Structure and reactivity of organic molecules Flashcards
heteroatoms
non metals on the periodic table which will be delta negative when bonded to carbon or hydrogen.
heteroatoms symbol
A
metals
atoms on the left side of the periodic table, including boron and silicon which will be delta positive when bonded to carbon or hydrogen.
metal symbols
M
order of electronegativity
M < H < C < A
explanation of carbon hydrogen bond polarity
carbons electronegativity is 2.6 and hydrogens is 2.2 so the difference in electronegativity is not enough to make a polar covalent bond.
delta negative atom in polar covalent bond
the atom which will have a greater pull on the bonding electrons and therefore is the nucleophile
delta positive atom in polar covalent bond
the atom which has a weaker pull on the bonding electrons and therefore is the electrophile.
what affects an atoms reactivity
dipoles from polar covalent bonds
hydritic definition
where a hydrogen will have a greater pull on the bonding electrons
protic definition
where a hydrogen will have a weaker pull on the bonding electrons.
LUMO characteristics
the LUMO is an electrophile, meaning it will accept electron pairs from electron rich sites such as nucleophiles.
HOMO characteristics
the HOMO is a nucleophile, meaning it will donate electron pairs to electron deficient sites such as an electrophile.
electron pairs on organic atoms
carbon has 4 bonding pairs
nitrogen has 3 bonding and 1 non bonding
oxygen has 2 bonding and 2 non bonding
halogens will have 1 bonding and 3 non bonding electron pairs
extra bond rule for organic atoms
an extra bond means a lone pair has formed a dative bond, resulting in a lone pair forming a bonding pair, giving the atom an extra positive charge.
fewer bonds rule
if there are fewer bonds on an atom than normal it means that the atom has formed an extra lone pair, which will result in an extra negative charge.
when can an atom form extra bonds
when the atom has a lone pair which it can use to form a dative covalent bond
cationic species properties
their positive charge will mean the ion will accept electron pairs more easily, making it a stronger Lewis acid and electrophile.
anionic species properties
their negative charge will mean that they will donate electron pairs more easily, meaning they will be a stronger Lewis base and nucleophile.
Lewis acid
An electron pair acceptor, and therefore an electrophile
Lewis base
An electron pair donator, and therefore a nucleophile
Bronsted base definition
An electron rich proton acceptor.
Bronsted acid definition
An electron deficient proton donator.
important orbital type in Bronsted acids
Lumo
important orbital type in Bronsted bases
Homo
reason that carbon has stronger bonds than silicon
carbon’s 2p orbitals will be smaller than silicon’s 3p orbitals, which will result in a larger relative area of overlap in carbons molecular orbitals than silicon’s molecular orbitals, resulting in shorter stronger bonds for carbon compounds allowing for carbon to form larger more complex molecules.
alcohol classifications
primary alcohols will have 1 carbon to carbon bond adjacent to the alcohol group.
secondary alcohols will have 2 carbon to carbon bonds adjacent to the alcohol group
tertiary alcohols will have 3 carbon carbon bonds adjacent to the alcohol.
amine classifications
primary means 1 N - C bond
secondary means 2 N - C bonds
tertiary means 3 N - C bonds.
quaternary means 4 N - C bonds
functional groups note
typically consisting of heteroatoms or carbon double/ triple bonds because they have pi electrons.
saturated molecule definition
where a molecule contains only sigma bonds
unsaturated definition
where a molecules contains a double or triple bond meaning it contains pi bonds.
unsaturated molecule types
Aryls
Alkene
Alkyne
alkyne functional group
c triple bond c
Aryl functional group
benzene ring attached to something
alkene functional group
c=c
alcohol functional group
OH
ether functional group
R - O - R
Amine functional group
N
Nitro compound functional group
N+=O
O-
aldehyde functional group
C = O
H
ketone functional group
C = O
R
carboxylic acid functional group
C = O
OH
ester functional group
C=O
O
C
acyl chloride functional group
C = O
Cl
Amide functional group
C =O
N
Acetal functional group
R - O - C - O - R
nitrile functional group
C triple bond N
acid anhydride functional group
C=O
O
C=O
oxidation classification
0 C - X
1 C - X
2 C - X
3 C - X
4 C - X
0 C - X
alkanes
1 C - X
molecules with 1 heteroatom bond + alkenes
2 C - X
molecules with 2 heteroatom bonds + alkynes
3 C - X
molecules with 3 heteroatom bonds
4 C - X
molecules with 4 heteroatom bonds
rules for oxidation classifications
look only at the atom with the highest number of C - X bonds to determine oxidation classification.
reduction definition
where there is a gain of electrons or hydrogen
where there is a loss of oxygen
oxidation definition
where there is a loss of electrons or hydrogen
where there is a gain oxygen
reason for alkenes being part of alcohol oxidation classification
one of the carbons in the unsaturated double bond will gain hydrogen, meaning it is reduced, whereas the other carbon in the unsaturated carbon to carbon double bond will gain a heteroatom, meaning it will be oxidized.
this will result in redox neutral reaction/ transformation.
reason that alkynes are part of the aldehydes classification
One of the carbons in the unsaturated carbon to carbon triple bond will gain 2 hydrogens meaning it will be reduced twice, whereas the other carbon will gain a double bond with an oxygen meaning it is oxidized twice.
this will result in a redox neutral transformation between any 2 C - X molecule and an alkyne.