-
Enantiomers
Mirror Image isomer, pair of compounds that are nonsuperimposible
-
Achiral
An object that is superimposable (identical) to its mirror image.
-
Diastereomer
Stereoisomers that are not enantiomers
-
Meso Compound
A comund that has multiple but is achiral due to an internal plane of symmetry
-
Stereocenter
Stereogenic center, Asymmetrical carbon atom (w/ four different substiuents)
-
If a compund is chiral it must have....
an enantiomer
-
If a compund has no asymetrical carbons it is...
achiral
-
If a compound has only one asymmetrical carbon atom, it is...
Chiral
-
If a compound has more than one asymmetrical carbon atom, the compound is..
chiral or achiral, it depends.
-
When taking mirror images of CH3 and NH2, they turn into...
H3C and H2N
-
Any molecule that has an internal mirror plane of symmetry cannot be ______, even though it may contain asymmetric carbons.
chiral
-
A carbon with only 3 different substiuents has...
an internal mirror plane
-
Asymmetrical carbon atoma are always
nonsuperimposable
-
Racemic mixture...
A sloution has equal amounts of (+) and (-) solutions so it can be optically inactive. (rotation of 0o)
-
How do you find the Opitcal Purity?
divide the observed rotation by the rotation of the pure enantiomer and multiply by 100%
-
What is the enantomeric excess ?
the optical purity (d-l)/(d+l)
-
Optically active is...
chirality
-
Allenes have two....
double bonds
-
If the mirror image of a compound is the original compound rotated by 180o it is..
the same thing
-
If the mirror image of a compound is the original compound rotated by 90o it is..
an enantiomer
-
In a fischer projection, if the gropus are changed around an odd number of times, it is...
enantiomeric
-
In a fischer projection, if the gropus are changed around an even number of times, it is...
the same thing
-
Molecules with symmetry planes cannot be ...
chiral
-
In a fischer projection, To figure out if the mirror image of a compound in an enantiomer...
rotate the mirror image by 180o and if it does not match the original image, it is an enantiomer.
-
In the fischer projection with one asymmetric carbon, the atom postions in correlation with the perspection drawing from "left" to "up" to "right" to "bottom" are....
- Wedge, Top, Plane, Dash
- "Willie Tells Patty's Details"
-
In the fischer projection with two asymmetric carbons, the atom postions in correlation with the perspection drawing from "topleft" to "top" to "topright" to "bottomright" to "bottom" to "bottom left" are....
- Left Wedge, Left Plane, Left Dash, Right Dash, Right Plane, Right Wedge
- "Will pleases Ducks, Ducks please Will"
-
Alkyl Halide is an...
halogen atom bonded to one sp3 hybrid carbons atom of an alkyl group
-
A vinyl halide is...
Halogen atom bonded to one of the sp2 hybrid carbon atom of an alkene
-
An aryl halide is..
halogen atom bonded to one of the sp2 hybrid carbon atoms of an aromatic ring. (Three double bonds in it)
-
An sp3 hybrid carbon has ____ sigma bonds.
four
-
An sp2 hybrid carbon has ____ sigma bonds.
three
-
An sp hybrid carbon has ____ sigma bonds.
two
-
What is the IUPAC nomeclature template for an alkyl halide?
- Haloalkane
- Halogen + Alkane (Bromo-propane)
-
What is the trival/common nomeclature template for an alkyl halide?
- Alkylhalide
- Alkyl + Halide (Isopropyl Bromide)
-
CH2X2 is a...
Methylene Halogen
-
-
CX4 is a...
Carbon Tetrahalide
-
If a halogen carbon atom is bonded to one carbon atom it is a ...
Primary Halide = 1o
-
If a halogen carbon atom is bonded to two carbon atoms it is a ...
Secondary Halide = 2o
-
If a halogen carbon atom is bonded to three carbon atoms it is a ...
Tertiary Halide = 3o
-
If a halogen carbon atom is bonded to no carbon atoms it is a ...
methylhalide
-
Geminal dihalide is a...
two halogen atoms bonded to some carbon
-
Vicinal dihalide is a ...
Two halogen atoms bonded to adjacent carbon atoms
-
Halogen is always more _____ than carbon
electronegative
-
The dipole of CX4 is always...
0
-
The strongest attraction in akyl halides is..
London forces
-
In alkyl halides, the larger the surface area, the _____ the attraction.
Stronger
-
In alkyl halides, the stronger the attraction, the _____ the boiling point...
Higher
-
In alkyl halides, Dipole-Dipole attractions affect the boiling point at a _____ extent.
smaller.
-
Higher molecular weight = ______ boiling point
higher
-
Branched and spherical compounds have a _____ boiling point.
lower
-
Alkyl bromides/iodides are ______ than water.
Denser
-
Alkyl chlorides are ______ than water.
less dense
-
Alkyl fluorides are ______ than water.
less dense
-
Alkyl chlorides (2 or more cl atoms) are ______ than water.
denser
-
Allylic position is...
A carbon atom next to a carbon-carbon double bond
-
Intermediates are...
cations, radicals, anions (stabilized by ressonance w/ double bonds) = charge/radical delocalized
-
What is allylic bromination?
