Trialkyl Phosphite nile 53 R # CHB In contrast with the spectrum of trin-propyl phosphite where the ion m/e 45 occurs with low intensity, the spectra of tri-isopropyl phosphite, di-isopropyl hydrogenphosphonate and di-isopropyl methylphosphonate show rearrangement ions of high intensity at mle 45. This high intensity ion a t m/e 45 for di-isopropyl hydrogenphosphonate was not reported by Harless ( I ) .
ion m/e 53 (H4P08)in the dialkyl hydrogenphosphonates and trialkyl phos~ ~ h i t ecan s be written in a number of forms. The suggestion by blcLafferty (4) that the ion H4P04in the phosphates is stabilized by resonance between four equivalent structures involving pentavalent phosphorus would account for the stability of the ions R’H3POa (R’=H, dialkyl hydrogenphosphonates and trialkyl phosphites; R’= alkyl, dialkyl alkylphosphonates; R’=OH, trialkyl phosphates), found with strong intensity in all of the organophosphorus esters reported so far. This ion wvoiild then lie represrntrd
In the case of the trialkyl phosphatse a fourth form participates in the resonance hybrid. Similar structures involving pentavalent phosphorus and trivalent oxygen could be written for the ions HP(OR),(OH) and HP(OR)(OH)z found in the trialkyl phosphite spectra. Ions of the type POH(OR), P(OH)2, and P(OR)Z containing trivalent phosphorus ran be represented
\
0-R R
/
DISCUSSION
‘\ =
0L-R
n k y l or TI
0-H
The structure of the ion m/e 99 (Hc POc) in the trialkyl pho.qphates and the LITERATURE CITED
Table II.
Dissociation of Esters of Phosphonic Acids, R’PO(OR)2
R’gH : R i C x H i nz/e RI R’PO(0R )2 R’PO(OR)(OX) R’P(OR)(OH )2 R’PO(OR)(OH) R‘PO(OX)(OH) R’PO(0R) R’P(0H)a R‘PO(0H)
I66 151a
125 124 109b
...
83 65
