Question

​​​​​​​Please answer all two questions and please explain! I'm completely lost at the moment and I'm not sure how to solve it. Please do it step by step if possible.

10. (10 points) Account for the relative product distribution for the radical bromination reaction shown below. (a) Write the hydrogen abstraction step reaction (radical formation), including the transition state, that leads to each product. (b) Match each reaction to the correct reaction coordinate diagram. Draw the reactants on the energy curve, and the appropriate structures present at all points on the energy curves marked by the capital letters. Brz hv Br + 92% 92% 9% 8% B+ B + HBr A# A + HBO P.E. + Br Eact Reaction coordinate Bonus (5 points) Complete the mechanism of the following ozonolysis reaction and provide the final products. w o - no y 0-0 nosan H2C-S-CH3 molozonide ozonide

Answer 1

10) a) Photochemical decomposition of 2,3-dimethyl butane results in the abstraction of protons. As in the given molecule their are only secondary and primary protons this give rise to two possibilities thereby resulting in the formation of a secondary and pimary free radicals respectively.

As secondary free radicals are more stable than the corresponding primary free radical therefore major 92% product is obtained when bromide free radical attacks the secondary free radical, shown below:

(a) ha H Radical formation free 2,3-dibromo butane secondary radical Primary free dical STABLE THAN THE SECONDARY FREE RADICALS ARE MORE PRIMARY FREE RADICALS step - Attack of bromine free radical Br2 h a Bri (Bromide free radical) + H Br y + 8x' — for (92"1.) + HBA MAJOR secondary free radical -Br (81) + HB r + Br MINOR Primary free radical

b) The major product involving secondary free radical is fast and is formed without much expenditure of energy thus the activation energy for it is lowest, hence the reaction coordinate corresponding for both product A and B will be:

- НВт Potential energy HBr +HBO MAJOR Y+ Be Reaction coordinate

Secondary free. A radical Co ** X Primary radical Primary pre free

OZONOLYSIS

Ozone rects with alkene via 1,3- dipolar cycloaddition reaction in which the negatively charged oxygen atom (formed due to resonance) attacks the alkene carbon atom to give the desired molozonide transition state.

• The so formed ozonide is then reacted with CH₃S​​​​​CH₃ molecule.
• Lone pair of electrons of the sulphur atom attacks the oxygen atom in the ozonide results in the shifting of electron density to give propanal as the final product as shown below.

Sup-oi 1,3-cyclo addition reaction Hex-3-ene L Molozonide / slep-02 -CH3 0- O < It cH3 Ozonide CH3 Transition state I FINAL PRODUCT x Propanal + CH3