Assignment of Organic ChemistrySubmitted to: Madam Tahira

Submitted by: Sidra FahimRoll No. 45

B.S Chemistry (6th semester)Dated: 3rd April 2013

Topic: stereochemistry of 1,4- methyl cyclohexane carboxylic acid:

• It is disubstituted cyclohexane .

Cyclohexane has two types of conformations:1)- Chair form

2)- boat form

Similarly, 1,4-methyl cyclohexane carboxylic acid also has two types of conformations:

• 1)- Chair form:

2)- Boat form:

Its chair form has four types:

i. Axial-axialii. Axial-equatorialiii. Equatorial-axialiv. Equatorial-equatorial

Cis or Trans form:

When COOH group is present at C1 in axial position and CH3 group is present at C4 in axial position then the compound must be trans.

Similar case is present when both these groups are at equatorial position.When COOH group is present at C1 in axial

position and CH3 group is present at C4 in equatorial position then the compound must be cis.

The chair form of cyclohexane is more stable than the boat form because

In boat form there is non-bonded interaction between hydrogens which makes it unstable.

There are some points which we are studied in this compound:

I. ChiralityII. Optical activityIII. Element of symmetryIV. Hydrogen bonding

I. Chirality:

A chiral molecule is that in which carbon atom is bonded to four different atoms.In 4-methyl cyclohexane carboxylic acid, there is no chiral carbon. So, this compound is achiral.

II. Optical activity:

The property of a compound of rotating the plane of polarization is called optical activity.Optical isomerism is not possible in 4-methyl cyclohexane carboxylic acid because it has a plane of symmetry passing through the substituted carbons.

III. Element of symmetry:

There are three main types of elements of symmetry:a) Plane of symmetryb) Centre of symmetryc) Axis of symmetry if there is any elements of symmetry present , the molecule will be achiral and will not show optical activity. As in this molecule, plane of symmetry is present. so, it is achiral molecule.

IV. Hydrogen Bonding:

As in this molecule, COOH group and CH3 group are present. There may be hydrogen bonding present between these two groups but it is not possible because both groups are present at larger distances 1st at C1 and 2nd at C4. So intra-hydrogen bonding is impossible in it.