← +52 JQ T © ΑΙ SECTION C (SEEN Part of Exam Paper) Answer ONE question only in this section (Each question is worth 20 marks) 5. Answer ALL parts of this question. (a) The following QSAR equation was derived for the pesticide activity of structure Q5(a). Explain what the various terms mean and whether the equation is a valid one. Identify what kind of substituents would be best for activity. (b) (c) Q5(a) log 1/C = 1.08LogP + 2.41 σx-0.072 MRX +5.25 (n=16, r² = 0.840, s = 0.59) (10 marks) A QSAR equation for the anticonvulsant (Q5(b)) was derived as follows: Q5(b) log 1/C = 0.92 TTX - 0.34 TTX² + 3.18 (n=15, r² = 0.902, s = 0.09, πTo = 1.35) What conclusions can you draw from this equation in terms of the influence of the substituent hydrophobicity constant TT ? Which of the following X substituents would you expect to have the greatest activity CF3 (π 1.16), H (T = 0.00), or CH3 (πT = 0.52),? (5 marks) The following QSAR equation is related to the mutagenic activity of a series of nitrosoamines; log 1/ C = 0.92 πT +2.080 - 3.26 (n = 12, r² = 0.794, s = 0.314). What sort of substituent is likely to result in high mutagenic activity? Suggest 2 substituents that meet this criterion. (5 marks) Continued... 5