Question

How many stereoisomers are possible for each of the following structures? Draw them, and name each by the R-S and E-Z conventions

a) 4-methyl-2,5-heptadiene

b) 1,2,5-trichloro-3-hexene

Answer 1

This forum does not accommodate drawings.

Answer 2

You could use S.M.I.L.E.S.
(Simplified Molecular-Input Line-Entry System)

CC=C(C)C=CC
4-methyl-2,5-heptadiene has two points of E/Z isomerism--the double bond--and one point for R/S isomerism-the central carbon.

When both bonds have the same isomerism the central carbon is symmetric.

When the bonds have different isomerism, the central carbon is chiral.

That's four stereoisomers.

C\C=C/C(C)\C=C/C
Z,Z-4-methyl-2,5-heptadiene

C/C=C/C(C)\C=C\C
E,E-4-methyl-2,5-heptadiene

C\C=C/[C@@H](C)\C=C\C
R,Z,E-4-methyl-2,5-heptadiene

C\C=C\[C@@H](C)\C=C/C
S,E,Z-4-methyl-2,5-heptadiene