Chapter 6: Types of Organic Reactions and Intermediates

What is substitution mechanism?

It is ONE sigma bond BREAKING and ANOTHER bond forming at SAME carbon

What is elimination mechanism?

-It is TWO groups REMOVED, specifically two SIGMA bonds that are broken

-A PI bond is formed between ADJACENT atoms

What is addition mechanism?

Two groups are ADDED

When reaction mechanisms are involved, they are one or multiple steps. Nucleophiles and electrophiles are involved. What are they?

-Nucleophiles are LEWIS BASE

-Electrophiles are LEWIS ACIDS

What is a CONCERTED reaction?

-ONE step process

-Reactant converted DIRECTLY to product

-Does NOT matter amount of bonds broken/formed

What is a stepwise reaction?

-Multiple steps

-Reactant→ unstable reactive intermediate →product

-Intermediate CONSUMED during reaction

What are the three steps for radical halogenation?

Initiation, propagation, termination

What does initiation consist of?

Two radicals are formed via HOMOLYSIS of SIGMA bond

What does propagation consist of?

One radical reacts with a SECOND reactant to form NEW sigma bond and ANOTHER radical

What does termination consist of?

A stable molecule is formed from TWO radicals reacting together

What is homoyltic bond cleavage?

Electrons forming the bond between two atoms can be DIVIDED EQUALLY between two atoms of the bond to FORM RADICALS

What is heterolytic bond cleavage?

Two electrons that are forming a bond can be divided UNEQUALLY to form IONS

What are the different kinds of classes of radicals?

-Primary radical

-Secondary radical

-Tertiary radical (most stable since closest to achieving octet)

*The # indicates how many R groups are attached to the radical; 1 radical is always used

Are radicals electrophilic or nucleophilic?

Radicals are electrophilic

How do R groups stabilize electrophiles?

Via inductive effect; the electron density of the electrophilic carbon is INCREASED)

How can the stability of an intermediate be determined?

By using the octet rule

When carboanions are involved, are they classified as nucleophiles or electrophiles?

Nucleophiles

Which degree of radicals involving carboanions are most stable?

Methyl carboanion is most stable since carbon does not need any more electrons