Chirality

Question 1

What is a chiral carbon

Answer 1

A carbon atom that has four different atoms or groups attached to it

Question 2

Is the Chiral carbon symmetric or asymmetric

Answer 2

Asymmetric

Question 3

What do compounds with one chiral carbon exist as

Answer 3

Two optical isomers known as enantiomers which are like mirrored images

Question 4

Describe chemical properties of optical isomers

Answer 4

generally identical, with one exception
Optical isomers interact with biological sensors in different ways

Question 5

Describe physical properties of optical isomers

Answer 5

have identical physical properties, with one exception
Isomers differ in their ability to rotate the plane of polarised light

Question 6

What is one major difference between enantiomers

Answer 6

One enantiomer rotates plane polarised light in a clockwise manner and the other in an anticlockwise fashion

Question 7

How can you determine identity of optical isomers

Answer 7

The rotation of plane polarised light can be used to determine the identity of an optical isomer of a single substance

Question 8

How can you identify the identity of optical isomers

Answer 8

The rotation of plane polarised light

Question 9

What is a racemix / racemate mixture

Answer 9

mixture containing equal amounts of each enantiomer

Question 10

Why is a racemic mixture optically inactive

Answer 10

the enantiomers will cancel out each others effect

This means that the plane of polarised light will not change

Question 11

What does separating an enantiomer give you

Answer 11

enantiopure, it contains only one enantiomer

Question 12

Why are some drugs sold as racemic mixtures

Answer 12

This separation process is very expensive and time consuming, so for many drugs it is not worthwhile, even though only half the of the drug is pharmacologically active

Question 13

how many step is SN1 and SN2

Answer 13

SN1 - two step
SN2 - one step

Question 13

explain SN1 mechanism

Answer 13

Step 1: C-X bond breaks heterolytically and halogen leaves the halogenoalkane as X- ion

Forming a trigonal planar, tertiary carbocation

Step 2: Tertiary carbocation attacked by nucleophile forming racemic mixture

Question 14

what does Sn1 reaction form and why

Answer 14

racemic mixture as nucleophile is able to attack from either side of the planar carbocation, which results in the formation of a racemic mixture

Question 15

explain Sn2 reaction

Answer 15

nucleophile donates a pair of electrons to the δ+ carbon atom of the halogenoalkane to form a new bond

At the same time, the C-X bond is breaking and the halogen (X) takes both electrons in the bond
The halogen leaves the halogenoalkane as an X- ion

Question 16

using bromoethane and hydroxide ion nucleophile as an example

how does the bromine atom cause steric hindrance?

Answer 16

the hydroxide ion nucleophile can only attack from the opposite side of the C-Br bond

Question 17

how does a molecule undergo inversion of configuration in Sn2 reaction
(like umbrella turning inside out)
using bromoethane and hydroxide ion nucleophile as an example

Answer 17

As the C-OH bond forms, the C-Br bond breaks causing the bromine atom to leave as a bromide ion