Protonation of Grignard reagents to give alkanes
Description: Treatment of Grignard reagents with acid leads to alkanes. Alternatively, use of deuterated acids leads to the resulting deuterated compounds.
Notes: X here is a halide (Cl, Br or I). Note that deuterium (D) is a heavy isotope of hydrogen which behaves in a chemically identical fashion.
Notes: Since Grignards are such strong bases, even weak acids like water or alcohols work great. Example 4 shows an example of using this reaction to introduce deuterium into a molecule (deuterium is just the heavy isotope of hydrogen).
Mechanism: Addition of acid (in this case just water) leads to protonation of the carbon (Step 1, arrows A and B).
Notes: Instead of water, any reasonably acidic species could have been used here, such as an alcohol, carboxylic acid, acid, etc.