Organic Chemistry Flashcards
Isomers
same molecular formula but different structural arrangements
Structural Isomers
same molecular formula, different connectivity
Stereoisomers
Same molecular formula, same connectivity
Conformational Isomers
Type of stereoisomer, does not require bond breaking to interconvert (differs in rotation around single sigma bond)
-antistaggered, gauche, éclipsed, total eclipsed conformations
Configurational Isomers
Type of stereoisomer, does require bond breaking to interconvert
Form either diastereomers or enantiomers
Diastereomer
Type of configurational Isomer, superimposable mirror images
two chiral molecules, share same connectivity, NOT mirror images of each other
Enantiomer
type of configurational isomer, nonsuperimposable mirror images
Same connectivity, but opposite configurations at every chiral center
Same physical and chemical properties
DIFFERENT optical activity and reaction in chiral environments
Optical activity
rotation of plane polarized light around a chiral molecule
Direction can only be determined experimentally
Chirality
handedness, if the mirror image CANNOT be superimposed – meaning that the molecule DOES NOT have an internal plane of symmetry
Racemic mixture
when both + and - enantiomers are present in equal proportions
Cis-Trans Isomers
geometric isomers, type of diastereomer
substituents differ in position around an immovable bond
MESO compounds
internal mirror plane, Newman projections are the same
“chiral centers that HAS an internal plane of symmetry
E and Z configurations
describe absolute configuration around double bonds
R and S
describes chiral centers (stereo centers)
S: counter clockwise
R: Clockwise
sp3 hybridization
tetrahedral geometry
109.5 bond angle
carbons w/ all single bonds
sp2 hybridization
trigonal planar geometry
120 bond angle
carbons w/ one double bond
sp hybridization
linear geometry
180 bond angle
carbon w/ triple or 2 double bonds
acidic functional groups
alcohols
aldehydes
ketones
carboxylic acids
basic functional groups
amines
amides
SN1 Reaction
unimolecular nucleophilic substitution reaction
1. leaving group leaves forming carbocation, 2. Nu attacks planar carbocation = racemic mixture
-prefers highly sub carbons
-rate ONLY dependent on substrate
rate = k[substrate]
SN2 Reaction
bimolecular nucleophilic substitution reaction
1. Nu attacks @ same time leaving group leaves
Nu backside attack = inversion in stereochemistry
- rate dependent on substrate and Nu
rate = k[Nu][substrate]
phenols
benzene rings w/ hydroxyl groups ortho- adjacent carbons meta- separated by one carbon para- opposite sides of the ring *are more acidic due to their delocalized charge of conjugate base
oxidation of primary-OH by PCC
aldehyde
oxidation of primary-OH by strong oxidizing agent
carboxylic acid
oxidation of secondary-OH
ketone
Tautomers
isomers, interconnected by moving a H and double bond ex: keto and enol forms
physical properties of Carboxylic Acids
Polar, H bond very well
Increases boiling point
often dimers in solution
acidity is enhanced by resonance + e- that are donating
COOH + Nu (ammonia or amine) =
amide forms
COOH + Nu (alcohol) =
ester forms
COOH + Nu (COOH) =
anhydride forms
Saponification
long chain COOH (fatty acid) + strong base = salt (or soap)
condensation reaction of COOH and OHs
ester
suffix -oate
Nonpolar Nonaromatic Amino Acids (7)
Alanine Valine Leucine Isoleucine Glycine Proline Methionine
Aromatic Amino Acids (3)
tryptophan
Phenylalanine
Tyrosine
Polar Amino Acids (5)
Serine Threonine Asparagine Glutamine Cysteine
Negatively Charged Amino Acids (2)
Aspartic Acid
Glutamic Acid
Positively Charged Amino Acids (3)
(amines in their R groups)
Arginine
Lysine
Histidine
Nonpolar nonromantic and aromatic amino acids both-
tend to be hydrophobic, reside in the interior
Polar, negatively and positively charged amino acids both-
hydrophilic, reside on surface of proteins
Strecker Synthesis
generates amino acids from an aldehyde
aldehyde + NH4Cl + KCN
Gabriel Syntesis
generates amino acids from potassium phthalimide, diethyl bromomalonate, alkyl halide
Infrared Spectroscopy
to appear, bond vibration changes bond dipole moment
IR Spectroscopy: O-H peak
broad, around 3300 cm-1
(alcohols, water, COOH)
COOH may shift around 3000 cm-1
IR Spectroscopy: N-H peak
sharp, around 3300 cm-1 (amines, imines, amides)
IR Spectroscopy: C=O peak
sharp, around 1750 cm-1
aldehydes, ketones, COOH, amides, esters, anhydrides
Nuclear Magnetic Resonance (NMR)
- measures alignment of nuclear spin
- determines connectivity of compound and functional groups
- pulses push nuclei from lower energy (alpha) state to higher (beta) state
Proton (H1) NMR
Integration: Area under the curve/peak is proportional to # of protons
Deshielding: protons occur when e- withdrawing groups pull e- away
Proton (H1) NMR: aldehyde H
9-10 ppm
Proton (H1) NMR: COOH Hs
10.5-12 ppm
Proton (H1) NMR: aromatic Hs
6-8.5 ppm
Chromatography: Stationary vs. Mobile Phase
Stationary: absorbent, usually a polar solid
Mobile: runs through the stationary phase, usually liquid or gas, elutes the sample through the stationary phase
High affinity for the stationary phase =
smaller retardation factors
take longer to pass through
low affinity for the stationary phase =
elute through more quickly
Calculating Rf factor on thin layer chromatography
distance spot moved / distance solvent font moved
