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OCHEM Test 2
OCHEM Test 2
280
Organic Chemistry
Undergraduate 2
06/05/2017

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Term
enantiomers
Definition
mirror-image isomers
Term
the reason for handedness in molecules:
Definition
chiralty
Term
chiral molecules
Definition
molecules that contain no plane of symmetry and are not superimposeable on their mirror-images
Term
chirality center
Definition
a C bonded to 4 different groups
Term
some groups that can't be chirality centers
Definition
-CH2- -CH3 C=O C=C C≡C
Term
optically active substances
Definition
substances that, when in solution, rotate the plane of plane-polarized light
Term
the angle of rotation of optically active substances can be measured with...
Definition
a polarimiter
Term
some things about a substance's rotation that can be measured
Definition
-angle
-direction
Term
dextrorotary compound
Definition
a compound whose solution rotates plane-polarized light to the right
Term
levorotary compound
Definition
a compound whose solution rotates plane-polarized light to the left
Term
the extent of rotation depends on...
Definition
-concentration
-path length
-wave length
Term
specific rotation
Definition
the optical rotation of a chiral compound under standard conditions, such as concentration of 1g/mL, sample path length of 1 dm, and light of wavelength 589 nm
Term
rules for assigning configurations at a chirality center
Definition
1: assign priorites to each group bonded to the C by using Cahn-Ingold-Prelog rules
2: orient the molecule so that the group of lowest priority is pointing to the rear
3: draw a curved arrow from group 1 to group 2 to group 3
4: if the arrow rotates clockwise, the chirality center is R, and if the arrow rotates counterclockwise, the chirality center is S
Term
how to assign priorites to each group bonded to the C by using Cahn-Ingold-Prelog rules
Definition
1: rank each atom by atomic number (atoms with higher atomic numbers get higher priorities)
2: if a decision can't be reached based on the first atom, look at a second or third atom until a difference is found
3: multiple bonded atoms are equivalent to the same number as single bonded atoms
Term
is the sign of optical rotation related to R, S designation?
Definition
no
Term
how R, S designations have been proven to be correct
Definition
X-ray experiments
Term
a molecule with 2 chirality centers can have how many possible stereoisomers?
Definition
4
Term
depiction of the relationship between enantiomers and diastereoisomers
Definition
photograph figure 5-10 on p. 131
Term
diastereoisomers
Definition
stereoisomers that are not mirror images
Term
epimers
Definition
diastereoisomers whose configuration differs at only 1 chirality center
Term
meso compound
Definition
occurs when a compound with 2 chirality centers possesses a plane of symmetry
Term
a meso compound is ______ despite having 2 chirality centers
Definition
achiral
Term
a meso compound is achiral despite ______
Definition
having 2 chirality centers
Term
racemic mixture (racemate)
Definition
a 50:50 mixture of 2 enantiomers
Term
the optical rotation of racemic mixtures
Definition
zero
Term
constitutional isomers
Definition
differ in connections between atoms
Term
skeletal isomers
Definition
have different C skeletons
Term
functional isomers
Definition
contain different functional groups
Term
positional isomers
Definition
have functional groups in different positions
Term
stereoisomers
Definition
have the same connections between atoms, but different geometry
Term
types of diastereoisomers
Definition
-configurational diastereoisomers
-cis-trans isomers
Term
how cis-trans isomers differ
Definition
they differ in the arrangement of substituents on a ring or a double bond
Term
other elements that can be chirality centers
Definition
other elements wit tetrahedral atoms
Term
prochiral
Definition
able to be converted from achiral to chiral in a single chemical step
Term
how to identify prochirality for a sp2 hybridized C
Definition
1: draw the plane that includes the atoms bonded to that sp2 C 2: assign priorities to the groups bonded to that C 3: draw a curved arrow from group 1 to group 2 to group 3 4: the face of the plane on which the curved arrow rotates clockwise is the Re face 5: the face on which the arrow rotates counterclockwise is the Si face
Term
when an atom that is sp3 hybridized has a prochirality center
Definition
when it becomes a chirality center after one of its attached groups is replaced
Term
how to identify prochirality in an sp3 hybridized atom
Definition
1: for CH2X, imagine a replacement of 1 H with deuterium 2: rank the groups, including deuterium 3: if the replacement leads to R chirality, the atom is pro-R 4: if the replacement leads to S chirality, the atom is pro-S
Term
when a C is not a stereocenter
Definition
when it has 2 of the same group attached to it
Term
how to determine whether the stereocenter has the R or S configuration
Definition
1: give each of the 4 groups a number (1-4)
2: use the orientation of these numbers to determine the configuration
Term
how to assign numbers to the groups around a stereocenter
Definition
1: make a list of the 4 atoms attached to the stereocenter
2: rank those atoms based on atomic number
Term
meso compound
Definition
compound that has an internal plane of symmetry
Term
when compounds are chiral
Definition
when they have stereocenters and they and are not meso
Term
+ rotation
Definition
compound makes plane polarized light rotate clockwise
Term
- rotation
Definition
compound makes plane polarized light rotate counterclockwise
Term
dextrorotary
Definition
rotates polarized light clockwise

given a minus (+) sign
Term
levorotary
Definition
rotates polarized light counterclockwise

given a minus (-) sign
Term
the number of stereoisomers a molecule with chirality centers can have
Definition
2n stereoisomers, where n = # of chirality centers
Term
pro-R
Definition
atom whose replacement leads to an R chirality
Term
pro-S
Definition
atom whose replacement leads to an S chirality
Term
Re face
Definition
the face on which the arrows curve clockwise
Term
Si face
Definition
the face on which the arrows curve counterclockwise
Term
types of organic reactions
Definition
-addition
-elimination
-substitution
-rearrangement
Term
addition reactions
Definition
occur when 2 reactants add to form one product, with no atoms left over

A + B --> AB
Term
elimination reactions
Definition
occur when a single reactant splits into 2 products

AB --> A + B
Term
substitution reactions
Definition
occur when 2 reactants exchange parts to yield 2 new products

AB + CD --> AD + CB
Term
rearrangement reactions
Definition
occur when a single product undergoes a rearrangement of bonds to yield an isomeric product

ABCD --> DBCA
Term
reaction mechanism
Definition
describes the bonds broken and formed in a chemical reaction, and accounts for all reactants and products
Term
types of bond breaking in chemical reactions
Definition
-homolytic
-heterolytic
Term
homolytic bond breaking
Definition
symmetrical bond breakinbg such that 1 electron remains with each fragment
Term
depiction of homolysis
Definition
Term
heterolytic bond breaking
Definition
unsymmetrical bond breaking such that both electrons remain with one fragment and the other fragment has a vacant orbital
Term
depiction of heterolysis
Definition
Term
types of bond formation in chemical reactions
Definition
-symmetrical
-unsymmetrical
Term
symmetrical bond formation
Definition
each reactant contributes 1 electron to a covalent bond
Term
depiction of symmetrical bond formation
Definition
Term
unsymmetrical bond formation
Definition
both electrons in a covalent bond come from 1 reactant
Term
depiction of unsymmetrical bond formation
Definition
Term
types of reactions
Definition
-radical
-polar
-pericyclic
Term
radical reactions
Definition
involve symmetrical bond breaking and bond formation
Term
polar reactions
Definition
involve unsymmetrical bond breaking and bond formation
Term
radical
Definition
reactant that contains an atom with an unpaired electron
Term
why radicals are highly reactive
Definition
because they contain an atom with an unpaired electron
Term
substitution reaction that involves a radical
Definition
occurs when a radical abstracts an atom and a bonding electron from another molecule
Term
addition reaction that involves a radical
Definition
occurs when a radical adds to a double bond
Term
steps in a radical reaction
Definition
-initiation step
-propagation steps
-termination step
Term
initiation step
Definition
produces radicals by the symmetrical clevage of a bond
Term
propagation steps
Definition
chain reaction where a radical abstracts an atom to produce a new radical and a stable molecule
Term
termination step
Definition
when 2 radicals combine
Term
how bond breaking and formation works in radical reactions
Definition
all bonds are formed and broken by reactions of species with odd numbers of electrons
Term
some characteristics of polar reactions
Definition
-they occur as a result of differences in bond polarities within molecules
-electron-rich sites in 1 molecule react with electron-poor sites in another molecule
-the movement of electron pairs is shown by curved, fullheaded arrows
-the reacting species are nucleophiles and electrophiles
-many polar reactions can be explained in terms of acid-base reactions
Term
polar reactions occur as a result of...
Definition
differences in bond polarities within molecules
Term
the polarities within polar molecules are usually due to...
Definition
electronegativity differences between atoms
Term
