Content OC Flashcards
electron domain: 4
geometry: linear
bond angle: 180
hybrid.: sp
electron domain: 3
geometry: trigonal planar
bond angle: 120
hybrid.: sp2
electron domain: 2
geometry: tetrahedral
bond angle: 109.5
hybrid.: sp3
single bond
one sigma
double bond
one sigma
one pi
triple bond
one sigma
two pi
determining greatest resonance contributer
the most stable will have a full octet on every atom
the most stable will have the smallest number of charges
the most stable will have neg. charges on the most electroneg. atoms and positive charge on the least electroneg. atoms
order of stability in newman projections
staggered > gauche > eclipsed axi
axial vs equatorial
equatorial bonds are more ________
stable ( lower energy ) than axial
place largest sub on equatorial to get greatest stability
cis
two subs. in the same direction
trans
two subs. in opposite direction
a lewis acid ______ electrons
accepts
a lewis base _______ electrons
donates
the stronger the acid, ______
the weaker/ more stable the conjugate base
the stronger the base, ________
the more stable/weaker the conjugate acid
pks for organic compounds
the more positively charged,
the more acidic
the more negatively charged,
the more basic
if all factors are about the same, then hydrogens acidity increases as the atom that it’s bonded to:
goes left to right across a row
goes down a column
electron withdrawing groups increase
acidity
electron donating groups decrease
acidity
s-orbitals tend to be more electroneg., so the more “s” character :
the stronger the acid
C
A
R
D
I
O
Charge: positively charged compounds are typically more acidic, negatively charged compounds are more basic
Atom: the more electroneg./ larger the atom with a negative charge, the more acidic the hydrogen is
Resonance: the more resonance stabilized the conjugate base, the stronger the acid
Dipole Induction: electron withdrawing groups increase acidity, electron donating groups decrease acidity
Orbitals: the more s-character an atom has, the more electroneg it is, and the more acidic hydrogens bonded to it will be sp3<sp2< sp
as KA increases, pka ____, and acid strength ______
decreases
increases
if the pH of the solution is lower than the pKa of the functional group,
the functional group will be protonated
if the pH of the solution is higher than the pKa of the functional group,
the functional group will be deprotonated
amino acid if protonated ( pH < pKa )
- NH3 +
amino acid if deprotonated ( pH > pKa )
-NH2
carboxylic acid group if protonated ( pH < pKa )
- COOH
carboxylic acid group if deprotonated ( pH > pKa )
- COO-
hydroxyl group if protonated ( pka > pH )
-OH
hydroxyl group if deprotonated ( pH > pKa)
-O-
when counting how many steroisomers one chiral molecule can have, use the equation:
2^n
n is the number of chiral centers
chiral molecules have the ability to
rotate olan polarized light when placed in a special machine called a polarimeter
Molecules that do not rotate plane-polarized light are called
achiral or inactive
there are 3 types of optically inactive ( or achiral ) molecules:
- 50/50 racemic mixture of two enantiomers ( racemic mixture )
- molecules that do not have stereochemistry in the them
- meso compounds
meso compound
any molecule with 2 or more chirality centers, and a line of symmetry
an enantiomer of a meso compound is exactly the same as the original molecule ( 2 are superimposable )
fisher projection
look up pls
a BIG point peak at 1700+/- 50 cm-1
C=O
a LARGE, broad trough far to the left for alcohols and on top of 3000 cm-1 for carboxylic acids
OH
big, pointy peaks coming straight down around 3000 cm-1
C-H’s
a sharp peak to the left of 3000 ( around 3200-3500)
N-H
(one peak for -NH, two peaks for -NH2)
medium sized peak at -2200
C (tripled bond) N
- a nitrile
vampire teeth at 1500-1600 and 1300-1400
NO2
carbon-carbon double bonds are found in which IR region?
1600 cm-1
carbon-nitrogen double bonds (imines) are found in which IR region?
1600 cm-1
UV-Vis spectroscopy
is used mostly to analyze compounds with conjugated double bonds
mass spectroscopy
technique used to determine a compounds mass
degree of unsaturation
(A-B) /2
a is the number of hydrogen atoms your compound would have if it didnt have any double bonds or rings
b is the number of hydrogen atoms your compound in question actually has
degree of unsaturation
c- (h/2) - (x/2)+ (n/2) +1
more negatively charged a carbon
further down to the right of 13C-NMR spectroscopy
more positively charged a carbon
further down to the left of 13C-NMR
Carbonyl carbons
- esters, amides, and carboxylic acids
- aldehydes and ketones
Kind of C-NMR?
