Question

Relate each two of the three (or four) structures above with whether they are enantiomers or diastereomers. USE THE NUMBERS MENTIONNED IN THE BOXES ABOVE TO RELATE BETWEEN THEM. (3 points for each relation, any additional relation will be penalized) Pair of structures (use their numbers) Relationship This one remains blank if it is a meso-compound

Answer 1

1. Yes the compound is meso and plane of symmetry is shown in figure

COOH co Himme ON I 27/17 (Internal mirror plane H H nume CooH COH OH fischer projechon

Meso compounds are those that have at least 2 asymmeteic carbon ( those carbon with all 4 subatituents to be different ). But both 2 asymmnetric carbon have same groups as one another ( as in this question). There must be a plane of symmetry passing through the molecule or the configuration of bothe asymmeteic carbon should be different.

And since as in the given question there are 2 assymeteic carbons and a plane passing through the molecule so it is meso compound.

Ques 2. Isomers are shown below :

Stereoisomers are those compound which have same molecular formula but different arrangement of atoms in space ( the position of atoms can be changed between the following positions: on plane, above plane or below plane). This movement  constitute stereoisomer.

In stereoisomer the R/S configuration changes .

The configuratikn can be given as per CIP rule which is on the basis of atomic mass.

▪︎Higher the atomic mass more will be its priority.

▪︎ if while moving from 1st priority to 2nd and then to 3rd the direction of movement is clockwise then configuration is R. But if the direction is anticlockwise then configuration is S. But this is valid if 4th priority group is below the plane.

▪︎ if 4th priority group is above the plane then configuration reverses. I.e., the clockwise direction will now give S configuration and anticlockwise movement will now give R configuration.

Thus 3 isomer are as shown below with

•1 isomer both Asymmetric carbon have S configuation.

•the 2nd isomer has both carbons R configuration

•and in 3rd isomer there is 1R and 1 S configured carbon ( which is meso).

I somers Cool COOH coor HO H H vo . TO H H coon Coor coon # 04 -Cool coon ® cool Hhhi НpriA11 С Hound Hout Ho muinc Coon 'cooh Coon H OH (a) (6) c) RIS configuration in the structure done justify to somers AS per CIP rule - -OH → 1st priority OoH 2nd 3rd priority priority priority -