Chapter 3 Flashcards
classes of hydrocarbons
aliphatic: alkanes, alkenes, alkynes
aromatic: contains benzene rings
alkanes
hydrocarbons with only single bonds
CnH(2n+2)
alkenes
hydrocarbons with double bonds
CnH(2n)
alkynes
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)
benzene rings
not quite double bonds, or single, weak than double but stronger than single, thats why not alkene
isomers
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
unbranched alkanes names
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)
name branched isomers
(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
substitutien group
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
classification of groups
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
Boiling point surface area
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
Dipôle dipôle interractions
If another molecule is present (o, f, n, cl, Br) dipôle dipôle interaction present and boiling point higher
Hydrogen bonding and amine
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
Size halogen boiling point
Larger halogen, more polarized, so easier to induce bonds like in LDF and higher boiling point
Melting point and number of crabons
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
Dissolve
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
Solubility
Increases with shorter carbon chain and more polar CX bond where x is hallogen
Conformer
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
Hyperconjugations
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
Steric hyderance
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
branches IUPAC
List substituent in alphabetic order
dont aplhabetizes di, tri, etc
number them with the lower numbers in comparison to the other option
cycloalkane nomencalture
cyclo(number of carbon)
name alkyl substituent as usual
always number for smallest number
IUPAC alkyl halides
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
IUPAC alcohols
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
Angle strain
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
Torsional strain
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
Chair conformation
Cycholhexane completly free of strain
All angles are 111
All adjacent bond are staggered
Ring flip
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
boat conformation
2 close bonds both bringing down, (flagpole hydrogen)
Makes it unstable than chair conformation, steric strain
Half chair very unstable most
Most stable conformation
Biggest constituent in an equatorial plane