160 - 180 ppm
> 200 ppm
TMS (tetramethysilane)
Kind of C-NMR?
0 ppm
not part of your compound?
1 H - NMR spectroscopy
carboxylic acid and amide H’s
12,13,14
1 H - NMR spectroscopy
phenols and aldehydes
10
1 H - NMR spectroscopy
aromatic land ( H’s stuck to benzene)
6,7,8
1 H - NMR spectroscopy
double bonds land
4,5,6
1 H - NMR spectroscopy
single bond land
1,2,3,4,5
1 H - NMR spectroscopy
Alcohol and amine H’s
0.5-5.5 ppm
1 H - NMR spectroscopy
TMS
0
not apart of your compound!
1 H - NMR spectroscopy
the more + charged =
more left, downfield
hydrogens get split by neighboring hydrogens. To figure out splitting,
count all the hydrogens next door in all directions and add (n+1 rule)
Intra-molecular Forces (within)
Covalent
two non metals atoms bond together and share electrons
Intra-molecular Forces (within)
Ionic bonds
metal bond to nonmetals and a transfer of electrons occurs
Intra-molecular Forces (within)
metallic bonds
metal atoms bond together and electrons flow freely around their nuclei
Inter- molecular Forces ( between molecules )
ion dipole
ionic compounds interacting with polar compounds
Inter- molecular Forces ( between molecules )
hydrogen bonding
H-O
H- N
H-F
Inter- molecular Forces ( between molecules )
dipole dipole
H-Cl
C-O
S-H
Inter- molecular Forces ( between molecules )
dispersion forces
hydrocarbons
single elements
non polar molecules
tollens test
reagent: Ag,O/NH3 or Ag(NH3)2
function group tested: aldehydes
positive result: sides of flask are coated with a silver mirror
iodoform test
reagent: I2/OH
functional group tested: methyl ketones
positive result: yellow percipitate forms (CHI3)
silver nitrate in alcohol
reagent: AgNO3 in alcohol
function group tested: alkyl halide s
positive result: precipitate of Ag compound formed
bromine test
reagent: Br2/CCl4
Functional group tested: alkenes and alkynes
positive result: brown color of bromine disappears
baeyer test
reagent: dilute KMnO4
functional groups tested: alkenes and alkynes
positive result: purple solution turns to brown precipitate
Jones Test
reagent: CrO3 / H2SO4
functional groups tested: 1 and 2 alcohols
positive result: orange reagent turns blue-green
Lucas Test
reagent: ZnCl2/HCl
Functional groups being tested: 2,3 and benzylic alcohols
positive results: cloudy solution initially, then separate layer forms
metallic
Interaction: Metallic Bonding
Properties: Variable hardness and melting point, conductive
Examples: Fe, Mg
Ionic
Interaction: Ionic
Properties: High melting point, brittle, hard
Examples: NaCl, MgO
Network
Interaction: Covalent Network
Properties: High melting point, hard, non conductive
Examples: C (diamond, graphite)
SiO2 (quartz)
Molecular
Interactions: H Bonding, dipole dipole, London dispersion
Properties: Low melting point, non conductive
Examples: H2, CO2
the stronger a molecules intermolecular forces:
higher the BP
higher its MP
lower its VP
melting points help determine a compounds
purity
for carboxylic acids, extract with
NaOH or NaHCO3
for phenols, extract with
NaOH
for amines, extract with
aqueous HCl
separates mixtures of 2 or more volatile liquids
distillation
used when 2 volatile liquids have boiling points that are closer together
fractional distillation
dissolves an impure compound in hot solvent and gradually precipitates the pure compound as the solution cools down
recrystallization
glass liquid chromatography
used to determine the relative abundance of each compound in a liquid mixture
separates components in liquid mixture by boiling point
lowest boiling point comes off the fastest
thin layer chromatography
separates compounds by their solubility in the solvent (polarity)
most soluble compound travels the fastest and furthest up the plate
usually uses polar plates and non polar solvent
compound that travels the furthest with non polar solvent is the most non polar compound
retention factor (Rf) is the number we use to tell how far up the TLC plate a compound travels
