Dimethylamino difluorophosphine

The apparatus consists of a 2-1., three-necked, round-bottomed flask equipped with a mechanical stirrer, a pressure-equalized dropping funnel through which dry nitrogen can be added, and a reflux condenser, and is to be maintained at 0°. The outlet tube on the reflux condenser leads to a large U-tube trap, fitted with stopcocks on both sides, and immersed in a Dry Ice-isopropyl alcohol bath. The U-trap vents to a mineral oil bubbler. (See Fig. 17.) Sodium fluoride, 454 g. (10.8 mols) is added to the flask followed by approximately 1200 ml. of tetramethylene sulfone. The system is then flushed thor- 

This preparation was checked on a one-tenth scale and the observed yield was 53%. 

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Dimethylamino)difluorophosphine has been prepared directly from phosphorus trifluoride and dimethylamine5,6 and also by the action of dimethylamine on (triehloromethyl)difluorophos-phine.13 The most convenient procedure yet reported4 appears to be the fluorination of C12PN(CH3)2 using ant mony trifluoride or sodium fluoride as a fluorinating agent. 

After the addition of C12PN(CH3)2 is complete, the reaction mixture is heated to 50 to 60° for one hour. The water is then drained from the reflux condenser, and the dropping funnel is replaced with a tube by means of which dry nitrogen can be bubbled through the mixture. With the mixture maintained at 50 to 60°, the (dimethylamino)difluorophosphine is carried into the U-tube trap by the nitrogen stream. This should be continued for a period of several hours to ensure a good yield. The U-tube trap is then attached to a vacuum system, and the contents are distilled through U-traps held at... 

Dimethylamino)difluorophosphine is a water-white liquid with the following physical constants melting point, —86° ... 

In a typical experiment, a 12.18-mmol sample of hydrogen chloride is frozen into a 500-ml. reaction bulb on the vacuum system. (Liquid nitrogen is the refrigerant.) An 8.22-mmol sample of (dimethylamino)difluorophosphine is then frozen into the bulb, the stopcock to the bulb is closed, and the system is allowed to warm slowly to 25°. Reaction is indi-... 

This procedure differs from those outlined for the bromo and chloro derivatives in that an appreciable excess of (dimethyl-amino) diflu orophosphine cannot be used because it is difficult to separate from iododifluorophosphine by fractional condensation. Typically, (dimethylamino)difluorophosphine (6.38 mmol) and hydrogen iodide (12.76 mmol) are condensed into a 500-ml. reaction bulb and allowed to warm slowly to 25°. As reaction ensues, f the white solids are discolored by formation of red phosphorus triiodide which probably results from a disproportionation 3PF2I —> 2PF3 + PI3. Thus, when the products are separated by fractional condensation through —126° (methylcyclohexane slush) to —196°, an appreciable amount of... 

On heating with PCI3, the fluorine is replaced by chlorine and a mixed trihalide is produced. A mixed trihalide also results when a hydrogen halide is used. If dimethylamino difluorophosphine is treated with chlorine or bromine at low temperatures, a pentaphosphorane is produced, which will in turn react with sulphur dioxide to give dimethylamino fluorophosphine oxide. A 6-coordinated phosphoride anion is obtained in a reaction with KHF2 (7.107). 

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