Chirality

A chiral molecule has no internal plane of symmetry and has a non-superimposable mirror image. No matter how you turn it, it will never be the same as its mirror image. On the contrary, achiral molecules have identical and superimposable mirror images.

Conformations

Conformations are 3-dimensional shapes that can be taken by a molecule by rotating about single bonds.

• In the planar conformation, everything is eclipsed. In an eclipsed conformation, the bonds have dihedral angles of zero degrees. This maximizes the energy and leads to instability. Steric hindrance of eclipsing interactions also lead to torsional strain or the resistance to rotation about a single bond.
• In the chair conformation, everything is staggered. In a staggered conformation, the bonds have dihedral angles of 60 degrees. This minimizes the energy and thus leads to more stability.
• All the conformations in between are partially eclipsed.
• The Boat conformation has Flagpole interactions because axial groups attached to the head and tail of the boat clash.
• The Twist-boat conformation lessens these Flagpole interactions in addition to reducing the number of eclipsed interactions.

Organic Nomenclature

The IUPAC (International Union of Pure and Applied Chemistry) system of naming is a set of logical rules used to eliminate problems caused by arbitrary naming. It's most important features include:

1. The root or base which indicates the major chain or ring of carbon atoms found in the structure
2. A suffix or other elements which designates the functional groups present in the compound
3. Names of substituent groups that complete the molecular structure

On determining the major chain, one should first know the different terms used for differently numbered carbon chains.

code no. of carbon

meth 1

eth 2

prop 3

but 4

pent 5

hex 6

One should also familiarize himself/herself with the codes used when there is the presence of double bonds or single bonds.

code means

an contains only carbon-carbon single bonds

en contains a carbon-carbon double bond

Alkyl Groups

Members of alkyl groups are produced when you remove a hydrogen atom from members of a family of compounds called alkanes. For example, CH4 is called methane but upon removing one of its H atom, CH3 or methyl is produced.

Here's a table of functional group priorities for nomenclature.

Aromaticity

Six carbons once formed in a ring,

with sp2 hybridization.

The strain was relieved,

and all six achieved

electron delocalization.

‘The stability, itself is dramatic,’

said a puzzled o-chemist fanatic.

‘All these factors at work

just add a new perk.’

And thus was proclaimed aromatic.