Download Density Functional Theory studies for the ring opening mechanism

Density Functional Theory studies for the ring opening mechanism of 1,2-epoxy2-aryl ethylgembisphosphonate derivatives
Marondedzea E. F., Govendera P. P., Singhb T. & Mbiandaa X.Y.
aDepartment
of Applied Chemistry, University of Johannesburg, Johannesburg, 2028, South Africa;
bDurban University of Technology, Durban, South Africa
Tel: 011 559 6555
[email protected] ; [email protected]; [email protected]; [email protected]
Abstract
Bisphosphonate applications include (but are not limited to), chelating agents in water treatment, anti-tumor
agents (for example, breast cancer therapy), rheumatoid arthritis, osteoporosis, Paget’s disease and bone
scanning [1]. For water treatment purposes, they are normally added to prevent the precipitation of
magnesium or calcium and the effects of other metal ions such as iron that can find their way to the
environment through grey wastewater. This means they can also be used for preventing scale formation in
water cooling systems. Bisphosphonic acids are added to some detergents to counter the effects of hard
water for example etidronic acid [2]. 1,2-Epoxy aryl gembisphosphonates can be used as a starting point
for the synthesis of a variety of gembisphosphonates including amino gembisphosphonates [3]. The
reactivity of epoxides (attributed to the strain on the oxirane ring) is based on the opening of the oxirane
ring (Figure 1) which is dependent on the reaction conditions provided [4].
O OEt
P
H
O
P
OEt
OEt
H
+
NH3
OEt
NH2
O OEt
P OEt
OEt
P
OEt
OH O
O
Figure 1: Epoxide ring opening
Density Functional Theory (DFT) [5] is being employed to theoretically determine the mechanism of the
oxirane ring opening for Tetraethyl 1,2-epoxy-2-phenylbisphosphonate in basic and acidic media.
Simulations are being carried out with the Gaussian 09 software [6] using the generalized gradient
approximation functional BP86 at the 6-31+G(d,p) basis set [6] . The effect of both electron donating and
-withdrawing groups will also be investigated.
Key words: Ring opening, DFT, synthesis, bond.
References
[1]
[2]
[3]
[4]
[5]
[6]
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Parker R. E. and Isaacs N. S., “Mechanisms of Epoxide Reactions,” Chem. Rev., vol. 59, no. 4,
pp. 737–799, 1959.
Young D. C., 2001, COMPUTATIONAL CHEMISTRY A Practical Guide for Applying Techniques
to Real-World Problems, vol. 9, Wiley, New York, pp. 42–213.
http://www.gaussian.com/g_tech/g_ur/k_dft.htm. last accessed: 20-June-2014