The compound shown is 1-chloro-3-methylpent-1-ene drawn without stereochemistry. Counting geometrical and optical isomers together, how many stereoisomers does it have? Give an integer.

Numerical answer type.

Answer: 4

The

C X_{1} = C X_{2}

bond has

Cl

and

H

on C1 and

H

and C3 on C2, so it can be

E

Z

. C3 carries

H

CH X_{3}

C X_{2} H X_{5}

and the vinyl chain, so it is a stereocentre,

R

S

. There is no symmetry to make any combination coincide, so the total is

2 \times 2 = 4

stereoisomers (two pairs of enantiomers).