Double bonds, effect

For molecules with a double bond, effective lack of rotation about the double bond makes this type of isomer possible. 

The carbonium ion can now pick up electrons from the C5-C6 double bond, effecting ring closure and forming another, stable 3 carbonium ion at C5 ... 

Brown has shown that on introduction of a double bond to isomeric p-nitro-benzoates 52 and 53 the rate of solvolysis in either case decreases equally (about fivefold) which is due to the inductive double-bond effect and clearly points to the lacking anchimeric assistance in the solvolysis of206 this is also evidenced by the absence of tricyclic compounds among the reaction prcKiucts. Tlte isomers 206 and 207 are characterized by a high exotendo rate ratio and pr iominant formation of exo alcohol. 

In contrast to its parent substance, (weakly basic colorless diphenyl-amine), hexanitrodiphenylamine (I) is an acid which dissolves in sodium hydroxide or carbonate to produce orange-red solutions. This color change is due to a change in structure. Hydroxyl ions convert the baso-form of dipicrylamine (I) into the aci-form (II), in which a continuous chain of conjugated double bonds effects the deepening of color. ions convert the orange-red aci-form to the bright yellow water-insoluble baso-form ... 

No addition occurs any longer when the 3-butenyl chain is replaced by the homologous 3-pentenyl group.However, the nonterminal double bond effectively participates in an intramolecular S 2 -process (Scheme 1-104) that converts tributyl[(2-hexyl-5-methoxy-5-methyl-3-hexenyl)oxymethyl]stannane through the lithiated species into 2-hexyl-5-(2-methyl-l-propenyl)tetrahydrofiuan (143 87%, cis /trans 91 9). 

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