When Br2 takes an allylic hydrogen atom to leave a resonance-stablilized allylic radical. The radical then reacts with Br2 to regenerate a Bromine radical that continues a chain reaction.
-
List the steps of allylic bromination.
- Bromine absorbs light, causing formation of radicals.
- A bromine radical abstracts an allylic hydrogen. (Leaving an allylic radical and HBr)
- Either radical carbon can react with bromine. (Leaving an allylic bromide (and a possible allylic shift) and a bromide ion- )
-
When something replaces the halogen ion it is .....
substiution
-
When the halide ion leaves with another atom is ....
elimination
-
dehydrohalogenation is a kind of...
elimination
-
in eliminations, a lost of H--X from alkyl halide gives...
an alkene.
-
When a elimination occurs, a ______ is formed.
Pi bond
-
The general nucleophilic substituion form...
Nucleophile + Substrate ---> Product & Leaving Group
-
A donor on an electron pair is...
a nucleophile
-
Something is electrophillic when it...
the atom isbonded to an electronegative atom.
-
Carbons will have a partial positive charge because of...
Halogen's electronegativity
-
Nucleophiles always attack....
Electrophiles
-
The SN2 reaction is _____ order.
Second
-
SN2 has no....
intermediates
-
How many steps does SN2 have?
one
-
What is the order of reactivity for substrates in the SN2 reaction?
CH3 > 1o > 2o >> 3o
-
-
-
R' - COO - R is a....
Ester
-
Halides can be turned into halides by....
Halogen exchnage reactions (flip flopping halogens)
-
When F wants to be a nucleophile what happens?
It can't do it alone, needs a helper (KF/18-Crown-6)
-
If a atom forms a new bond to a proton it's a...
base
-
If a atom forms a new bond to a carbon it's a ....
nucleophile
-
On the P Table, nucleophilicity decreases....
From left right
-
On the P table nucleophilicity increams from
top to bottom
-
As Polarizability increases, nucleophilicity....
increases
-
As electronegativity increases, nucleophilicty ....
decreases
-
If an atom is "soft" it's
Highly polarizable
-
If an atom is "hard" it's
Lowly polarizable
-
Steric Hinderance...
When bulky groups interfere with a reaction by virtue of their size.
-
If you want a base use ...
A bulky reagent
-
If you want a nucleophile use...
less hindered reagent.
-
Protic slovent...
acidic protons usually in the form of O-H or N-H to attach to nucleophiles
-
Small anion _____ nucleophilicity because?
- reduced
- More energy needed to strip off slovent from solvated ion
-
Large anion _____ nucleophilicity because?
- increased
- Less energy used to strip off solvents
-
-
aprotic solvents
solvents with or w/o O-H or N-H (enhances nucleophilicty of anions
-
Why is an anion more reactive in a aprotic solvent?
Not strongly solvated
-
Most polar ionic reagents are insoluble in....
simple aprotic solvents
-
Polar aprotic solvents
strong dipole moments to enhancesolubility (even though no N-H or O-H bonds)
-
In an SN2 reaction, the leaving group's purposes are
- polarize the C-X bond (making carbon electrophile)
- Leaves w/ the pair of electrons that once bonded it to the electrophilic atom.
-
A good leaving group has to be...
stable and electron withdrawing (polarize carbon)
-
Carbon needs to be partially positive to be ...
electrophillic
-
OH is a _____ leaving group
poor
-
A nucleophillic attack on a primary halide is...
easy because unhindered
-
A nucleophillic attack on a secondary halide is...
Possible but hindered
-
A nucleophillic attack on a tertiary halide is...
Impossible....too bulky
-
A neutral molecule can serve as a leaving group from a ......
positively charged species
-
In SN2, the nucleophile does a _______ attack
back-side
-
Solvolysis...
When solvent is nucleophile
-
SN1 reaction rate is ____ order
First
-
List the steps of the SN1 Mechanism..
- 1. Carbocation forms (ionization- rate limiting)
- 2. Nucleophile attacks the carbocation
- 3. Proton is loss to slovent
-
What is the reactivity for SN1?
3o > 2o > 1o > CH3X
-
_______ groups enhance the SN1 Reaction...
alkyl
-
Vinyl and Aryl groups do not undergo ______ reactions.
SN1 and SN2
-
Why can't vinyl or aryl groups undergo an SN1 reaction?
Can't ionize because they are so weak
-
Why can't vinyl or aryl groups undergo an SN2 reaction?
Cannot be attacked, too bulky.
-
For good ion stabilization use a ____ solvent
polar
-
When carbon and the leaving group are being solvated, who gets the oxygen and who gets the hydro?
- Carbon = Oxygen
- Leaving group = Hydro
-
Carbocation is...
intermediate that is sp2 hybridized and planar
-
Retention of configuration happens in...
SN1
-
Retention of configuration happens when...
Nucleophile attacks from the side the leaving group left from.
-
Inversion of configuration happens when ...
Nucleophile attack from the back side
-
What are the steps of racemization in the SN1 reaction?
