C O M M U N I C A T I O N S
Table 1. Butadiene Hydrocyanation in Dioxane with ACH as HCN
Supporting Information). Careful adjustment of HCN dosation to
the rate of hydrocyanation and isomerization could indeed lead to
an improved one-step process for 3PN. For comparison we applied
typical diphosphite and diphosphine ligands under identical condi-
tions (see Supporting Information). These hydrocyanation reactions
led to a low selectivity for 3PN. Moreover, these systems show a
lower activity in the isomerization of 2M3BN to 3PN, which is in
agreement with the proposed catalytic cycle.
In conclusion, we developed an improved route for a triptycene-
based diphosphine. The coordination behavior of this ligand toward
Pt(II) and Ni(0) was investigated and the X-ray crystal structure of
the complex cis-(5)PtCl2 was determined. The (5)Ni(cod) complex
was applied in the hydrocyanation of butadiene, showing excellent
selectivities of up to 98% toward 3PN. Low HCN concentrations
achieved by controlled dosation guarantee both high conversion
and high selectivity, avoiding catalyst deactivation in this one-step
procedure. Thus, robust hydrocyanation catalyst systems with
additional isomerization activity could be the key toward process
intensification.
Sourcea
ratio
S/Ni
ratio
ratio
conversion
(%)
3PN
(%)
time
(h)
entry
(5)/Ni
ACH/butadiene
1b
2
3
4
5
125
125
125
125
125
600
1.0
1.0
1.0
2.0
1.0
1.0
1.2
1.2
1.2
1.2
3.0
1.2
48
59
85
62
21
20
65
5
3
5
5
5
3
97.6
94.8
92
70.5
90.0
6
a Conditions: 0.018 mmol Ni(cod)2, acetonecyanohydrine (ACH) as HCN
source, 90 °C, 2 mL of dioxane. b Reaction performed in toluene (2 mL).
Table 2. Butadiene Hydrocyanation in Dioxane with HCN
Dosation and Direct Additiona
ratio
S/Ni
ratio
conversion
(%)
2M3BN
(%)
3PN
(%)
time
(h)
entry
(5)/Ni
1b
2b
3c
125
300
125
1.0
1.0
1.0
100
100
9
2.4
25.6
58.5
93.3
73.3
41.5
5
5
0.5
Acknowledgment. The authors thank T. Staring for technical
assistance. This work was financially supported (A. L. Spek) by
the Dutch Science foundation (CW-NWO).
a Conditions: 0.018 mmol Ni(cod)2, HCN excess, 90 °C, 2 mL of
dioxane. b Slow HCN dosation (excess) as dioxane solution (13 µmol/min).
c Direct addition of excess HCN.
Supporting Information Available: A listing of all experimental
procedures, cif file, and the crystal data for complex 6. This material
Scheme 2. Proposed Cycle for Butadiene Hydrocyanation and
2M3BN Isomerization
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