Question

OH vo: COOH H CH NH2 --CH₃ HN norepinephrine alarine Нос H HC CH3 H носон tartaric add CH2 daydrocarvone

Answer 1

In order to find out the correct configuration at a chiral carbon we should first give priorities to the atoms or groups around the carbon atom.

The priority of a group depends on cahn-ingold-prelog rules.

The group attached to the carbon through the biggest atom will be the first in order and lowest group will be of least priority.

A R-configuration 애 A OH | I CANH₂ = Ar clockwise rotation Lowest pridety group u 14 (H) projected back.. inch NH₂ So, R-configuration. – CH-NH₂ – Ar – H. Ho Pridity order – oH B. S- configuration. B cooh COOH CECH, 3 0 *3 HN clockwise rotation to the front & and lowest priority group (H) projected hence, it is 's-configuration. c. R-configuration. CO. It cott of it C#(04)(CO2) Нене olt co₂H OH clockwise rotation back and hence and it is towest priority Ronfiguration group (H) Projedec at & CH3 IN clockwise, Hydrogen projected front- S-configuration And from CHA Anti-clockwise Hydrogen projector Backward s-configuration,

A. R-configuration

Priority order 1 -OH as Oxygen is the biggest atom directly attached to A Carbon.

Priority order 2 -CH2NH2 as this carbon is attached to Nitrogen which is bigger than carbon.

Priority order 3 -C=C of aromatic ring. A double bonded carbon equals to carbon attached to two other carbon atoms and hence it is given a third priority.

The priority order is clockwise direction with lowest priority order group (H) directed backwards and hence it is R-configuration at A.

B. S-configuration

Priority order 1 -NH2 as Nitrogen atom is the biggest atom directly attached to B carbon.

Priority order 2 -COOH as carbon atom is attached to the oxygen atom.

Priority order 3 -CH3 as carbon is attached to three smaller hydrogen atoms.

The priority order is clockwise direction with lowest priority order group (H) directed front and hence it is S-configuration at B.

C. R-configuration

Priority order 1 -OH as Oxygen is the biggest atom directly attached to C Carbon.

Priority order 2 -COOH as carbon atom is attached to the two oxygen atoms.

Priority order 3 -CH(OH)(COOH). The carbon atom is attached to one oxygen and one carbon atom but in COOH carbon is attached directly to two oxygen atoms and hence this group is given the third priority.

The priority order is clockwise direction with lowest priority order group (H) directed backwards and hence it is R-configuration at A.

D. S-configuration

Priority order 1 H3C-C=CH2 , the middle carbon in this group is considered to be attached to three carbon atom as there is the presence of a double bond and hence is given the first priority order.

Priority order 2 -CH2(CO)CH2- , carbon chain continues with a carbonyl group at the second position of the group.

Priority order 3 -CH2CH2CH2- , as this is the group that continues with the smallest atoms, it is given the third priority.

The priority order is clockwise direction with lowest priority order group (H) directed front and hence it is S-configuration at B.

E - S-configuration

Likewise, For E carbon also, the priority orders are given to the functional groups which gives anti-clockwise order with hydrogen projected backwards. Thus the configuration is S at E.

Compare this explanation with the uploaded image.