3. Organic Compounds: Alkanes and Their Stereochemistry

Question 1

collection of atoms at a site that have a characteristic
behavior in all molecules
where it occurs

Answer 1

Functional group

Question 2

have special
bonds that are
represented as
alternating single
and double C-C
bonds in a six-membered ring

Answer 2

Arenes

Question 3

Functional Groups with Carbon Singly
Bonded to an Electronegative Atom

Answer 3

• Alcohol
• Alkyl halide
• ether
• phosphate

Question 4

Groups with a Carbon–Oxygen Double Bond
(Carbonyl Groups)

Answer 4

• aldehyde
• ketone
• carboxylic acid
• ester
• thioester
• amide
• acid chloride

Question 5

Compounds with C-C single bonds and C-H
bonds only (no functional groups)

saturated with hydrogen (no more can be added

also called aliphatic compounds

Answer 5

Alkanes

Question 6

Alkanes with C’s connected to no more than 2 other
C’s

Answer 6

straight-chain or normal alkanes

Question 7

Alkanes with one or more C’s connected to 3 or 4 C’s

Answer 7

branched-chain alkanes

Question 8

Isomers that differ in how their atoms are arranged in
chains

They must have the same molecular formula to be
isomers

Answer 8

constitutional isomers

Question 9

does not show bonds but lists atoms

Answer 9

condensed structure

Question 10

11 - undecane
12 - dodecane
13 - tridecane
14 - tetradecane
20 - icosane
30 - triacontaine

Question 11

remove one H from an alkane (a
part of a structure)

Answer 11

Alkyl group

Question 12

a carbon at the end of a chain (primary alkyl group)

a carbon in the middle of a chain (secondary alkyl
group)

a carbon with three carbons attached to it (tertiary alkyl
group)

Question 13

If two different chains of equal length are
present, choose the one with the larger
number of branch points as the parent

Question 14

If there is branching an equal distance away from both ends of the parent chain, begin numbering that the end nearer the second
branch point

Question 15

If there are two substituents on the same carbon, give them both the same number

Question 16

(low affinity compounds)
because they do not react as most chemicals

Answer 16

Paraffins

Question 17

Boiling points and melting points increase as size of
alkane increases

Question 18

Different arrangement of
atoms resulting from bond rotation

Answer 18

Conformation

Question 19

Conformations can be represented in 2 ways:

Answer 19

• sawhorse representation
• newman projection

Question 20

most stable: all 6 C-H bonds are as far away as possible

low potential energy

Answer 20

Staggered

Question 21

least stable: all 6 C-H bonds are as close as possible to each other

high potential energy

Answer 21

Eclipsed

Question 22

Conformational situation is more complex for larger alkanes

Question 23

Not all staggered conformations has same energy, and not all eclipsed conformations have same energy

Question 24

methyl groups are 180˚ apart

Answer 24

Anti conformation

Question 25

methyl groups are 60˚ apart

Answer 25

Gauche conformation

Question 26

repulsive interaction occurring between atoms that are forced closer together than their atomic radii allow

Answer 26

Steric strain

Question 27

H-H Eclipsed - torsional strain

Answer 27

4.0

Question 28

H-CH3 Eclipsed - mostly torsional strain

Answer 28

6.0

Question 29

CH3-CH3 Eclipsed - torsional and steric strain

Answer 29

11

Question 30

CH3-CH3 gauche - steric strain

Answer 30

3.8

Question 31

arises when atoms get close to each other and the electron clouds repel each other

staggered or eclipsed

Answer 31

Steric strain

Question 32

electrons and the bonds that repel each other whenever you have an eclipsed conformation

Answer 32

Torsional strain

Question 33

two bulky groups that are 60 degrees apart; steric strain

Answer 33

Gauche

Question 34

why does the H-H eclipsed have a higher potential energy compared to CH3-CH3 gauche interaction?

Answer 34

Because H-H eclipsed are much closer even though the atoms are smaller