Chapter 4

Question 1

Hydrocarbons that lack pi bonds

Answer 1

saturated hydrocarbons or alkanes

Question 2

nomenclature

Answer 2

the system of rules for naming compounds

Question 3

What are the four steps of naming a compound?

Answer 3

1. identify the parent chain
2. name the substituents
3. number the carbon atoms of the parent and assign a locant to each substituent
4. assemble the substituents alphabetically, placing locants in front of each substituent. (for identical subst. use di, tri, tetra, penta, or hexa which are ignored when alphebetizing)

Question 4

Cycloalkanes

Answer 4

alkanes containing a ring

Question 5

Locant

Answer 5

number used to identify the location of a substituent

Question 6

Bicycloalkane

Answer 6

an alkane that has two rings that are connected to one another

Question 7

Differences when naming bicyclic compounds

Answer 7

1. the term “bicyclo” is used, and bracketed numbers indicate how the bridgeheads are connected
2. to number the parent, travel first along the longest path connected the bridgeheads

Question 8

Heat of Combustion

Answer 8

(in alkanes) the negative of the change in enthalpy (-△Hº) associated with the complete combustion of 1 mol of alkane in the presence of oxygen

Can be measured experimetnally and used to compare the stability of isomeric alkanes

Question 9

Cracking

Answer 9

a process by which C-C bonds of larger alkanes are broken, producing smalleralkanes suitable for gasoline.

Question 10

Reforming

Answer 10

a process in which straight chain alkanes are converted into branched hydrocarbons and aromatic compounds, which exhibit less knocking during combustion

Question 11

Rotation about C-C single bonds allows a compound to adopt a varitey of:

Answer 11

Conformations

Question 12

Newman projections

Answer 12

a drawing style that is designed to show the conformation of a molecule

Question 13

Dihedral angle

Answer 13

describes the relative postitions of one group on the back carbon and one group on the front carbon in a Newman projection

AKA torsional angle

Question 14

torsional strain

Answer 14

difference in energy between staggered and eclipsed conformations of ethane

Question 15

When does angle strain occur?

Answer 15

in cycloalkanes when bond angles are less than the preferred 109.5º

Question 16

Boat Conformation

Answer 16

a conformation of cyclohexane in which all bond angles are fairly close to 109.5º and many hydrogen atoms are eclipsing each other.

has significant torsional strain (eclipsing H’s & flagpole interactions)

can alleviate strain with twist boat