Tetraethylphosphonium chloride

The proton-decoupled spectrum (75 MHz) for tetraethylphosphonium chloride is shown in this problem. Assign each of the carbon atoms after reviewing Section 6.15. Calculate the coupling constants for the doublets at 11.7 and 6.0 ppm. Indicate the coupling constant notations (J values) for each of these patterns (H and J). 

Proton-phosphorus coupling constants vary considerably according to the hybridization of the phosphorus atom in addition to the distance between the proton and the phosphorous. For example, tetravalent phosphorus atoms, such as in tetraethylphosphonium chloride, have coupling constants that are larger than H- H coupling constants. Often, coupling constants decrease with distance, but in this case, they increase with distance. 

FIGURE 7.75 H NMR Spectrum of tetraethylphosphonium chloride (300 MHz, CDCI3). The pattern centering on 1.33 ppm is a doublet of triplets. The pattern centering on 2.55 ppm can be described as a donblet of quartets. One of the quartets is indicated with dots. The other quartet is shown with x. 

Triethylphosphine, ( 2115)3 , is prepared in a variety of ways (1) By the action of phosphorus-sodium alloy on ethyl iodide. (2) A double compound of the phosphine with zinc chloride is produced when zinc diethyl reacts with phosphorus trichloride. (3) The phosphine IS formed together with its oxide when zinc diethyl reacts with phosphorus oxychloride. (4) By heating 1 molecular equivalent of phosphonium iodide with 3 molecular equivalents of ethyl alcohol for 6 to 8 hours at 160° to 180° C., tetraethylphosphonium iodide occurring as a by-product. This process yields the hydriodide of the phosphine. (5) By decomposition wdth potassium hydroxide of the base formed when a zinc phosphide, PHZn (prepared by the action of phosphine on zinc diethyl at a temperature not exceeding —4° C.), is heated with ethyl iodide in a sealed tube for 1 hours at 150° (6) By heating... 

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