electronegativity differences may also be due to...
Definition
-interactions of functional groups with solvents
-interactions of functional groups with Lewis acids or bases
Term
if there's no real electronegativity difference between atoms in a molecule, how can that bond behave as a polar bond?
Definition
some bonds in which 1 atom is polarizeable may also behave as polar bonds
Term
the sites that react in polar reactions
Definition
the electron-rich sites in one molecule react with the electron-poor sites in another molecule
Term
the movement of an electron pair in a polar reaction is shown by...
Definition
a curved, fullheaded arrow
Term
the reacting spevcies in a polar reaction
Definition
-nucleophile
-electrophile
-some compounds behave as both nucleophiles and electrophiles
Term
nucleophile
Definition
compound with electron-rich atom
Term
electrophile
Definition
compound with electron-poor atom
Term
many polar reactions can be explained in terms of...
Definition
acid-base reactions
Term
an example of a polar reaction
Definition
addition of HBr to ethylene
Term
what type of addition is the addition of HBr to ethylene?
Definition
electrophilic addition
Term
the behavior of the π electrons in ethylene in the addition of HBr to ethylene
Definition
the π electrons in ethylene behave as a nucleophile
Term
how the reaction of the addition of HBr to ethylene begins
Definition
the attack of the π electrons on the electrophile H+
Term
what happens at the end of the reaction of the addition of HBr to ethylene?
Definition
the resulting intermediate carbocation reacts with Br- to form bromoethana
Term
rules for using curved arrows in polar reaction mechanisms
Definition
-electrons must move from nucleophile to electrophile
-nucleophile can be negative or neutral
-electrophile can be positive or neutral
-the octet rule must be followed
Term
how chemical reactions can be expressed as equilibria
Definition
all chemical reactions are equilibria that can be expressed by an equilibrium constant (Keq) that shows the ratio of products to reactants
Term
when Keq > 1
Definition
[products] > [reactants]
Term
when Keq < 1
Definition
[products] < [reactants]
Term
what must the energy be for the reaction to proceed as written?
Definition
to proceed as written, the energy of the products must be lower than the energy of the reactants
Term
the energy change that occurs during a reaction is described by...
Definition
ΔG°, the Gibbs free-energy change
Term
favorable reaction (spontaneous)
Definition
have negative ΔG° and are exothermic
Term
unfavorable reaction (nonspontaneous)
Definition
have positive ΔG° and are endothermic
Term
the relationship between ΔG° and Keq
Definition
ΔG° = -RT ln Keq
Term
ΔH°
Definition
enthalpy, which is a measure of the total change in bonding energy during a reaction
Term
if ΔH° is negative,...
Definition
the reaction is exothermic
Term
if ΔH° is positive,...
Definition
the reaction is endothermic
Term
ΔS°
Definition
entropy, which is a measure of the freedom of motion of a reaction
Term
rxn with positive entropy
Definition
produces 2 product molecules from 1 reactant molecule
Term
rxn with negative entropy
Definition
produces 1 product molecule from 2 reactant molecules
Term
relationship between ΔG°, ΔH°, and ΔS°
Definition
ΔG° = ΔH° - TΔS°
Term
bond dissociation energy (D)
Definition
measures the heat needed to break a bond to produce 2 radical fragments
Term
what happens to the strength of bonds in exothermic reactions?
Definition
the bonds formed are stronger than the bonds broken
Term
what reaction energy diagrams show
Definition
the energy changes that occur during a reaction
Term
how a reaction energy diagram is set up
Definition
vertical axis represents energy changes and horizontal axis represents the progress of the reaction
Term
the highest energy species in a reaction
Definition
the transition state
Term
can a reaction have more than 1 transition state?
Definition
yes
Term
the energy of activation (ΔG)
