JEE Main 2014 · 11 Apr · Shift 1 · Chemistry Q52

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ChemistrySingle correct+4 / -1Question 52 of 90

The reagent needed for converting $\ce{Ph-C#C-Ph}$ into trans-stilbene ( $\ce{PhCH=CHPh}$ , the two Ph groups on opposite sides of the double bond) is :

Diphenylacetylene → trans-stilbene (H and Ph on each alkene carbon, the Ph groups trans).

Cat. Hydrogenation

\ce{H2}

/Lindlar Cat.

\ce{Li/NH3}

\ce{LiAlH4}

Answer and worked solution

Official answer: C

Dissolving-metal reduction ( $\ce{Li/NH3}$ ) of an alkyne gives the trans-alkene. Lindlar's catalyst gives cis, and full hydrogenation gives the alkane.

Topics:Alkynes Geometrical isomerism

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JEE Main 2014 · 11 Apr · Shift 1, Chemistry question 52