Methyl 3-cyanopropanoate, $NC - CH X_{2} CH X_{2} - COOCH X_{3}$ , is reduced with excess $LiAlH X_{4}$ followed by aqueous work-up. Count only hydride ions delivered to carbon atoms of the substrate (the work-up protons are not counted). The product and the number of hydride equivalents consumed per molecule are

Answer: C

The nitrile

C \equiv N

accepts two

H X^{-}

to become

CH X_{2} NH X_{2}

. The ester takes two

H X^{-}

as well: the first gives the aldehyde after loss of methoxide, the second gives the alkoxide of the primary alcohol. Total

= 2 + 2 = 4

hydride equivalents, product

H X_{2} N - CH X_{2} CH X_{2} CH X_{2} - CH X_{2} OH