Question

(2.) Draw structures corresponding to the following names: a) (4E)-2,4-dimehyl-1,4-hexadiene b) Cis-3,3-dimethyl-4-propyl-1,5-octadiene c) 4-methyl-1,2-pentadiene d) (3E,5Z)-2,6-dimethyl-1,3,5,7-octatetraene e) 3-butyl-2-heptene f) Trans-2,2,5,5-tetramethyl-3-hexene
please explain fully. also I am confused why there are numbers in with E and Z

Answer 1

E is for the configuration of the double bond. It indicates that the double bond is in trans configuration where the two larger groups at the ends of the double bond are at opposite sides of the double bond.

Z indicates that the double is in cis form where the two larger groups at the ends of the double bond lie at the same side of the double bond.

The number associated with E/Z denotes the position of the double bond in the principal chain.

E: * N obo con = large groups at the ends of double bond Here large groups are at opposite sides of the double bond. So, it is in E form. 2: A Large side groups at the ends of of the double bond double bond are at same So, et a Z alkene.

a) (46)-2,4-dimethyl-1,4-hexacliene E is for trans alkene where the large groups at the ends of the double bond die at opposite sides of the double bond. 1,4-henadiene = 6 Carbon atoms with double H bonds at Cl and C4 4E = double bond at C4 is trans 2,4-dimethyl = two methyl substituents at C2 and C4. Now, the structure is:

1. Ce-3.3-dimethyl-4-propy i ☺ VI b) Cis-3, 3-dimethyl-4-propyl-1,5-octadiene two methyl double substituents 8 carbon atoms chain bond in at C3 substituent with two double cis at cu bonds at cl and C5. Propyl Structure: 4-methyl-1,2-pentadiene 5 carbon atoms chain methyl group with double bonds at at C4 C/ and C2 Streckone : alacak Structure: d) (36,52) -2,6-dimethyl-1,3,5,7-octatetraene e double bond at c3 is trans two methyl groups at ca and C6 8 carbon chain with double bonds at CI, C3, C5 and 67 groups are at same and that at 15 is cis z signifies that the lange - side of double bond. Structure:

e 3- butyl-3-heptene, 7 carbon chain with butyl poup - at c3 double bond at C2 Structive: Structure a Isans = 2,2,5, s-tetramethyl-3-hexene 4 methyl groups 6 carbon chain each at C2, (2,05 with double Double bond and CS bond at C3 is trans Structine: