Which of the following compounds can in principle be isolated in optically active form at room temperature? Select all valid choices.
a. trans-1,3-dimethylcyclohexane
b. cis-1-ethyl-3-methylcyclohexane
c. 1,1-dimethylcyclohexane
d. cis-1,4-dimethylcyclohexane
The answer was A and B
Can confirm, it's definitely A and B:
trans-1,3-dimethylcyclohexane
and
cis-1-ethyl-3-methylcyclohexane
Well, let's see which compounds can put on their fancy optical bowties and be optically active at room temperature.
a. trans-1,3-dimethylcyclohexane: Sorry, this compound doesn't feel like standing out in a crowd, so it's not optically active.
b. cis-1-ethyl-3-methylcyclohexane: Ah, look at this compound, ready to shake things up! It has different groups on each side, so it can be optically active.
c. 1,1-dimethylcyclohexane: This compound is just too symmetrical for its own good. It's not optically active – too bad!
d. cis-1,4-dimethylcyclohexane: Nope, this compound also lacks the necessary asymmetry to be optically active.
So, the valid choice is b. cis-1-ethyl-3-methylcyclohexane. It's the life of the party when it comes to optical activity!
To determine which of the compounds can be isolated in optically active form at room temperature, we need to consider the presence of a chiral center. A chiral center is an atom, typically a carbon atom, which is attached to four different groups or ligands. Compounds possessing a chiral center can exist as two enantiomers, which are mirror images of each other and differ in their optical activity.
Let's analyze each compound:
a. trans-1,3-dimethylcyclohexane: This compound does not have a chiral center since the two methyl groups are identical. Thus, it cannot exist as enantiomers.
b. cis-1-ethyl-3-methylcyclohexane: Similar to compound a, this compound also lacks a chiral center, making it impossible to isolate in optically active form.
c. 1,1-dimethylcyclohexane: In this compound, the two methyl groups are connected to the same carbon atom. Consequently, it does not have a chiral center and cannot be isolated as enantiomers.
d. cis-1,4-dimethylcyclohexane: This compound features a chiral center, the carbon atom to which the two methyl groups are attached. Since the two methyl groups are different, cis-1,4-dimethylcyclohexane can exist as two enantiomers. Therefore, it can be isolated in optically active form at room temperature.
In conclusion, the only valid choice that can be isolated in optically active form at room temperature is d. cis-1,4-dimethylcyclohexane.