Definition
the difference in energy between the reactants and the transition state
Term
values of ΔG range from...
Definition
40-150 kj/mol
Term
what a reaction can do after reaching the transition state
Definition
it can go on to form products or revert to starting material
Term
intermediate
Definition
in a reaction of at least 2 steps, this is the species that lies at the energy minimum between 2 transition states
Term
energy of an intermediate
Definition
even though it lies between 2 transition states, it is a highg energy species
Term
can an intertmediate be isolated?
Definition
usually can't
Term
the solvents laboratory reactions are carried out in
Definition
organic solvents
Term
the medium biological reactions occur in
Definition
aqueous medium
Term
the temperatures laboratory reactions take place in
Definition
a wide range of temperatures
Term
the temperatures biological reactions take place in
Definition
the temperature of the organism, usually within narrow limits
Term
the catalyzing in laboratory reactions
Definition
uncatalyzed or use simple catalysts
Term
the catalyzing in biological reactions
Definition
enzyme catalyzed
Term
description of laboratory reagents
Definition
usually small and simple
Term
description of biological reagents
Definition
involve large, complex coenzymes
Term
specificity of biological reactions
Definition
they have high specificity for substrate
Term
specificity of laboratory reactions
Definition
they are relatively nonspecific
Term
are atoms w/ vacant orbitals electrophiles or nucleophiles?
Definition
electrophiles
Term
a type of rxn that has a carbocation intermediate
Definition
polar rxn
Term
Keq of endergonic rxns
Definition
<1
Term
Keq of exergonic rxns
Definition
>1
Term
activation energy vs. speed of rxn
Definition
the higher the activation energy, the slower the rxn
Term
are pi bonds electrophiles or nucleophiles?
Definition
nucleophiles
Term
are aromatic rings electrophiles or nucleophiles?
Definition
nucleophiles
Term
the difference between exothermic and exergonic
Definition
exothermic = -ΔH°
exergonic = -ΔG°
Term
the difference between endothermic and endergonic
Definition
endothermic = +ΔH°
endergonic = +ΔG°
Term
location of transition state in energy diagram
Definition
peak or curve
Term
location of intermediate in energy diagram
Definition
valley of curve
Term
alkene
Definition
hydrocarbon that contains a C=C bond
Term
the 2 most important organic chemicals produced industrially
Definition
ethylenen and propylene
Term
how ethylene, propylene, and butylene are synthesized
Definition
by thermal cracking
Term
thermal cracking
Definition
involves homolytic breaking of C-H and C-C bonds
Term
thermal cracking reactions are dominated by...
Definition
entropy
Term
degree of unsaturation
Definition
describes the number of multiple bonds and/or rings in a molecule
Term
how to calculate the degree of unsaturation of a compound
Definition
1: determine the equivalent hydrocarbon formula of the compound
2: add the number of halogens to the number of H's
3: subtract 1 H for every N
4: ignore the number of O's
5: calculate the number of paire of H's that would be present in an alkane that has the same number of C's as the equivalent hydrocarbon of the compound of interest. te difference is the degree of unsaturation.
Term
how to name alkenes
Definition
1: find the longest chain containing the 2bl bond, and name it using "ene" as the suffix 2: number the C atoms in the chain, beginning at the end nearer the double bond 3: number the substituents and write the name 4: for cycloalkenes, the double bond is between C1 and C2, and substituents receive the lowest possible numbers 5: a -CH2- substituent is a methylene group, a H2C=CH- group is a vinyl group, and a H2C=CHCH2- group is an allyl group
Term
the hybridization of VC atoms in a double bond
Definition
sp2 hybridized
Term
the bonds formed in the 2bl bond between 2 C's
Definition
1 sigma bond and 1 pi bond
Term
