Chiral Carbons

Carbon attached for four different things (groups or atoms, etc.)

This includes being bonded to four carbons, as long as each of those carbons is bonded to a different group (i.e., isopropyl and butyl)

Chiral carbon definition

They display a new type of isomerism; you can arrange the bonds in two different ways:

(1) R isomer

(2) S isomer

What's important about chiral carbons?

These are constitutional isomers, where you snap off a carbon and attach it to somewhere else

What type of isomerism separates, say, a butane from an isopropyl?

You need a 3D picture of the molecule

What do you need to figure out if its R or S?

Yes

Does every chiral carbon do this?

The one bonded to the chlorine only

Which of the carbon in this molecule is chiral?

None! The center carbon has ethyl groups on either side

Which carbons are chiral?

The one bonded to the chlorine only

Which carbons are chiral?

None! Carbon bonded to two chlorines has, well, two chlorines. So none

How many chiral carbons?

Two! Each of the two carbons bonded to chlorines are chiral

How many chiral carbons?

Immediately dismiss all those with two hydrogens

There is one, the one bonded to the alcohol. The one bonded to the carbonyl group is not bonded to four things!

How many chiral carbons?

sp3

Hybridization of chiral carbons

Two; one bonded to OH and one bonded to Cl

How many chiral carbons?

Only one; the one bonded to the methyl group

How many chiral carbons?

None

How many chiral carbons?

(1) Cross off ones with two or more hydrogens

(2) For the remaining carbons, look at the carbons on either side of the potential chiral carbon in pairs; if they are identical, proceed to next pair on either side, and so on, until you reach the end and once you get around the ring without identifying a difference, it is not chiral

How to determine chiral carbons in ring

None

How many chiral carbons?

One; the carbon bonded to the chlorine.

The one bonded to the two methyl is...well, bonded to two methyls so not chiral

How many chiral carbons?

None; benzene rings have double bonds so cannot be chiral, and the other two have two many hydrogens

How many chiral carbons?

Yes, but the chiral carbon(s) must be on a side chain

Can aromatic compounds have chiral carbons?

Four:

(1) One bonded to chlorine

(2) One bonded to isopropyl

(3) One bonded to sec-butyl

(4) First carbon in the sec-butyl that is directly bonded to the ring

Number of chiral carbons?!

NOTE: This is harder than any question on an exam. This is cholesterol.

There are eight

Number of chiral carbons?!

(1) The number of isomers is 2^(number of chiral carbons)

How do you determine the number of isomers resulting from the number of chiral carbons?