- 1. Ionization for carbocation
- 2. Nucleophile can attack from bottom or top ( if on top = retention of configuration, if on bottom = inversion of configuartion)
-
Will you find rearrangments in SN1?
Yes
-
Will you find rearrangments in SN2?
No
-
Why is there no rearrangemtns in SN2?
You need a carbocation to rearrange something...SN2 is a one step reaction with no carbocation.
-
Rearrangments result from a ...
hydride shift
-
List the steps of hydride shift in SN1...
- 1. Ionization for a carbon cation
- 2. Shift hydrogen to the carbocation for stability and get a higher degree of carbocation (perferably tertiary)
- 3. Have a solvent attack the new carboncation
- 4. Deprotonize the compound with another molecule of the solvent to leave the new compound with a proton loss and a new solvent moleclue with a proton gain.
-
List the steps of the E1 reaction...
- 1. Ionize (rate-limiting step) to get a carbocation
- 2. Weak base comes and deprotonates the compound
- 3. With empty oribtals, Carbon bonds are forced to form a double bond to compensate the lost of the leaving group and proton, forming an alkene and the protonated base and negative leaving group.
-
Dehydrohalogenation....
Loss of a proton and halogen
-
List the steps of rearrangemnent in the E1 reaction.
- 1. Ionize to get a carbocation
- 2. Hydride shift to form a stable carboncation
- 3. Weak basic solvent removes a proton to make an alkene. Shifting things around can result into multiple compounds witht the bonds in different places.
-
Zaitev's Rule...
In Elimination reactions... The most substituted compound, usually predominates because they are the most stable
-
Explain the steps of the E2 Reaction...
- 1. Leaving group leaves then..
- 2.Strongbase/Nucleophile used for a poor SN2 substrate (something usually hindered, 3o or 2o) takes a proton
-
What is the reactivity for the E2 reaction?
3o > 2o > 1o
-
Eclipsed conformation = _____ energy
higher
-
Staggered conformation = ___ energy
less
-
For E2 the molecule should be .....
Anti-Coplanar
-
Is there any rearrangments in E2?
Nooo
-
If the base/nucleophile is strong (HO- or RO-) what kind of reaction can it be?
SN2 or E2 (second order)
-
If the base/nucleophile is weak (H2O or ROH) what kind of reaction can it be?
SN1 or E1 (first order)
-
If the base/nucleophile is strong (HO- or RO-) and the substrate is primary or methyl what reaction is it?
More SN2 than E2 (E2 can happen w/ higher temperature and a hindered base)
-
If the base/nucleophile is strong (HO- or RO-) and the substrate is secondary what reaction is it?
SN2 and E2 (higher temperature and hindered base favor E2)
-
If the base/nucleophile is strong (HO- or RO-) and the substrate is tertiary what reaction is it?
E2 (SN2 would be extremely slow)
-
If the base/nucleophile is weak (H2O or ROH)and the substrate is primary or methyl, what kind of reaction can it be?
No real reaction. too slow
-
If the base/nucleophile is weak (H2O or ROH)and the substrate is secondary or tertiary, what kind of reaction can it be?
SN1 and E1 (higher temperature and hindered base wants elimination)
-
What is the double bond energy?
611 kJ/mol
-
What is the sigma bond energy?
347 kJ/mol
-
What is the pi bond energy?
264 kJ/mol
-
The more s orbital you have = the _____ bond length
shorter
-
-
How much "s" is in sp2 ?
1/3
-
How much "s" is in sp3?
1/4
-
What is the elements of unsaturation formula?
1/2( 2C + 2 - H)
-
How many elements of unsaturation is a Double bond?
One
-
How many elements of unsaturation is a ring?
One
-
How many elements of unsaturation is a triple bond?
two
-
If an alkene is unsaturated what can you do to it?
add a hydrogen in a catalystic presence
-
What is a saturated alkene?
alkane (cannot react anymore)
-
When determing count for element of unsaturation, halogens are...
Hydrogen
-
When determing count for element of unsaturation, oxygens are...
ignored
-
When determing count for element of unsaturation, nitrogens are...
a half of carbon
-
Nomenclature of the alkenes are like the alkanes just with ____ on the end
"ene"
-
When naming alkenes what the order you should follow?
Substiuents first then double bond position.
-
-
-
-
If a carbon hold two or more of identical groups, there can be no...
Cis or trans
-
In the E-Z system, E is..
Opposite
-
In the E-Z system, Z is ...
the same side
-
How do you assign E and Z?
mentally split the alkene into two parts, on the left assign priority to the two substiuents, then on the right assign the priorities, if "1" of the left and "1" of the right, are directly across from each other it is "Z". If they are diagonal from each other they are "E"
-
To name an alkene by it's common/trival name use..
- the IUPAC name but "yl" to the end of the alky part
- (ethYLene, propYLene)
-
Which are more stable trans or cis?
trans
-
Why is trans more stable then cis?
Because alkyl substiuents and seperated and farther apart in the trans isomer.
-
Less energy means _____ stability.
More
-
Monosubstituted means more ______ and Less _____
-
Tetrasubstituted means more ______ and Less _____
-
If there is more energy it is less stable, meaning more _______
reactivity
-
|
|