Organic Chem Flashcards
organic chem
chemistry of carbon and carbon compounds (H, O, N)
hydrocarbons
simplest organic molecule made of only C and H
- many forms come from crude oil
saturated
hybridised sp3 carbons from 4 sigma bonds
unsaturated
sp or sp2 carbons can form double or triple bonds
unsaturated hydrocarbons
alkenes, alkynes, arenes
saturated hydrocarbons
alkanes
alkenes
double bond, 2 sp2 carbons (1 pi and 1 sigma)
- 120 degrees between groups
alkynes
triple bond, 2 sp carbons (linear)
arenes
one or more benzene rings
saturated
only single CC bonds
C-C
sigma bond
alcohol
OH
ether
O-R
amine
NH2
alkyl halide
X = F, Cl etc.
aldehyde
COH
ketone
COR
carboxylic acid
COOH
ester
COO
amide
ONHR
naming alkanes
meth - ane
number of carbons, its an alkane
properties of alkanes
melting points, boiling points and density increase with increasing length of chain - intermolecular forces !
naming cyclic structures
cyclopro- cyclic, number of carbons
isomers
having identical molecular formula but different structure
- cannot convert into another without breaking bonds
constitutional isomers
have different order of attachment of atoms
conformers
not isomers, bonds are rotated into different structures
naming constitutional isomers
- identify longest chain
- count so that the branch has the lowest number
- name the branches
2,2 dimetylbutane
alkene formula
CnH2n
alkyne formula
CnH2n-2
alkene isomers
diastereoisomers- same connectivity but different positions of groups in space
naming diastereoisomers
- assign priority based on atomic number (C=o counts as two Os).
- determine if high priority are on the same side
yes: Z
no: E
naming alkenes
E or Z in front, 4-methylpent-2- ene (methyl has lower priority than double bond)
naming cycloalkenes
3-chloropentene
start counting at double bond, lowest number for Cl (or whatever sticks off)
conformations of organic molecules
rotations, requires little energy (not like breaking bonds)
can be eclipsed (line up) or staggered
more repulsion if eclipsed, staggered is more stable
drawing cyclohexane
axial (up/down), equatorial (sideways) - favoured as they do not repel as much
axial are close and dumb into each other - sterically repel
might conform from chair to boat where all axial become equatorial
synthesis
addition, substitution, oxidation and reduction
addition
adding atoms to a molecule
substitution
exchanging an atom/group from a molecule
oxidation
loss of electrons (or H)
reduction
gain of electrons (or H)
addition with alkenes and strong acids
strong acids give up a proton. alkene becomes a halogenated alkane
nucleophilic alkene is more electron rich than an alkane
HCL (H+ is electrophilic)
- H binds and double bond breaks. carbonation occurs (vacant orbital), other end is positive
- the Cl- is a nucleophile and binds with positive end
this product is more stable and has least energy
markovnikov’s rule
when both ends of an alkene have different numbers of hydrocarbons (not symmetrical), two products can be formed - major (more stable) and minor.
addition of H-X to an alkene occurs such that the carbon with more gains most.
nucleophile
an atom with a lone pair of electrons or a pi bond
electrophile
an atom with a vacant orbital or polarised bond
dihalogenation reaction
alkene reacts with X-X
the double bond breaks and one X binds, causing carbonation.
X- binds with positive end and you get an alkane with two Xs
hydration reaction
an alkene reacts with water and sulphuric acid (a catalyst)
the H from the acid breaks the bond and causes a positive end. then the water binds.
why does oxygen add to the secondary carbon rather than the primary in a hydration reaction?
Markovnikov’s rule - increased stability, adding water to the carbon with more carbon substituents, than at the end where the H was initially added
a methyl cation CH3+ is unstable, a tertiary cation CC4 is stable
hyper conjugation: stabilising interaction from mixing a filled sigma orbital with an adjacent empty orbital
