Chemistry

Basics of Organic Chemistry

Basics of Organic Chemistry

Organic chemistry is a branch of Chemistry. Organic chemistry is the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds.

Tetravalency of Carbon

The atomic number of carbon is six. It consists of four electrons in the valence shell so it is called tetravalent. The four electrons are symmetrically distributed in space which forms four bonds arranged in a regular tetrahedron with a bond angle 109’28°.

Hybridization in Carbon Compound

sp^3

  • All bonds are single.
  • Tetrahedral symmetry.
  • 109’28° bond angle.
  • 25% s character.

sp^2

  • All bonds are double.
  • Trigonal planer symmetry.
  • 120° bond angle.
  • 33.3% s character.

sp

  • All bonds are single.
  • Linear geometry.
  • 180° bond angle.
  • 50% s character.

Effect of Hybridization on Bond Length and Bond Angle

C – C bond is formed by head-on overlapping (σ bond) having the largest bond length.

C ≡ C has two π bonds formed by sidewise overlapping, having smallest bond length.

Order Of Bond Length

C – C > C = C > C ≡ C

Or

sp^3  > sp^2 > sp

The shorter the length greater is the bond strength. So the order of bond strength so the order of bond strength is

C ≡ C > C=C > C-C

Or

sp > sp^2 > sp^3

Question: How many pie and sigma bonds are present in following?

  1. CH3CH = CH – CH3

π = 1

σ = 11

  1. CH3C ≡ N

π= 2

σ = 6

  1. CH3C ≡ C – CH = CH2

π = 3

σ = 10

Rules for IUPAC Naming

  • Selection of longest possible chain.

  • Lowest number rule.

  • Lowest sum rule.

  • Naming of complex chain.

  • Naming of side chain in alphabetical order.

Name of some structures:

1.

3,4 dimethyl hexane

2.

2,2 dimethyl butane

3.

3-ethyl 2,4,5 trimethyl heptane

Functional Group

Alcohol (-OH)

IUPAC – ol

  1. CH3 – OH

methanol

  1. CH3 – CH2 -OH

ethanol

CH2 – OH

  1. CH2 – OH

Ethane 1,2 – diol

Aldehyde (-CHO)

IUPAC – al

  1. HCHO

methanl (formaldehyde)

  1. CH3CHO

ethanal (acetaldehyde)

  1. CHO – CHO

Ethane 1,2 – diol

Ketone (-C=O)

IUPAC – one

  1. CH3 – C – CH3 = O

Propanone

  1. CH3 – C – CH3 = O

Butan – 2 – one

Carboxylic acid (-COOH)

IUPAC – oic acid

  1. HCOOH

methanoic acid

  1. CH3COOH

ethanoic acid

  1. COOH – COOH

ethane 1,2 – dioic acid

  1. HOOC – CH – CH – COOH

2,3 – dimethyl butane, 1,4 dioic acid

Esters

Symbol :

  1. CH3COOCH3

methyl ethanoate

  1. CH3COOC2H5

ethyl ethanoate

Acid Amide

Symbol:

  1. HONH2

methanamide

  1. CH3CONH2

ethanamide

Acid Halide

Symbol:

IUPAC – Alkanoyl halide

  1. CH3 – C – Cl double bond

2- ethanol chloride

  1. CH3 – CH2 – C – Br Double bond O

Propanoyl bromide

Amines (-NH2)

Primary Amines (-NH2)

IUPAC – Alkanamide

  1. CH3 – NH2

Ethanamide

  1. CH3 – CH – NH2

Methanamine

Secondary Amines

Symbol:

IUPAC – N- alkyl alkanamine

  1. CH3 – NH – CH3

N – methyl methanamine

Tertiary Amines

Symbol:

IUPAC – N,N dialkyl alkanamine

1.

N-ethyl-N-methyl-butanamide

Alkyl Cyanide

IUPAC – Alkal Nitride

  1. HCN

methane nitride

  1. CH3CN

ethane nitride

Seniority Table

IUPAC Naming of Alicyclic Compounds

1.

Cyclobutane

2.

Cyclopentanoic acid

3.

 

o

5-methyl cyclohex-2-en-1-one

4.

Cyclopentane Carboxylic acid

5.

Cyclohexane carbaldehyde

 

Isomerism

Two or more compounds which have the same molecular formula but different structural formula.

There are two types of isomers structural and stereoisomers.

Structural contains chain, position, functional, metamerism, and tautology.

Stereo-isomer includes geometrical and optical isomers

 

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