Chapter 3

Question 1

classes of hydrocarbons

Answer 1

aliphatic: alkanes, alkenes, alkynes
aromatic: contains benzene rings

Question 2

alkanes

Answer 2

hydrocarbons with only single bonds

CnH(2n+2)

Question 3

alkenes

Answer 3

hydrocarbons with double bonds

CnH(2n)

Question 4

alkynes

Answer 4

hydrocarbons with triple bonds
(can also be alkene at the same time if double and triple bonds are present, it is both alkene and alkyne)

CnH(2n-2)

Question 5

benzene rings

Answer 5

not quite double bonds, or single, weak than double but stronger than single, thats why not alkene

Question 6

isomers

Answer 6

same molecular formula, but different

constitutional: atoms connected differently
stereo: connected the same way, but arranged in space differently

number of isomers increases with carbons

Question 7

unbranched alkanes names

Answer 7

1 C: mehtane
2: ethane
3: propane
4: butane
5: pentane
6: hexane
7: heptane
8: octane
9: nonane
10: decane
11: undecane
12:dodecane
13:tridecane
14:tetradecane
15:pentadecane
16:hexadecane
17: heptadecane
18:octadecane
19:nonadecane
20:icosane
25:pentacosane
30:triacontane

-ane from alkane (single bond)

n-hexane or hexane is named of unbranched (no substitutent) of hexane (straight chain)

Question 8

name branched isomers

Answer 8

(lowest number of carbon where branch is attached)-(name of group of substituent)(name of longuest chain)

ex:

2-methylpentane
2,3-dimethylbutane
2,2-dimethylbutane

Question 9

substitutien group

Answer 9

change suffix with -yl (ex methyl)

otherwise

find carbon of connection to rest of atom and number it 1, find longuest chain and number it

(shortest chain attached to what number of carbon)-(shortest group name)(longest group name)

ex:

1-methylethyl

Question 10

classification of groups

Answer 10

primary (point of atatchement carbon attached to one other carbon in the substitutient group)
secondary (attached to 2 carbon)
tertiary (attached to 3 carbon)

Primary, secondary, tertiary depending on the number of carbons bonded to the carbon attached to the hydroxyl/halide/site of attachement attached

Question 11

Boiling point surface area

Answer 11

More carbon, more surface area, more non polar, more London dispersion forces, higher boiling point

The more branches/ alkyl substituent in an isomer, the lower the boiling point

Solubi

Question 12

Dipôle dipôle interractions

Answer 12

If another molecule is present (o, f, n, cl, Br) dipôle dipôle interaction present and boiling point higher

Question 13

Hydrogen bonding and amine

Answer 13

If OH present, hydrogen bonding present and boiling point increased (even more than dipôle dipôle)

Same with Amine (nh2) but less that hydroxyl group because electro negativity not that different

Hydrogen bonds are stronger in primary amines than in secondary because primary amines have a stronger dipôle dipôle interaction

Tertiary Amine scannot form hydrogen bonds togetheri

Question 14

Size halogen boiling point

Answer 14

Larger halogen, more polarized, so easier to induce bonds like in LDF and higher boiling point

Question 15

Melting point and number of crabons

Answer 15

Even number of carbons are packed a little bit more tightly together and the intermolecular forces are a little stronger, so melting point slightly higher

Question 16

Dissolve

Answer 16

Like dissolves like because interaction are stronger when similar

To dissolves, a molecule of solute has to be surrounded by molecules of solvent, so solvent has to have strong bonds with solute to disconnect it from similar solutes

Important in drug action, because cell membrane non polar, so all drugs have to have a portion that is non polar to dissolve in cell membrane

Question 17

Solubility

Answer 17

Increases with shorter carbon chain and more polar CX bond where x is hallogen

Question 18

Conformer

Answer 18

When atoms spin around a single bond, infinite amount of conformées

Newman projections

Staggered: get groups in the back as far from front groups, more stable because electrons are as far away as possible. Also most stable because of hyperconjugation
Eclipsed : everything lines up perfectly, less stable because electrons closer to each other, more potential energy

Staggered can be gauche: alkyl groups next to each other
Or anti: alkyl groups are opposite (one up one down) because of more far than each other, anti is more stable than gauche because electrons clouds repel each other and now they have more space

Question 19

Hyperconjugations

Answer 19

When Staggered, 2 orbitals with sp3 hybridized orbital
Electrons from sigma bonding orbitals and move into anti bonding orbital of other carbon, will be more stable

Question 20

Steric hyderance

Answer 20

Alkyl group have a much higher tendance to be staggered because of the carbon, it’s size and it’s electro negativity compared to hydrogen

Steric hyderance is the repulsion between 2 atoms ELECTRON CLOUD

Question 21

branches IUPAC

Answer 21

List substituent in alphabetic order
dont aplhabetizes di, tri, etc
number them with the lower numbers in comparison to the other option

Question 22

cycloalkane nomencalture

Answer 22

cyclo(number of carbon)
name alkyl substituent as usual
always number for smallest number

Question 23

IUPAC alkyl halides

Answer 23

functional class nomenclature

name alkyl group and the halogen as seprate words
ex: 1-ethylmethyl bromide
cychohexyl iodide

substitutive nomenclature
name halo-subsituted alkanes
number longuest chain containing halogen and give it the lowest number
ex: 5-chloro-2-methylheptane

halogens and alkyl groups are equally as important when it comes to numbering the chain

Question 24

IUPAC alcohols

Answer 24

functional class nomenclature

add alcohol as seperate word
ex: 1.1-dimethylbutyl alcohol

substitutive nomenclature

name as alkanols,
replace e ending of alkane wih ol
ex: 2-methyl-pentan-2-ol

alcohol has priority when it comes to numbering the gorups, give it lowest number always

Question 25

Angle strain

Answer 25

Angle of carbon (sp3) wants to be at 109.5 but is strained to be 60* for example when in cyclopropane, so angle strain

Not in 120 degree because cyclohexane not planar molecule, so angle isn’t really 120*

Poor overlap of bonds, weak bond when bond angle less than ideal bond angle

Once in cyclobutane, molecule can now twist to release angle strain and be less eclipse,
As carbons increase, more twisting available and becomes much more staggered and stable

Question 26

Torsional strain

Answer 26

resistance to twisting in molecules

Type of strain that forces molecules to twist in a certain way, to reduce torsional strain

As we get to cyclohexane, less torsional strain

Question 27

Chair conformation

Answer 27

Cycholhexane completly free of strain

All angles are 111

All adjacent bond are staggered

Question 28

Ring flip

Answer 28

Equatorial bonds become axial and axial bonds become equatorial.

Changes orientation of everything around it

If for example methyl group is axial, is has 1,3-diaxial strain with 1-hydrogen and 3-hydrogen, so ring flip makes it equatorial and more stable

Question 29

boat conformation

Answer 29

2 close bonds both bringing down, (flagpole hydrogen)

Makes it unstable than chair conformation, steric strain

Half chair very unstable most

Question 30

Most stable conformation

Answer 30

Biggest constituent in an equatorial plane