (a) Tanaka, R.; Miller, S. I. TL 1971, 1753. (b) Tanaka, R.; Rodgers, M.; Simonaitis, R.; Miller, S. I. T 1971, 27, 2651.

Pawel Fludzinski

Lilly Research Centre, Windlesham, UK



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