Phosphorus hydrogen iodide

Hydrogen iodide is prepared in a similar way to hydrogen bromide, by the action of water on a mixture of iodine and violet phosphorus. TTie hydrogen iodide evolved may be collected by downward delivery or may be condensed (b.p. 238 K) it reacts with mercury and so cannot be collected over the latter. 

The hydrolysis of phosphorus tribromide or triiodide is used in the preparation of hydrogen bromide and hydrogen iodide respectively ... 

Hydrogen iodide. This gas may be conveniently prepared by allowing a solution of two parts of iodine in one part of hydriodic acid, sp. gr. 1 7 (for preparation, see Section 11,49,2), to drop on to excess of red phosphorus. The evolution of hydrogen iodide takes place in the cold when the evolution of gas slackens considerably, the mixture should be gently warmed. 

There have been several accidents with metalloids detonation with fluorine very violent reaction with boron at 700°C, and ignition with white phosphorus. In the last case, the dangerous character of the reaction of the preparation of hydrogen iodide by distillation of the phosphorus/moist iodide mixture was also mentioned. The formation of phosphonium iodide often causes the conduits of the apparatus to block, which causes the apparatus to detonate due to overpressure. Several accidents involve this factor, which is not due to a reaction that is intrinsically dangerous. 

With phosphorus, there is conversion into phosphine under the effect of hydrogen iodide. Phosphine combusts spontaneously when oxygen is present. 

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... 

Reduction of carbonyl to methylene in aromatic ketones was also achieved by (dane prepared from lithium aluminum hydride and aluminum chloride [770], by soditim borohydride in triiluoroacetic acid [841 with triethylsilane in trifluoroacetic acid [555, 777], with sodium in refluxing ethanol [842], with zinc in hydrochloric acid [843] and with hydrogen iodide and phosphorus [227], geiibrally in good to high yields. 

Thermopsamine was isolated from Thermopsis lanceolata R. Br. (137). There are two absorption bands of an axial hydroxyl group at 3370 and 1023 cm and bands representative of rrans-quinolizidine at 2680-2800 cm Mn the IR spectrum. Heating of thermopsamine with hydrogen iodide over red phosphorus... 

The reaction between dry phosphine and hydrogen iodide, first described in 1817 by J. J.Houtonde la Billardiere produces phosphonium iodide. The simplest laboratory preparation of this compound is by the hydrolysis of an intimate mixture of diphosphorus tetraiodide and white phosphorus According to X-ray diffraction investigations, phosphonium iodide crystallises in a caesium chloride type lattice 3m,32s). 326) hydrogen atoms... 

Phenylethyl Iodide. Use 146 g. (142 ml.) of (J-phenylethyl alcohol (b.p. 216 5-217°), 16 54 g. of purified red phosphorus and 154 g. of iodine. Lag the arm C (Fig.///, 40, 1) with asbestos cloth. Heat the alcohol - phosphorus mixture to boiling until sufficient alcohol (usually one-third to one-half of the total volume) passes into the reservoir B to dissolve all the iodine. Remove the flame and add the iodine solution at such a rate that the mixture boils gently. A little hydrogen iodide is evolved towards the end of the reaction. Allow the mixture to cool, add water and filter off the excess of phosphorus. Decolourise the filtrate with a little sodium bisulphite and add ether to assist in the separation of the water layer. Wash the ethereal solution with water, dry with anhydrous potassium carbonate, and distil under diminished pressure. B.p. 114 116°/12 mm. Yield 215 g. 

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