Activation energy with amines

Ab initio calculations on (39) estimate activation energies of amine rotation and ring inversion (39a) and (39b) to be 17.1 and 17.3 kcal mol-1, respectively, which is in good agreement with values derived from NMR experiments (94JA5167). 

Calculate activation energies for Sn2 reactions of ammonia and trimethylamine with methyl iodide via transition states ammonia+methyl iodide and trimethyl-amine+methyl iodide, respectively. Is attack by ammonia or trimethylamine more facile Rationalize your observation by comparing electrostatic potential maps for the two transition states. Which transition state requires more charge separation Is this also the higher-energy transition state ... 

The activation energy of substitution of an unactivated aromatic halide (e.g., fiuorobenzene and 2-chloronaphthalene ) is over 30 kcal while that of activated compounds is 5-20 kcal. For the tabulated reactions (Tables II-VIII) with alkoxide and with primary, secondary, or tertiary amines, resonance activation (cf. 278 and 279) by ortho or para nitrogens is found to be greater than inductive activation (cf. 251). This relation is qualitatively demonstrated in... 

Table XIV, line 3). The rates are equal (only at 20°) due to a large, compensating difference between the entropies of activation. In piperidino-dechlorination, 4-chloroquinoline (Table XI, line 3) has a higher and a lower rate (by about 200-fold at 20°) than 1-chloroisoquinoline (Table XIV, line 1). This reversal of reactivity and of the relationship of the activation energies is attributed to the factors in amination reactions mentioned above. The relative reactivity of the chloro groups in 2,4-dichloroquinoline with methanolic methoxide is given as a 2 1 rate ratio of 4- to 2-displacement. 

Of all the solvated electrons, eh is the most reactive several thousand of its reactions have been measured and, in many cases, activation energies, the effects of pH, and so forth, determined (Anbar and Neta, 1965 Anbar et al, 1973 Ross, 1975 CRC Handbook, 1991). Relatively few reactions of eamhave been studied because of its low reactivity. Rates of reactions of the solvated electron with certain scavengers are also available in alcohols, amines, and ethers. 

There are not so many data on peroxyl radical reactions with amines. Therefore, the values of activation energy and rate constants of reactions of H02 radical with series of amines were calculated using the IPM model (see Chapter 4). The following parameters were used for calculation [4,26]. 

Activation Energies, Rate Constants, and Contribution Enthalpy in Activation Energy for Peroxyl Radical Reactions with Amines, Calculated by IPM Method (See Chapter 6)... 

According to these parameters, the activation energy of the peroxyl radical reaction with aromatic amine can be calculated using the reaction enthalpy by the equation [54]... 

The values of rate constants, activation energies, and geometric parameters of secondary alkyl peroxyl radical reaction with several aromatic amines are presented in Table 15.7. 

Enthalpies, Activation Energies, Rate Constants, and Geometric Parameters of TS of Reaction R02 with Aromatic Amines Calculated by Equations (15.13)—(15.15)... 

Let us compare the rate constants and activation energies of, sec-R02 with phenol and aromatic amine with close reaction enthalpies. 

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