Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Write the total number of geometrical isomers possible for :
1. CH3 - CH = CH - CH2CH2CH3
2. CH3 - CH = CH - CH = CH2
3. CH3 - CH = CH - CH = CH - CH2CH3
4. Cl - CH = CH - CH = CH - Cl
5. CH3 - CH = CH - CH = CH - CH = CH2
6. C6H5 - CH = CH - CH = CH - C6H5
7. 
8. 
9. CH3 - CH = CH - Br
10. C6H5 - CH = CH - COOH
11. CH3 - CH = CH - CH = CH - Br
12. CH3 - CH = CH - CH = CH - CH = CH - CH3
Options:
Answer:
Solution:
1. Pent-2-ene : one stereogenic double bond : 2.
2. Penta-1,3-diene : only C-3=C-4 is stereogenic (terminal CH2 has two H) : 2.
3. Hepta-2,4-diene : two stereogenic double bonds, unsymmetrical molecule : 2 x 2 = 4.
4. 1,4-Dichlorobuta-1,3-diene : symmetric molecule, (E,Z) = (Z,E) : 3.
5. Hepta-1,3,5-triene : two stereogenic double bonds (the terminal CH2 is not), unsymmetrical : 4.
6. 1,4-Diphenylbuta-1,3-diene : symmetric : 3.
7. 1,2-Dimethylcyclopropane : cis and trans : 2.
8. 1,2,3-Trichlorocyclopropane : all-cis and (two up, one down) : 2.
9. 1-Bromopropene : 2.
10. Cinnamic acid : 2.
11. CH3-CH=CH-CH=CH-Br (1-bromopenta-1,3-diene) : two stereogenic double bonds, unsymmetrical molecule : 4.
12. Octa-2,4,6-triene : three stereogenic double bonds, symmetric molecule : 6.
Ans. 1: 2 2: 2 3: 4 4: 3 5: 4 6: 3 7: 2 8: 2 9: 2 10: 2 11: 4 12: 6
