Many primary amines, RNH2, where R is a carbon-containing fragment such as CH3, CH3CH2, and so on, undergo reactions where the transition state is tetrahedral. (b) What kind of reactant with a primary amine can produce a tetrahedral intermediate?

The rates of many atmospheric reactions are accelerated by the absorption of light by one of the reactants. For example, consider the reaction between methane and chlorine to produce methyl chloride and hydrogen chloride:

Reaction 1: CH₄(g) + Cl₂(g) → CH₃Cl(g) + HCl(g)

This reaction is very slow in the absence of light. However, Cl₂(g) can absorb light to form Cl atoms:

Reaction 2: Cl₂(g) + hv → 2 Cl(g)

Once the Cl atoms are generated, they can catalyze the reaction of CH₄ and Cl₂, according to the following proposed mechanism:

Reaction 3: CH₄(g) + Cl(g) → CH₃(g) + HCl(g)

Reaction 4: CH₃(g) + Cl₂(g) → CH₃Cl(g) + Cl(g)

The enthalpy changes and activation energies for these two reactions are tabulated as follows:

Reaction ΔH° (kJ/mol) E_a (kJ/mol)

3 +4 17

4 -109 4 

(b) By using the data tabulated here, sketch a quantitative energy profile for the catalyzed reaction represented by reactions 3 and 4.

Many primary amines, RNH₂, where R is a carboncontaining fragment such as CH₃, CH₃CH₂, and so on, undergo reactions where the transition state is tetrahedral. (a) Draw a hybrid orbital picture to visualize the bonding at the nitrogen in a primary amine (just use a C atom for 'R').

The mechanism for the oxidation of HBr by O₂ to form 2 H₂O and Br₂ is shown in Exercise 14.74. (c) Draw a plausible Lewis structure for the intermediate HOOBr. To what familiar compound of hydrogen and oxygen does it appear similar?