Question

Table 1: AM1 Energies of the carbocations formed from nitration of the named compound (kcal/mol)

	ortho	meta	para
Toluene (S = CH3)	221.74	224.49	219.04
Phenol (S = OH)	179.10	193.32	177.44
Trifluorotoluene (S = CF3)	95.17	90.06	93.56
Methyl benzoate (S = CO2CH3)	160.00	159.34	159.34

Using the table answer the following questions.

1 a. The carbocation intermediates are good models of the transition states for the corresponding aromatic reactions. When looking at the transition state energy of two reactions, does the comparison tell you which reaction is faster (kinetic data), or does it tell you which reaction gives a more stable product (thermodynamic data)?

1 b. According to your calculations, which substituent(s) (-CH₃, -OH, -CF₃, or -COOCH₃) direct attack to the meta position and which substituent(s) direct attack to the ortho/para positions? How did you decide?

1 c. What are the general characteristics of an ortho/para director? What are the general characteristics of a meta director?

1 d. According to your calculations, of the two substituents that are ortho/para directors, which has the stronger preference for ortho/para versus meta? How did you decide?

1 e.. According to your calculations, for the two substituents that are ortho/para directors, which position (ortho versus para) is preferred? Propose what effect is causing one position (ortho or para) to be preferred over the other?

1 f. Based on the Spartan data, the major product obtained for nitration of methyl benzoate is predicted to be what?

Answer 1

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