Catechylphosphorus Trichloride1


[2007-97-8]  · C6H4Cl3O2P  · Catechylphosphorus Trichloride  · (MW 245.43) (tribromide)

[3712-44-5]  · C6H4Br3O2P  · Catechylphosphorus Tribromide  · (MW 378.81)

(chlorinating reagent; exchange of oxygen and sulfur to chlorine)

Alternate Names: CPT; 2,2,2-trichloro-2,2-dihydro-1,3,2-benzodioxaphosphole.

Physical Data: mp 61-62 °C; bp 132-135 °C/12 mmHg; 31P NMR: d -26 ppm.

Solubility: sol CH2Cl2, CHCl3, CCl4, Et2O, benzene, hexane; reacts violently with H2O and other protonic solvents, also with alcohols, acetone, DMF, THF.

Form Supplied in: pale yellow solid; commercially available.

Handling, Storage, and Precautions: the solid must be stored in absence of moisture; the dissolved solid is easy to handle; the substance is corrosive and toxic on contact. This reagent should be handled in a fume hood.

Reactions with catechylphosphorus trichloride (CPT) are normally carried out by heating (30 min, water bath) without solvents (other conditions are described, see equations). The products must be separated by distillation from the catechylphosphoryl (bp 120-122 °C/13 mmHg) or thiophosphoryl chloride (bp 114 °C/13 mmHg) also formed. Normally the boiling points of the products are lower than those of the byproducts.

Displacement of Double-Bonded Oxygen or Sulfur by Chlorine.

CPT converts carboxylic acids and dithiocarboxylic acids to acid chlorides (eqs 1 and 2).1-3 Also sulfonic, phosphinic, and phosphonic acids react in the same way to give the corresponding acid chlorides (eqs 3-5; RŽ = H).1,4,5

Esters of phosphinic, phosphonic, and carboxylic acids were cleaved by CPT to alkyl chlorides and acid monochlorides or dichlorides (eqs 4-6; RŽ = Alk).1,5 Anhydrides of carboxylic acids also react with CPT to give acid chlorides (eq 7).1,2

In all cases the yield of acid chlorides is higher than the yield of the reactions with PCl5.

CPT converts alkyl formates to a,a-dichloromethyl alkyl ethers1,2,6 and N,N-disubstituted formamides to the corresponding amide dichlorides (eqs 8 and 9);1 in particular, dimethylformamide dichloride (Vilsmeier reagent) was obtained in high yield and very good purity.

Both types of dichlorides are good chlorinating reagents. The reactions of unsubstituted amides, urethanes, and dithiocarbamides with CPT give nitriles,1,2 isocyanates,1,2,7 and isothiocyanates,8 respectively, in good yields (eqs 10-12).

Displacement of Single-Bonded Oxygen or Sulfur by Chlorine.

CPT converts alcohols to alkyl chlorides1,9 and cyclic ethers (e.g. THF or ethylene oxide) to a,o-dichloroalkanes (eqs 13 and 14).1,2 Acetals and hemiacetals were cleaved by CPT to a-chloro ethers and alkyl chlorides and HCl, respectively (eq 15).1,10 Trialkyl trithioorthoformate reacts with CPT to give the stable dialkyl chlorodithioorthoformate (eq 16).11

CPT converts phosphites to chlorophosphites (eq 17);1,12 it is the best method for the synthesis of pure diethyl chlorophosphite.12 Silyl ethers or disiloxanes react with CPT to give silyl chlorides (eq 18).1

Catechylphosphorus Tribromide.

This reagent reacts in the same way. It is particularly suitable for the synthesis of acid bromides from acids,13 a,a-dibromomethyl alkyl ethers from alkyl formates,14 and trimethylsilyl bromide from hexamethyldisiloxane.15

Related Reagents.

2-Chloroethyl Dichloromethyl Ether; Dichloromethyl Methyl Ether; Dimethylchloromethyleneammonium Chloride; Oxalyl Chloride; Phosphorus(III) Chloride; Phosphorus(V) Chloride; Phosphorus Oxychloride; Thionyl Chloride.

1. (a) Gloede, J. ZC 1982, 22, 126 (CA 1982, 97, 5406z). (b) FF 1967, 1, 120.
2. Gross H.; Gloede, J. CB 1963, 96, 1387 (CA 1963, 59, 2734h).
3. Barnikow, G.; Gabrio, T. ZC 1968, 8, 142 (CA 1968, 68, 114 227p).
4. Siegemund, G.; Schwertfeger, W. CA 1982, 97, 5801z.
5. (a) Henning, H.-G. ZC 1965, 5, 103 (CA 1965, 63, 1812c). (b) Kovaleva, T. V.; Martynyuk, E. G.; Semenii, V. Ya. ZOB 1989, 59, 2512 (CA 1990, 112, 235 432n).
6. Bou, A.; Pericas, M. A.; Serratosa, F. CA 1978, 89, 129 692u.
7. Drach, B. S.; Kovalev, V. A.; Popovich, T. P. ZOR 1978, 14, 880 (CA 1978, 89, 42 313x).
8. Martin, D.; Beyer, E.; Gross H. CB 1965, 98, 2425 (CA 1965, 63, 6893g).
9. Fessner, W.-D.; Murty, B. A. R. C.; Spurr, P. R.; Pinkos, R.; Melder, J.-P.; Fritz, H.; Prinzbach, H. CB 1992, 125, 1697 (CA 1992, 117, 89 868u).
10. Siegemund, G. CB 1973, 106, 2960 (CA 1974, 80, 3031y).
11. Gross, H.; Keitel, I.; Costisella B.; Mikolajczyk, M.; Midura, W. PS 1983, 16, 257 (CA 1983, 100, 34 611y).
12. Gloede, J.; Mikolajczyk, M.; Lopusinski, A.; Omelanczuk, J. JPR 1974, 316, 703 (CA 1974, 81, 169 038b).
13. Gloede, J.; Gross H. CB 1967, 100, 1770 (CA 1967, 67, 21 546f).
14. Gross, H.; Karsch, U. JPR 1965, 29, 315 (CA 1965, 63, 11 338f).
15. Gross H.; Böck, Ch.; Costisella, B.; Gloede, J. JPR 1978, 320, 344 (CA 1978, 89, 109 767u).

Jörg Gloede

Institut für Angewandte Chemie, Berlin-Adlershof, Germany

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