does free rotation occur around 2bl bonds?
Definition
no
Term
cis isomer of an alkene
Definition
disubstituted alkene that has substituents on the same side of the double bond
Term
trans isomer of an alkene
Definition
disubstituted alkene that has substituents on different sides of the double bond
Term
do cis and trans isomers of alkenes interconvert?
Definition
no because of the rigidity of the 2bl bond
Term
when cis-trans isomerism in an alkene doesn't occur
Definition
when one C in the 2bl bond is bonded to identical substituents
Term
what the E, Z system of isomerism is used for
Definition
it's used to describe the arrangement of substituents around a 2bl bond that can't be described by the cis/trans system
Term
rules for E, Z isomers
Definition
1: for each 2bl bonded C, rank its substituents by atomic number (kinda like you assign priorities in R and S configurations)
2: if a decision can't be reached based on the 1st atom, look at the 2nd or 3rd atom until a difference is found
3: multiple bonded atoms are equivalent to the same number of single bonded atoms
Term
Z isomer of an alkene
Definition
has the higher ranked groups on the same side of the 2bl bond
Term
E isomer of an alkene
Definition
has the higher ranked groups on opposite sides of the double bond
Term
which alkenes are more stable, cis or trans?
Definition
trans
Term
why are trans alkenes more stable than cis alkenes?
Definition
because cis alkenes have steric strain between the double bond substituents
Term
stabilities of alkenes can be determined experimentally by measuring...
Definition
-cis-trans e'librium constants
-heats of hydrogenation
Term
the most useful method for determining the stability of alkenes
Definition
by measuring the heats of hydrogenation
Term
heat of hydrogenation of a cis isomer vs that for a trans isomer
Definition
the heat of hydrogenation of a cis isomer is a larger negative number thatn the heat of hydrogenation of a trans isomer
Term
which alkene is of higher energy, cis or trans isomer?
Definition
cis
Term
alkene 2bl bonds become more stable with...
Definition
increasing substitution
Term
why alkene 2bl bonds become more stable with increasing substitution
Definition
-hyperconjugation -more substituted double bonds have more of the stronger sp2-sp3 bonds
Term
hyperconjugation
Definition
stabilizing interaction between the antibonding pi orbital of the C-C bond and a filled C-H sigma orbital oh an adjacent substituent
Term
electrophilic addition reactions
Definition
addition of an electrophile to a C=C bond to yield a saturated product
Term
mechanism of the electrophilic addition of H-X to alkenes
Definition
1: the electrons of the nucleophilic pi bond attack the H atom of the electrophile H-X (X = Cl, Br, I, OH) 2: 2 electrons from the pi bond form a new sigma bond between -H and an alkene C 3: the carbocation intermediate reacts with X- to form a C-X bond
Term
description of the energy diagram for the electrophilic addition of H-X to alkenes
Definition
-has 2 peaks separated by a valley (carbocation intermediate)
-the reaxtion is exothermic
-the first step is slower than the second step
Term
Markovinikov's rule of orientation of addition reactions
Definition
-in the addition of HX to a double bond, H attaches to the C with fewer substituents and X attaches to the C with more substituents (regiospecific)
-if the C's have the same number of substituents, a mixture of products results
Term
regiospecific
Definition
describes a reaction that occurs with a specific regiochemistry to give a single product rather than a mixture of products
Term
the structure of carbocations
Definition
planar; the unoccupied p orbital extends above and below the plane containing the cation
Term
the stability of carbocations increases with...
Definition
increasing substitution
Term
carbocation stability can be measured by...
Definition
studying gas phase dissociation enthalpies
Term
carbocations can be stabilized by...
Definition
