Cyclic Aliphatic Compounds

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Carbon atoms arranged in such a way as to form ring structures

Nomenclature

u Named by prefixing cyclo- to the corresponding open-chain hydrocarbon.

u Monocyclic aliphatic rings

u Polycyclic aliphatic rings

u Locate bridge-head carbons

u Determine the lowest number of rings

u mentally break bonds until no rings remain

u Indicate carbon number in the longest bridge, then the next longest bridge, etc., until all carbon atoms are utilized

u Began numbering at a bridge-head carbon of the longest bridge

Baeyer Strain Theory

u Adolf von Baeyer -- 1885

u Carbon to four other atoms with a bond angle of 109.5^o

u As the bond angle becomes more compressed, increasing strain is placed on the molecule

u As strain increases, bond stability decreases

Factors Affecting Stability

u Angle strain

u Torsional strain

u van der Waals strain (steric strain)

Preparation of Bicyclic compounds with 6 carbon ring

Preparation

u Two stage process

u Cyclization: conversion of an open-chain compound into a ring-containing compound

u Conversion: changing the cyclic compound into the wanted compound

Carbenes-cycloaddition

Addition of Substituted Carbenes