What is the major organic product that results when 3-heptyne is subjected to excess hydrogen and a platinum catalyst? A) 2-heptyne
B) (Z) -2-heptene
C) (Z)-3-heptene
D) (E)-3-heptene
E) heptane

E) heptane .

Explanation:

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In this case, referring to the hydrogenation of alkynes over platinum catalyst in excess hydrogen, it's been demonstrated that such process occurs upon two steps; first hydrogenation to alkene and second the hydrogenation to alkane:

CH₃-CH₂-C≡C-CH₂-CH₂-CH₃ + H₂ → CH₃-CH₂-CH=CH-CH₂-CH₂-CH₃

CH₃-CH₂-CH=CH-CH₂-CH₂-CH₃ + H₂ → CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Therefore, the product is E) heptane .

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