-inductive effects ofg neighhboring alkyl groups
-hyperconjugation
Term
how a carbocation can be stabilized by hyperconjugation
Definition
the mnore alkyl groups on the carbocation, the more opportunities there are for hyperconjugation
Term
the Hammond postulate
Definition
postulate stating that we can get a picture of what a given transition state looks like by looking at the structure of the nearest stable species
Term
exothermic reactions have transition states that resemble...
Definition
reactant
Term
endothermic reactions have transition states that resemble...
Definition
product
Term
why the transition state for an endothermic step resembles the product of that step
Definition
because it is closer in energy
Term
why the transition state for an exothermic step resembles the reactant of that step
Definition
because it is closer in energy
Term
in an electrophilic addition reaction, the transition state for alkene protonation resembles...
Definition
the carbocation intermediate
Term
more stable carbocations form faster because...
Definition
their transition states are also stabilized
Term
reactions in which products from carbocation rearrangements are formed
Definition
some electrophilic addition reactions
Term
the formation of products from carbocation rearrangements supports...
Definition
the 2 step electrophilic addition mechanism, in which an intermediate carbocation is formed
Term
how intermediate carbocations can rearrange to more stable carbocations
Definition
-a hydride shift
-an alkyl shift
Term
hydride shift
Definition
the shift of a H atom and its electron pair to a nearby cationic center
Term
alkyl shift
Definition
the shift of an alkyl group with its electron pair to a nearby cationic center
Term
why a compound with an OH group has a higher boiling point than an otherwise identical compound with a lone O
Definition
because of H bonding
Term
stability vs. ΔHcombustion
Definition
inversely proportional
Term
energy of bond vs. size of atoms involved
Definition
inversely proportional
Term
what kind of addition is it when alkene double bonds add to a carbocation?
Definition
electrophilic addition
Term
how rings contribute to unsaturation
Definition
each ring is an extra degree of unsaturation
Term
when numbering the carbons in a chain, what gets priority? functional group or branching?
Definition
functional group
Term
when to put a number next to the E or Z
Definition
when there's more than 1 alkene in a chain
Term
nucleophilic substitution
Definition
swapping of 1 functional group for another
Term
rate of nucleophilic substitution reaction depends on...
Definition
concentration of both nucleophile and alkyl halide
Term
solvents in which reaction occurs faster
Definition
polar protic solvents
Term
rate law for nucleophilic reactions
Definition
rate = k [substrate][nucleophile]
Term
why polar solvents are better thannonpolar solvents for reactions to occur in
Definition
because of the charges involved
Term
types of polar solvents
Definition
-polar protic
-polar aprotic
Term
polar protic solvent
Definition
has O-H or N-H bonds
Term
polar aprotic solvent
Definition
bas a dipole moment but can't H bond
Term
why the reactivity of halides in polar aprotic solvents reverses (F- > Cl- > Br- > I-)
Definition
because there is no H bonding to solvent
Term
what makes a good leaving group?
Definition
leaving groups are weal bases
Term
steric bulk on a particular atom vs. that atom's nucleophilicity
Definition
inversely proportional
Term
elimination reaction
Definition
the loss of a leaving group from the alpha C and a H from the beta C resulting in the formation of a double bond
Term
why the major product of an elimination reaction is the more substituted alkene
Definition
because alkenes become more thermodynamically stable as C-H bonds are replaced with C-C bonds
Term
periodic trand in bacisity
Definition
northwest
Term
anti (stereochemistry)
Definition
2 groups on adjacent C's oriented at 180° to each other

