MCAT Organic Chemistry 3 Flashcards

Terms Definitions
gem-dihalide
glycerol
ether
alcohol
ozonolysis
O3
carboxylic acid
formaldehyde
(aka methanal)
potassium permanganate
kmno4
Vinyl
monosubstituted ethylene
Alcohol + Aldehyde
Acetal
benzene substituent names
resolution
separation of enantiomers
diol
two hydroxyl groups
anomeric carbon
word for C1
Carboxylic acid derivative examples
C.A.
Ester
Amide
Anhydride
acetic acid
(aka ethanoic acid)
aldoses
aldehyde carbohydrates like glucose
dash line wedge formula
not ignored
iso, neo, cyclo
diastereoisomer
different molecule, not mirror image
splitting
NMR result of neighboring H's
3° Alcohol with Oxidation
No reaction
NMR
(nuclear magnetic resonance) resonance of protons to radiation in a magnetic field; may use carbons as well, but rare on MCAT
prefixes for number of carbons
reducing
zn/h or CH3/s with ozonolysis
Alkyne
carbon carbon triple bonds. Suffix-yne.
quantum numbers
n, l, ml, ms
methylene
refers to the =CH2 group
Seesaw
4 bonds and 1 lone pair
2^n
maximum number of optically active isomers
Oxidations from Alkane to...
1° Alcohol...Aldehyde...C.A.
2° Alcohol...Ketone
3° Alcohol
meso compounds
optically inactive diasteriomers due to chiral centers offsetting each other; they are achiral
extraction
separation based upon solubility due to similar polarities; like dissolves like
tosylate
commonly used sulfonate; weak base, great leaving group
enantiomer
moleculse that have the opposite configuration at their one chiral center. or if multiple chiral centers, must have the opposite configuration at every one of their chiral centers to be enantiomers. identical physical properties and much of the same chemical properties. but differe in optical activity and how they react in a chiral environment
stereoisomers
same chemical formula. same atomic connectivity . different in how atoms are arranged in space
nucleophile
nucleus lover. electron rich species that are attracked to charged atoms
carbonyl
carbon double bonded to an oxygen
isomer
same molecular formula but different structure
epimers
diasteroisomers with 1 a carbon that has one different configuration (ex: beta and alpha glucose)
Decarboxylation
-when a C.A. loses CO₂
-reaction is usually exothermic, the Ea is usually high, making the reaction difficult to carry out.
-Ea ⬇ when the β C is a carbonyl because either the anion intermediate is stabilized by resonance or the acid forms a more stable cyclic intermediate.
Geometric Isomers
- have diff physical properties
Cis: has dipole, stronger IM forces, high BP, not as readily crystalizes, Lower MP
Trans: no dipole, weaker IM forces, lower BP, more readily crystalizes, higher MP
transesterification
reaction in which alcohol reacts with an ester to form another ester (with a different R group) through nucleophilic substitution
electrostatic force
attraction of positive and negative charges
instantaneous dipole moment
dipoles within otherwise nonpolar molecules as electrons move throughout the orbitals
hydroboration
diborane add to double bond. boron acts as lewis acid and attaches to less hindered carbon. hydride transferred to adjacent carbon. antimarkonikov, alcohol produced
protic solvent
solvents with protons in solution, e.g. water or alcohol. large atoms tend to be better nucleophiles in here because they can shed the solvating protons around them and are more polarizable
oxidation
if reagent has a bunch of oxygen
oxidizing
ozonolysis under hot acidic kmO4, e.g. H2O2 condition
geminal
diol with hydroxyl group on same carbon
peroxycarboxylic acid
alkene oxidized with this, strong oxidizing agent. CH3CO3H or mcpba and it makes epoxide or oxirane
Alkane
Chain of carbons connected by single bonds with hydrogen atoms attached.
electron withdrawing groups
includes the groups: -NO2, -NR3+, -CCl3, -COR, -COH, -COOR, -COOH, -SO4H, -CN
Bond energy
- energy necessary to break a bond
Synthesis of Alcohols
- organometallic reagents possess a highly polarized carbon-metal bond
- C is more electronegative than the metal, so C takes on a δ- charge
- the polarized C-metal bond and the δ- charge on C makes the C a strong nuke/base
- most common reaction for organometallic is a nuke attack on a carbonyl C, after which an acid bath = alcohol.
Important valences for O-Chem
Carbon - tetravalent
Nitrogen - trivalent
Oxygen - divalent
Hydrogens / Halogens - monovalent
Halogens (other than F) are capable of making more than one bond
Hoffman Degradation
** the advantage of the Hoffman Degradation over other methods of producing amines is that other methods rely on Sn2 --> this prevents the production of amines on a 3° C.
- The hoffman can produce 1°, 2° or 3° alkyl position.
Mechanism:
- 1° amides react with strongly basic solutions of Cl or Br from 1° amines with CO₂ as a biproduct
- the amide is deprotonated by a strong base
- the deprotonated amide picks up a halogen atom leaving a halide ion.
- the product is an N-Haloamide
- the N-haloamide is more acidic than the original 1° amide and is deprotonated as well
- trick rearrangement: R group of amide migrates to the N to form an isocynate
- Isocynate reacts with water forming a carbonic acid.
