ALEXANDRIA
UNIVERSITY
FACULTY OF SCIENCE
M.Sc. Students Chem. 705
Advanced Physical Organic Chemistry
Time Allowed: 60 min.
(Open book exam) 21 March 2020 - TEST Midterm 1-M SC, 21 March -2020
Please write legibly and draw clearly. Marks will be deducted for messy answers.
Please write clearly in black ink or ballpoint pen. Do not use pencil or red colours!
1) a) Write one paragraph on the different steps (only steps) of Hückel molecular
orbital method for the calculation of the energies and shapes of molecular
orbitals of -conjugated systems.
(10 marks)
b) What are the most important kinds of results (Molecular physical
parameters) that can be obtained from Hückel calculations?
(5
marks)
2) Using all notes have been used in the lectures and chapter 4 (Applications of
Molecular Orbital….by F. A. Carroll) answer the following problems form the
mentioned chapter :
(35 marks, (5 marks each))
a) Page 246, Q 4.4 only compound C.
f) Q 4.30
g) Q 4.32.
h) Q 4.34.
b) Q 4.17.
d) Q 4.21.
e) Q 4.29.
3) The results of HMO calculation on Z-pentadienone (1) are given below: (25 marks)
6
5
2
4
3
O1
1






i) Sketch the frontier molecular orbitals on the basis of the calculation.
ii) Assuming that 1 were to react with an electrophile, where is the most likely site of
attack? Compare the Lewis basicity of 1 to that of ethylene.
iii) In terms of , estimate the energy of the lowest electronic excitation of 1.
Is the state likely to be higher or lower than the nstate? Explain in less than three
lines.
iv) Calculate the  bond order of the C2-C3 bond of 1. What is the net charge on O1?
v) Show the most likely product from a Diels-Alder reaction of 1 with 1,3-butadiene. Pay
attention to all relevant aspects of stereo- and regioselectivity.
1