Variable temperature 'H n,m.r. spectra of pyridine solutions of tetrakis(hydroxymethyl)phosphonium chloride indicate that chemical exchange of methyl01 groups of the salt with those of the small amount of tris(hydroxymethyl)phosphine formed is the cause of their magnetic equivalence at elevated temperatures. Triethylamine transforms the salt into the phosphine and at least two other phosphorus species which may result from reaction of formaldehyde at oxygen of the phosphine.Des spectres r.m.n. 'H a differentes temperatures de solutions de chlorure de tetrakis (hydroxymethyl) phosphonium dans la pyridine indiquent que l'echange chimique des groupements methyl01 du sel avec ceux provenant d'une petite quantite de tris (hydroxymethyl) phosphine formie, est la cause de leur Cquivalence magnetique a temperature ClevCe. La triethylamine transforme le sel en phosphine et en au rnoins deux autres produits contenant du phosphore, qu'on pourrait attribuer a la reaction de la formaldehyde avec l'oxygene de la phosphine.Canadlsn Journal of Chemistry, 49, 3581 (1971) Reaction of aqueous or alcoholic alkali hydroxide (1) or anhydrous triethylamine (2) with tetrakis(hydroxymethy1)phosphonium chloride (1) yields tris(nydroxymethyl)phosphine (3) as the isolable product. In a recent report (3) employing 'H and 31P n.m.r. in a study of the reaction of 1 with sodium hydroxide, it was concluded that in addition to 3, hemiformals of 3 [e.g., (HBCH2),PCH20CI120H] were also formed.Evidence has now been obtained from variable temperature lH n.m.r. spectra of li in pyridine that the CE12BH groups of 1 and 3 can become magnetically equivalent through chemical exchange. This exchange is an example of a rather rare reorganization involving C-P bonds at quadruply-connected pbosphoeus (4). In a solvent of higher base strength, such as triethylamine, in which the phosphonlum salt is completely neutralized, attack of the liberated formaldehyde at phosphorus of the phosphinle is somewhat slower than in pyridine and is apparently accompanied by attack at oxygen. In Table 1 are summarized the results of a 'H n.m.r. study of the phosphonium salt 1 dissolved in pyridine or triethylamine, either dry or in the presence of D,O. In pyridine, as the temperature was raised from 33", the doublets for 3 and 1, in turn, collapsed to singlets before these merged into the composite singlet at 6 5.13 (Fig. 1) in the range 84-100". The small amount of tris(hydroxymethy1)phosphine oxide (4) which is present was then readily seen. The coalescence was completely reversible with a change in temperature and after cooling the solution from 100" to 33", K,, was about 5 x I V 4 . In pyridine-D,O, the signal for the phosphine 3 was already a singlet at 22". The position of equilibrium (5), judging from the shifts of 1 (6 4.92 at 0"). 3 (6 4.28), and the composite signal in the aqueous medium, appears to be about the same as in neat pyridine.These reversible effects are compatible with chemical exchange averaging of the CH,OH groups of 1 and 3 according to eq. 1. Rever...