- carbonic acid is decarboxylated giving of CO₂
aldol condensation
occurs when one aldehyde reacts with another, one ketone reacts with another, or when an aldehyde reacts with a ketone
electrophilic addition
reaction that adds an electrophile to an alkene or alkyne
relative configuration
two molecules that differ about a carbon by only one substituent, but all else is the same
keto-enol tautomers
a reaction at equilibrium involving a proton shift that a ketone or aldehyde exists as at room temperature
specific rotation
a = observed rotation / concentration * length
catalytic hydrogenation
reducing an alkene by adding molecular hydrogen to double bond with aid of metal catalyst. e.g. pt, pd, ni. takes place on surface of metal so it does syn addition
eclipsed conformation
highest energy no separation. or 120 separation.
angle strain
when bond angles deviate from ideal values
A solution of 200mg of the R enantiomer of a substance had an observed rotation of a=8 degrees. If 50mg of the S enantiomer of the substance is dissolved into the same solution, the new observed rotation that would be measured would be: A. -8 degrees, B.
C
Acetoacetic Ester Synthesis
- production of a ketone from acetoacetic ester due to the strongly acidic properties of the α H.
- A base is added to remove the α H's.
Nucleophilicity
- ⬇ as going from ⬈ on periodic table
- strength of nuke: unimportant for Sn1, important for Sn2
Oxidation of Alkenes
- may produce glycols (hydroxyl groups on adjacent carbons) or cleave the alkene at the double bond of ozonalysis
- alkynes produce C.A. with undergoing ozonalysis
Halogenation
- Halogens add to ketones at the alpha C in the presence of base or acid.
- when base used: difficult to prevent halogenation at more than 1 of the alpha positions.
- base is also consumed by the reaction with water as a by-product, whereas the acid acts as a true catalyst and is not consumed.
- when a base is used with a methyl ketone, the alpha carbon will be completely halogenated.
Sigma Bonds
- Strong bonds with lowest energy and most stable form of covalent bond
enolate ion
an aldehyde or ketone that has lost its α-hydrogen; the anion is stabilized by resonance
Hofmann elimination
a reaction with an amine creating an alkene; the major product is the least stable alkene called the Hofmann product
Markovnikov's rule
the hydrogen will add to the least substituted carbon of the double bond in an electrophilic addition reaction (anti-Markovnikov is the opposite)
hot, acidic potassium permanganate
nonterminal alkenes are cleaved to form two molar equivalent of carvoxylic acid ..make keton
saturated hydrocarbon
no double bonds. it has the maximum number of hydrogens.
What is a diastereomer?
Stereoisomers that are not mirror images.
Reverse Aldol Condensation
- Example is the 4th step of glycolysis:
the six-carbon β-hydroxyketone breaks into two three-carbon fragments. After neutralization, are DHAP and G-3-P.
- the enzyme responsible is aldolase
Pinacol Rearrangement
- conversion of a vicinal diol into a ketone in acid
selectivity (referring to halogenation)
how selective a halogen radical is when choosing a position on an alkane
isoelectric point
pH at which there is no net charge; electrically neutral
Which creates the strongest acid: tertbutanol, butanol, or secbutanol?
Tertbutanol since the inductive effects of the three methyl groups cause a slightly greater stabilization effect of the conjugate base.
Oxidation of alcohols
- Loss of H₂
- Addition of O or O₂
- Addition of X₂
Single photon can be described as
- changing electric field and corresponding magnetic field
- both are perpendicular to each other and the direction of propagation
dehydration of an alcohol
an E1 reaction where an alcohol forms an alkene in the presence of hot acid; the rate is dependent on the alcohol
electrophilic addition of H2O
water can be added to alkenes under acidic conditions. make carbocation. ends with alcohol
Sn1 characteristics and steps
- 2 steps
- rate dependent on only 1 of the R
1. formation of C+
- this is the slow step ∴ rate determining step
- rate = k [substrate]
- substrate is the electrophile or the molecule being attacked
2. very quick. the nuke attacks the C+
Unsaturated Fatty Acid with H₂ or FADH₂
Saturated Fatty Acid
Double bond to single bond
What is more stable, a highly substituted alkene or the same alkene with only hydrogen substituents?
The more highly substituted alkene gives off the lowest heat of hydrogenation and therefore is more stable.
The more S character a bond has...
- the more stable, stronger and shorter it is
electrophilic addition of HX
e of double bond act as lewis base and react with hydrogen of hx. make carbocation intermediate. use markonikovs rule
4 main types of reactions in o-chem
- Addition (A + B ---> C)
- Elimination (A ---> B + C)
- Substitution (A-B + C-D ---> A-C + B-D)
- Rearrangement (A ---> B)
Chemical Properties of Aldehydes and Ketones
- most of the time will act as the Substrate in Nucleophilic Addition or as a B-L acid by donating one of its α H's.
- Alkyl groups are e' donating.
- Ketone has 2 alkyl groups attached to carbonyl, the carbonyl of the conjugate base of the ketone is less able to distribute the - charge and is slightly less stable than that of an aldehyde.
∴ aldehyde is more acidic than ketone
∴ more reactive than ketone
rules to detemine if oxidation occurred
1. loss of H2
2. addition of O or O2
3. addition of X2 (halogens)
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