Question

7). Consider the structure for 2,4-dichlorohexane, CH-CH(CI)CH-CH(CI)CH CH. A) (16 pts) Draw all four possible stereoisomers in BOTH the wedge/hash (sawhorse) format as well as Fischer projections. Each box is expected to contain the same stereoisomer. B) (4 pts) CIRCLE the (29,45)-2,4-dichlorohexane isomer. Put a BOX around its enantiomer. C) (5 pts) Which one(s) of the several diastereomers can be separated using Thin Layer Chromatography? 1. all four stereoisomers can be separated 2. The pair (2R,4S) and (2R,4R) can be separated from the pair (2S,4R) and (2S,4S) 3. The pair (2R, 4R) and (2S,4S) can be separated from the pair (2S,4R) and (20,4S) 4. (2R,4S) can be separated from (2S,4R), and those can be separated from the pair (2S,4S) and (2R.4R) 5. none of these stereoisomers can be separated from the others

Answer 1

7A.

To convert dash-wedge to Fischer, Wedge group in Left side and dsashed one in right side To convert Fischer to sawhorse, Bottom carbon does not change but upper on groups Left become right Fishcher Dash-Wedge SawHorse CIH CI HH H SH (2R,45)-2,4-dichlorohexane H CI VE V (28,4S)-2,4-dichlorohexane CH CI H- S CI w - c_SH (2S,4S)-2,4-dichlorohexane CI H (2S,4S)-2,4-dichlorohexane VRH o iš FR) a Hw (2R,4R)-2,4-dichlorohexane H CI (21,4R)-2,4-dichlorohexane Left Right Left H Right |S_C1 iii H-TH HR (2S,4R)-2,4-dichlorohexane CI H Right (2S,4R)-2,4-dichlorohexane Left

7B.

Enatiomers are non-supper impossible mirror images. In generaaly, opposite configurations are enatiomers. R and S are enantiomers. The following are Enatiomers (Both circles and Both Boxes ) Fishcher SawHorse CIH Dash-Wedge CI HCI H- y C—SH V (2R,45)-2,4-dichlorohexane H CI (21,4S)-2,4-dichlorohexane CI H-S CI H- H C—SH ww IIÓ (2S,4S)-2,4-dichlorohexane CI H (2S,4S)-2,4-dichlorohexane Enantiomers H CIH 1 ci CR H oii FR) a Hw (2R,4R)-2,4-dichlorohexane (2R,4R)-2,4-dichlorohexane Left Right HP CI H-FH HRCI (2S,4R)-2,4-dichlorohexane C Left H Right (2S,4R)-2,4-dichlorohexane

7 C.

Diastereomers have different physical properties so we can easily separate out by using TLC.

1. Out of 4 stereo isomers, two pairs are enentiomers and two pairs are Diastereomers. Hence, TLC can not use to separate out.

2. The provided stereo isomer pairs are Diastereomers . Hence, we can easily separate out by using TLC.

3. The first pair is enentiomers but second pair is Diastereomer. So we can not separate out by using TLC.

4. The first pair is Diastereomer. but second pair is enentiomers. So we can not separate out by using TLC.

Therefore, the correct option is 2.