Chemistry Reference
In-Depth Information
Cl
NH
1) NH
3
, CH
2
Cl
2
Me
2
NH, CH
2
Cl
2
PCl
5
Me
2
N
P
NMe
2
Me
2
N
P
NMe
2
2) MeOK, MeOH
NMe
2
NMe
2
Cl
NH
Me
2
N
P
NMe
2
NMe
2
NR
NMe
2
NHR
NMe
2
(3 equiv)
Cl
P
Cl
Me
2
N
P
NN
P
NMe
2
THF
Cl
NMe
2
N
NMe
2
Me
2
N
P
NMe
2
X
NMe
2
THF
KNH
2
, NH
3
NMe
2
NR
NMe
2
Me
2
N
P
NN
P
NMe
2
NMe
2
N
NMe
2
Me
2
N
P
NMe
2
NMe
2
Scheme 5.2
Synthesis of P4
band intensity changes, comparison with the spectra of related compounds and MO
calculations [7]. AUV-Visible spectrophotometric method for the measurement of relative
acidities in heptane was developed and the phosphazene base
t
Bu-P4 was used as the
deprotonating agent. Its protonated form is a good counter ion for the anions of the acids
because it is bulky, has delocalized charge and, therefore, does not have specific interactions
with the anions.
A self-consistent scale of relative acidities in heptane spanning for 3 pKa units was
constructed [8]. A self-consistent spectrophotometric basicity scale of various organic
bases including phosphazenes in acetonitrile was investigated. The span of the scale is
almost 12 pKa units. The scale is anchored to the pKa value of pyridine of 12.33.
Comparison of the basicity data of phenyliminophosphoranes and phenyltetramethylgua-
nidines implies that the P
¼
N bond in the (arylimino)tris(1-pyrrolidinyl)phosphatranes
involves a contribution from the ylidic (zwitterionic) structure analogous to that found in
phosphorus ylides [9]. A series of RN
¼
P(Pyrr)
3
iminophosphoranes (P1 phosphazene),
where R is amino,
-naphthyl- or substituted phenyl group, was prepared and characterized
by other properties.
The pKa values of 12 different synthesized phosphazenes and C
6
H
5
N
a
P(NMe
2
)
3
were
determined in acetonitrile relative to the reference bases using
13
C NMR spectroscopy. The
¼
