Chapter 8

Question 1

chlorofluorocarbons (CFCs)

Answer 1

used as refrigerants, aerosols, plastics, dry cleaning

-largely responsible for destroying ozone layer

Question 2

haloalkane (alkyl halide)

Answer 2

a compound containing a halogen atom covalently bonded to an sp3-hybridized carbon; gives the symbol RX

Question 3

Haloalkane (vinyl halide)

Answer 3

a compound containing a halogen atom bonded to an sp2 hybridized carbon

Question 4

haloarene (aryl halide)

Answer 4

a compound containing a halogen atom bonded to a benzene ring; given the symbol ArX

Question 5

IUPAC

Answer 5

1. number parent chain to give substituent encountered first the lowest number, whether it is a halogen or an alkyl group
2. indicate halogen substituents by the prefixes fluoro-, chloral-, bromo-, and iodo- and list them in alphabetical order w other substituents
3. locate each halogen on the parent chain by giving it a number preceding the name of the halogen
4. in haloalkanes, number the parent chain to give carbon atoms of the double bond the lower set of numbers

Question 6

haloform

Answer 6

a compound of the type CHX3 where X is the halogen

Question 7

perhaloalkane

Answer 7

hydrocarbon with all hydrogen’s replaced by halogens

Question 8

physical properties of haloalkanes

Answer 8

A. Polarity
-halogen leads to polarization of bond with partial neg on halogen and partial pos on carbon
-dipole moment = q x d (q=sum of charges, d = bond length)
B. Boiling point
-higher for haloalkane vs alkane of comparable size due to polarizability
C. Density
-all liquid haloalkanes are more dense than those of hydrocarbons of comparable weight
D. Bond lengths and strengths
-C-F bonds are stronger than C-H bonds, C-Cl, C-Br, and C-I bonds are weaker

Question 9

van der Waals forces

Answer 9

a group of intermolecular attractive forces including dipole-dipole, dipole induced dipole, and induced dipole-induced dipole forces
-for constitutional isomers, more branches = more compact shape, decreased van der Waals and lower boiling points

Question 10

van der Waals radius

Answer 10

minimum distance to an atom that does not cause non bonded interaction strain

Question 11

polarizability

Answer 11

a measure of the ease of distortion of the distribution of e- density about an atom or group in response to interactions with other molecules and ions

Question 12

heterocyclic bond cleavage

Answer 12

cleavage of a bond so that one fragment retains both electrons and the other retains none

Question 13

radical

Answer 13

any chemical species containing one or more unpaired electrons

Question 14

hemolytic bond cleavage

Answer 14

cleavage of a bond so that each fragment retains one electron; formation of radicals

Question 15

substitution

Answer 15

a reaction in which an atom or group of atoms in a compound is replaced by another atom or group of atoms

Question 16

regioselectivity

Answer 16

radical substitution to form haloalkanes faves the more substituted product

Question 17

radical chain mechanism

Answer 17

1. initiation: radical forms
2. propagation: radicals react and form new radicals
3. termination: radicals react and go away

Question 18

Hammond’s postulate

Answer 18

the structure of the transition state for an exothermic step looks more like the reactants of that step, while the structure of the transition state for an endothermic step looks more like the products of that step

Question 19

allylic carbon

Answer 19

a carbon next to a carbon-carbon double bond

Question 20

allylic substitution

Answer 20

any reaction in which an atom or group of atoms is substituted for another atom or group of atoms at an allylic carbon
-useful reagent: N-bromosuccinimide (NBS)

Question 21

order for allylic halogenations

Answer 21

1. make the most stable radical
2. resonance
3. make the most stable double bond

Question 22

autooxidation

Answer 22

air oxidation of materials such as unsaturated compounds