Question

The compound having planar molecular configuration is:

• A. Chloroethene
• B. Butenyne
• C. 1-chloroprop-1,2-diene
• D. But-1,2,3-triene

Answer 1

Answer: (A), (D)

Chloroethene and But-1,2,3-triene

Answer 2

1. Chloroethene: Both carbons in chloroethene are sp²-hybridized (as in a typical double bond) leading to a planar structure.

2. 1-chloroprop-1,2-diene: This is an allene derivative. In allene (propadiene) the two π–systems lie in perpendicular planes, so substitution (with Cl) does not force overall planarity.

3. But-1,2,3-triene: This molecule is a cumulene with three cumulated double bonds (four carbon atoms). Cumulenes with an odd number of double bonds (i.e. even number of C atoms) adopt a planar geometry.

4. Butenyne: A compound containing both a double and a triple bond may not be completely planar because the triple bond is linear while the double bond is planar, and the conjugation between them is not sufficient to enforce overall planarity.

Thus the compounds having a planar molecular configuration are Chloroethene and But-1,2,3-triene.