Organic Chemistry Chapter 3

Front 1

What is a reaction mechanism

Back 1

a description of the events that take place on a molecular level as reactants become
products.

Front 2

Virtually all organic reactions fall into one of four categories:

Back 2

substitutions, additions,
eliminations, or rearrangements.

Front 3

In a reaction, when one group replaces another, this is known as?

Back 3

Substitution

Front 4

Substitutions are characteristic of what compounds?

Back 4

saturated compounds such as alkanes
and alkyl halides and of aromatic compounds (even though they are unsaturated)

Front 5

What happens in an Addition reaction?

Back 5

Additions are characteristic of compounds with multiple bonds. Ethene, for example,
reacts with bromine by an addition. In an addition all parts of the adding reagent appear
in the product; two molecules become one

Front 6

What happens in Eliminations?

Back 6

In an elimination one molecule loses the
elements of another small molecule. Elimination reactions give us a method for preparing
compounds with double and triple bonds.

Front 7

What do Reactions of organic compounds always involve?

Back 7

the making and breaking of covalent bonds.

Front 8

A covalent bond may break in two fundamentally different ways. What are they?

Back 8

When a bond breaks such that one fragment takes away both electrons of the bond,
leaving the other fragment with an empty orbital, this kind of cleavage is called
heterolysis

When a bond breaks so that each fragment takes away one of the electrons of the
bond, this process is called homolysis

Front 9

What happens in homolytic bond cleavage?

Back 9

Each fragment keeps one electron leading to Radicals.

Front 10

In Heterolytic bond cleavage, what type of fragments result?

Back 10

Ions are produced from polarized compounds. Assistance is needed to produce this reaction since polar bonded compounds attract each other, a solvent with a lone pair of electrons is needed.

Front 11

What is a Brønsted–Lowry acid–base reactions

Back 11

involve the transfer of protons.

Front 12

A Brønsted–Lowry acid is

Back 12

is a substance that can donate (or lose) a proton.

Front 13

A Brønsted–Lowry base

Back 13

is a substance that can accept (or remove) a proton.

Front 14

The molecule or ion that forms when an acid loses its proton is called the

Back 14

conjugate base

Front 15

The molecule or ion that forms when a base accepts a proton is called the

Back 15

conjugate acid

Front 16

In the Lewis acid–base
theory:

Back 16

Acids are electron pair acceptors.

Bases are electron pair donors.

Front 17

In Lewis acid–base theory, who are the proton donors?

Back 17

proton donors are not the only acids; many other species are
acids as well. Aluminum chloride, for example, reacts with ammonia in the same way that
a proton donor does.

Front 18

Because carbocations are electron-seeking reagents chemists call them

Back 18

electrophiles
(meaning electron-loving).

Front 19

Electrophiles are

Back 19

reagents that seek electrons so as to achieve a stable shell of
electrons like that of a noble gas.

All Lewis acids are electrophiles. By accepting an electron pair from a Lewis
base, a carbocation fills its valence shell.

Front 20

Carbanions

Back 20

are Lewis bases

Front 21

What is a carbanion considered to be?

Back 21

A nucleophile is a Lewis base that seeks a positive center such as a positively
charged carbon atom.

Front 22

How to Use Curved Arrows in Illustrating Reactions

Back 22

-show the direction of electron flow in a reaction mechanism.

-point from the source of an electron pair to the atom receiving the pair. (Curved
arrows can also show the movement of single electrons. We shall discuss reactions
of this type in a later chapter.)

- always show the flow of electrons from a site of higher electron density to a site of
lower electron density.

-never show the movement of atoms. Atoms are assumed to follow the flow of the
electrons.

Front 23

acid strength is characterized in terms of

Back 23

of acidity constant (Ka)
or pKa values.

Front 24

Inductive effects are

Back 24

Inductive effects are electronic effects transmitted through bonds. The inductive
effect of a group can be electron donating or electron withdrawing. Inductive
effects weaken as the distance from the group increases.

Front 25

What is energy?

Back 25

Energy is
defined as the capacity to do work

Front 26

What are the two types of energy?

Back 26

and potential energy.
Kinetic energy is the energy an object has because of its motion; it equals one-half the
object’s mass multiplied by the square of its velocity (i.e., ).
Potential energy is stored energy. It exists only when an attractive or repulsive force
exists between objects.

Front 27

Chemical energy is a form of?

Back 27

Potential Energy

Front 28

What is a protic solvent?

Back 28

is one that has a hydrogen atom attached to a strongly electronegative
element such as oxygen or nitrogen.

Front 29

The conjugate acid of an alcohol is often called a

Back 29

a protonated alcohol, although more
formally it is called an alkyloxonium ion or simply an oxonium ion.

Front 30

An atom with an unshared electron pair is not the only locus that confers basicity on an
organic compound. What else can function as a base?

Back 30

The p bond of an alkene can have the same effect. Later we shall study
many reactions in which, as a first step, alkenes react with a strong acid by accepting a
proton