Organic Chemistry

Complex Substituents Ex. 1 IUPAC Name

Draw the structure and give the molecular formula for each of the following compounds. 1. t-butyl-cyclohexane 2. 1,1-dimethyl-3-(1,1,3-tri-methyl-butyl)-cyclooctane

Sharpes of alkanes sp 3 -Hybridization -Long-chain -Branched-chain C 4 H 10 Isomers

Isomers Same formula Different structure Different molecule with different properties – must have a different name! Isomers are different compounds with the same molecular formula.

Types of Isomers All Isomers Constitutional isomers (Structural isomers) Stereo isomers Cis-trans isomers (Geometric isomers) Other diastereomers (two or more chirality centers) DiastereomersEnantiomers

Constitutional isomers (Structural isomers) are isomers that differ in the order in which atoms are boned together. Isomers are different compounds with the same molecular formula. Constitutional isomers Structural isomers Positional Isomerism Skeletal Isomerism or Chain Isomerism Functional Isomerism

Skeletal Isomerism (Chain Isomerism) or Positional Isomerism Isomer of C 4 H 10

Isomer of C 4 H 8

Functional Isomerism

Isomer C 5 H 12

C 6 H 14

C 7 H 16

Molecular Formula Possible Number of constitutional Isomers Molecular Formula Possible Number of constitutional Isomers C 4 H 10 2 C 15 H 32 4,347 C 5 H 12 3 C 20 H ,319 C 6 H 14 5 C 30 H 62 4,111,846,763 C 7 H 16 9 C 40 H 82 62,481,801,147,341 C 8 H C 9 H C 10 H Number of alkane isomers

Stereoisomers -Geometrical Isomers (cis-trans isomers) -Optical Isomers Stereoisomers are isomers that differ only in the orientation of atoms in space.

Optical Isomers (s)-(+)- Cycloartenol Polarimetry

Types of Isomers All Isomers Constitutional isomers (Structural isomers) Stereo isomers Cis-trans isomers (Geometric isomers) Other diastereomers (two or more chirality centers) DiastereomersEnantiomers

Enantiomers are mirror-image isomers. R = RECTUS, UPRIGHT S = SINISTER, LEFT

Geometrical Isomers (cis-trans isomers)

Cis trans Cis Cis : Having similar group on the same side of a double bond or a ring. trans : Having similar group on opposite side of a double bond or a ring. Z : Having the higher-priority groups on the same side of a double bond or a ring. E : Having the higher-priority groups on opposite side of a double bond or a ring.

Physical Properties of Alkanes -Solubilities -Desities

Physical Properties of Alkanes

Boiling Points of Alkanes

-Surface area -Van der Waals attractions Intermolecular forces -Dipole-dipole -Van der Waals forces -Hydrogen bond

Boiling Points of Alkanes bp Structure

WHY ???

-Desities d  C

Sources

Reactions of Alkanes Combustion reaction CH 4 + O 2 C 5 H 12 + O 2

Substitution reaction -Halogenation reaction Heat or light

Mechanism of Halogenation reaction A radical mechanism 3 step -step 1 Chain Initiation -step 2 Chain Propagration -step 3 Chain Termination

step 1 Chain Initiation Chlororination of Methane Mech… step 2 Chain Propagration Mech…

step 3 Chain Termination

EX 1. CH 3 CH 2 CH 3 Cl 2 Light, 25 o C

Radicals (or free racdicals) are reactive intermediateds that have an unpaired electron. The relative stability of alkyl radical is as follows : High LOW