| Terms |
Definitions |
|
C≡N
|
2600cm⁻¹
|
|
chromatography
|
based on bp
|
|
unsaturated
|
pi or ring
|
|
saturated
|
no pi or ring
|
|
increase branching
|
decrease mp & bp
|
|
bromine
|
-more stable (bigger atom)
-more selective (more picky)
|
|
Separation Techniques
|
extraction, precipitation & chrystallization, distillation, flash chromatography
|
|
deshielded
|
downfield --> lower ppm value
increased proximity to EN group deshields a set of protons
|
|
Absolute configuration
|
R-clockwise ; S-counterclockwise
There is no correlation btwn the sign of rotation and the absolute config
|
|
C=O
|
1750cm⁻¹ (very strong and intense sharp peak)
|
|
Diastereomers
|
-they are non-mirror images, have multiple stereocenters, they differ at not all stereocenters
-diff bp, mp, solubility etc
-optically active, but no relationshop to each other
|
|
Stereoisomers
|
the same bond connectivity, diff spatial arrangement of atoms
|
|
levorotatory (-)
|
rotate plane polarized light counterclockwise
|
|
rate of sN1 reaction
|
rate = k[reactant]--onnly carbocation-producing compound is considered, nucleophile is not!
|
|
pI
|
-isoelectric point
-pH at which an aa has a net charge of 0 (zwitterion form)
-avg of all pKa
-if pI > pH, AA carries a (+) charge
|
|
Quarternary Structures
|
3D structures of multiple polypeptide chains ('subunits')
stabilized by H-bonds, disulphide bridges, hydrophobic/phillic interactions and covalent bonds
|
|
electrophile
|
(-) charge seeking, δ⁺, lewis acid (accepts e⁻)
|
|
Polar
|
Ser, Thr, Tyr --> -OH containing groups
Cys (disulfide bridges)
|
|
anomers
|
epimers that result of ring closure
α -OH down
β -OH up
|
|
Proteins
|
-all amino acids are L-aa, chiral and amphoteric
-exception: glycine
|
|
racemic mixtures
|
50-50 mix of enantiomers ; optically inactive
|
|
reducing sugars
|
benedict's test: + in the presence of reducing sugars
eg. aldehydes, ketones, hemiacetals are reducing
all monosaccharides are reducing, di- and polysaccharides w/ hemiacetals anomeric C's
*Sucrose is non-reducing (b/c both anomeric carbons are acetals)
|
|
rate of an sN2 reaction
|
rate = k[substrate][Nu⁻] -- depends on both nucleophile and substrate
|
|
How many stereoisomers?
|
a molecule w/ n stereocenters has 2ⁿ stereoisomers (including itself)
|
|
what is an "ylide" ?
|
also known as a "phosphorane" -- positively-charged phosphorus is the central atom, usually bound to two phenyl groups and a carbon group that is negatively-charged.
|
|
describe an sN2 reaction
|
the lone pair of a nucleophile attacks the "backside" of an electrophilic carbon, displacing the leaving group and inverting the stereochemistry (if there is one to begin with)
|
|
how are grignard reagents produced?
|
R-Br + Mg in diethyl ether yields R-MgBr
|
|
what happens in a wittig reaction
|
the carbonyl group of an aldehyde or ketone is turned into a carbon-carbon double bond by using a nucleophilic ylide to attack the electrophilic carbonyl carbon
|
|
what would happen if a grignard reaction was added to an ester?
|
it would attack the carbonyl group of the ester, forming a ketone which is more reactive than the original ester. the grignard reagent will keep "attacking" until a tertiary alcohol is produced.
|
|
if molecule has no chiral center, then it will have NO optical activity
|
if chiral centers have the same absolute config , then there is no mirror image
|
|
if the hydroxyl group of an alcohol is converted to an inorganic ester, what type of reaction will it likely participate in?
|
an SN2 reaction. this usually involves thionyl chloride (SOCl2) and is used to turn an alcohol into an alkyl halide
|
