Aliphatic cyclic compounds Islamic University of Gaza

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Presentation transcript:

Aliphatic cyclic compounds Islamic University of Gaza Organic chemistry B Chapter 13 Aliphatic cyclic compounds Alicyclic compounds By Prof. Dr. Adel M. Awadallah Islamic University of Gaza

Cycloalkanes: Nomenclature

Industrial source

Preparation

Reactions similar to that of alkanes (free radical substitution) ,

Reactions alkenes (addition or cleavage of the double bond)

Ring Strain in Cyclopropane Average heat of composition per CH2 = 157.4 Kcal / mol Ring strain in cyclopropane = 27.6 Kcal/mol Ring strain in cyclobutane = 26.3 Kcal/mol

Ring Strain in Cyclopropane Eclipsing (torsional) strain: Strain resulting from deviation from the staggered arrangement Bond-Angle Strain: Strain resulting from deviation from the normal bond angle (tetrahedral 109.5)

Addition to cyclopropane

Addition to cyclopropane Cyclobutane undergoes hydrogenation under vigorous conditions

Relieve of torsional strain in cyclobutane Puckered structure (butterfly)

Relieve of torsional strain in cyclopentane Envelope (half chair) structure

Conformations of Cyclohexane

Conformations of cyclohexane

Twist boat is more stable than the boat conformation

1,2 + 1,4 Trans diaxial or diequatorial 1,3 cis diaxial or diequatorial

Example