Question

The interaction of elemental sulfur with Grignard reagent gives __________
A.${H_2}S$ gas
B.Mercaptan
C.Thioalcohol
D.$R - S - OH$

Answer 1

The elemental sulfur is the pure sulfur i.e. S and Grignard reagent is the organometallic reagent used in organic chemistry with general formula $R - Mg - X$ and in this X = halogen. It combines with sulfur to give a compound and in this reaction magnesium goes out when the final product is acidic hydrolyzed .

Complete step-by-step answer: In the given question, the elemental sulfur i.n. pure form of sulfur is reacted with Grignard reagent and we have to find out the expected product from the reaction.
Grignard reagent is an organometallic compound with general formula $R - Mg - X$ in which $R$= alkyl group and $X$= halogen and this reagent is generally prepared by reaction of alkyl halide with magnesium metal which ultimately gives out Grignard reagent.
Now when this reagent is reacted with sulfur, the reaction occurs is as follows: -
$R - Mg - X{\text{ }} + {\text{ }}S{\text{ }}\xrightarrow{{dryether}}R - S - Mg - X{\text{ }}\xrightarrow{{{H^ + }}}R - SH{\text{ }}\left( {mercaptan} \right)$
This Grignard reagent reacts in the presence of dry ether and it forms an intermediate which on acidic hydrolysis gives our final compound i.e. Mercaptan which is also called as thioalcohol.
So, in the given options B is mercaptan which is the compound formed in the reaction above and the option C is thioalcohol which is general name given to the $- SH$ group because $- OH$ is called as alcohol and in this oxygen is replaced with sulfur and therefore it is called as thioalcohol.

So, the correct answers of this question are B and C i.e. Mercaptan and Thioalcohol.

Note: Grignard reagent is the most important reagent which is used in organic chemistry and helps us a lot in conversion of compound and functional groups. For example, when Grignard reagent reacts with aldehyde compound it forms alcohol compound and with ketone compound it forms tertiary alcohol. Similarly, there are a number of reactions of Grignard reagent which should be known to answer such similar types of questions.