Organic Syntheses, CV 5, 218
Submitted by R. Schmutzler
1
Checked by M. D. Hurwitz and W. D. Emmons.
1. Procedure
A
500-ml. three-necked flask is provided with a
mechanical stirrer,
thermometer, and
reflux condenser equipped with a
drying tube. The flask is flushed with dry
nitrogen and charged under
nitrogen with
502 g. (3 moles) of chloromethylphosphonic dichloride (Note
1) and
160 g. (0.36 mole) of tetraphosphorus decasulfide (Note
2). The reaction mixture is heated under reflux with stirring for 6 hours, the liquid temperature being 180–190° (Note
3). The nearly black reaction mixture is then allowed to cool to room temperature and is distilled under reduced pressure. Material distilling between
70° (40 mm.) and
150° (20 mm.) is collected (Note
4). The yield is
364–396 g. (
66–72%). There is no impurity in the material thus obtained which is detectable by gas chromatography (Note
5). The product may be redistilled if desired, although in most cases this is superfluous; b.p.
64–65° (10 mm.);
n25D 1.5730–1.5741 (Note
6). The P
31 n.m.r. spectrum of the product shows a peak at −74.2 p.p.m. relative to external
phosphoric acid.
2. Notes
2.
Technical tetraphosphorus decasulfide (Stauffer Chemical Co.) is employed. The product is weighed under
nitrogen protection.
3. In order to prevent contact of the boiling reaction mixture with air,
nitrogen is passed through a T-tube on top of the drying tube on the reflux condenser.
4. Toward the end of the distillation a thick residue is formed, and this makes the distillation difficult. After the contents of the distillation flask are cooled to room temperature, this residue may be disposed of by careful continuous rinsing with water under a
well-ventilated hood.
6. Literature
3 values are: b.p.
89° (30 mm.),
n25D 1.5741,
d2525 1.5891.
3. Discussion
4. Merits of the Preparation
The reaction of
chloromethylphosphonic dichloride with
tetraphosphorus decasulfide3,4,5 or with
thiophosphoryl chloride3 are the only methods of preparation for this compound reported. The method is applicable more generally, and the syntheses of methyl-, trichloromethyl-, ethyl-, propyl-, cyclohexyl-, phenyl-, and
p-chlorophenylphosphonothioic dichloride from the corresponding phosphonic dichlorides have been reported.
4,5 Phosphinic chlorides of varying structures could also be converted to the corresponding thiono compounds by comparable procedures.
4,5 The present method is preferable to the
thiophosphoryl chloride procedure
3,5 in that does not require working under pressure.
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