Question

5. In 2011, chemists announced the smallest molecular motor designed to date - a single molecule of CH3SCH2CH2CH2CH3 (butyl methyl sulfide) when placed on a smooth copper surface can be induced by an electric current to spin like a top. Provide a synthesis of butyl methyl sulfide from butane and any other necessary compounds. Comment on any reactions produce a mixture of products. Mechanisms for your reactions are not required.

Answer 1

We can synthesize butyl methyl sulfide from butane in three steps:

Step 1: Free radical reaction of butane with chlorine

250° 400°C Cl2 or light CI n-Butane Chlorine 1-Chlorobutane 2-Chlorobutane

Step 2: Reaction of 1-Chlorobutane with thiourea

NH2CI NH2 NH2 H2N n-Butane Na CO3 Thiourea SH

Step 3: Reaction of 1-butanethiol with MeI in the presence of a base.

Na CHI SH Nal 1-Butane thiol Butyi methyl sulfide