Outline an efficient synthesis of each of the following compounds from the indicated start...

Outline an efficient synthesis of each of the following compounds from the indicated starting material and any necessary organic or inorganic reagents:

(a) Isobutyl iodide from isobutyl chloride

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(b) Isopropyl azide from isopropyl alcohol

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(c) (S)-sec-Butyl azide from (R)-sec-butyl alcohol

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(d)