[image]
Term
syn (stereochemistry)
Definition
2 groups on adjacent C's oriented 0° to each other

[image]
Term
gauche
Definition
2 groups on adjacent C's oriented 60° to each other

[image]
Term
eclipsed (stereochemistry)
Definition
when all 3 substituents overlap completely with all 3 substituents on a neighboring C

[image]
Term
staggered (stereochemistry)
Definition
when all 3 substituents on a C are arranged at a 60° angle to all 3 substituents on another C

[image]
Term
racemic mixture
Definition
50:50 mixture of 2 enantiomers
Term
meso compound
Definition
molecule with chiral centers, but has a plane of symmetry that makes the molecule achiral
Term
torsional strain
Definition
strain that arises from the proximity of bonds (and the electrons in them) - generally eclipsing
Term
difference between conformational isomers
Definition
3D shape
Term
physical properties of conformational isomers
Definition
identical, as long as they can interconvert thru bond rotation
Term
difference between constitutional isomers
Definition
different connectivity
Term
physical properties of constitutional isomers
Definition
different boiling points, melting points, and other physical properties
Term
difference between stereoisomers
Definition
configuration
Term
physical properties of enantiomers
Definition
identical, but differ in optical rotation
Term
physical properties of diastereomers
Definition
different boiling points, melting points, etc.
Term
another name for stereoisomers
Definition
configurational isomers
Term
what happens to the axial and equatorial groups when the chair flips?
Definition
the axial groups become equatorial and the equatorial groups become axial
Term
free radicals
Definition
atoms or molecules that contain an unpaired electron in their valence shell
Term
why free radicals are highly reactive
Definition
because they contain less than a full octet of electrons
Term
charge of free radicals
Definition
formal charge zero
Term
what stabilizes free radicals?
Definition
the same factors that stabilize carbocations

-substitution
-resonance
-with adjacent lone pairs
-polarizability
-hybridization
-electron-withdrawing groups
Term
electron-poor species, like radicals, are stabilized by...
Definition
electron rich neighbors or being able to spread electron density over a greater volume
Term
substituted radicals in order of stability
Definition
tertiary > secondary > primary > methyl radical
Term
how resonance can stabilize radicals
Definition
radicals are stabilized if they can be delocalized over several atoms (as in resonance)
Term
how adjacent lone pairs stabilize free radicals
Definition
hyperconjugation

stability increases with increasing donor ability of atom with lone pairs
Term
how polarizability stabilizes free radicals
Definition
stability increases with increasing size of the atom
Term
how hybridization affects free radical stability
Definition
stability increases with decreasing s-character, which moves the free radical further from the nucleus
Term
stability of free radical vs. s-character
Definition
inversely proportional
Term
electron-withdrawing groups
Definition
groups that withdraw electron density from the free radical (without being able to donate a lone pair); they destabilize radicals
Term
bond strength vs. kcal/mol
Definition
directly proportional
Term
how electron movement is shown in homolytic cleavage
Definition
using "single-barbed" arrows
Term
the arrows used to show electron movement in resonance of free radicale
Definition
single barbed arrows
Term
the 3 key mechanistic steps in free radical halogenation
Definition
-initiation
-propagation
-termination
Term
initiation phase of free radical halogenation
Definition
homolytic cleavage of bond between halogen atoms
Term
propagation phase of free radical halogenation
Definition
step in the free radical reaction that starts with free radicals from the initiation phase yields free radicals
Term
termination phase of free radical halogenation
Definition
free radicals bonding to each other such that there are no free radicals left
Term
free radical initiators
Definition
they generate free radicals when heated

they usually have a weak bond (such as O-O) that readily undergoes homolytic cleavage
Term
methyl C
Definition
C wit 3 H attached; basically primary C
Term
methylene C
Definition
C with 2 H attached; basically secondary C
Term
methine C
Definition
C with 1 H attached; basically tertiary C
Term
quarternary C
Definition
C with 0 H attached; basically quartenary C
Term
how many lines to draw on the 13C spectrum
Definition
the number of unique C's plus symmetrical pairs
Term
when to make a line on the 13C spectrum short
Definition
when there's no H attached to it
Term
the lines to put to the left of 100 ppm on the 13C spectrum
Definition
the ones associated with the sp2 hybridized C's
Term
the lines to put to the right of 100 ppm on the 13C spectrum
Definition
the ones associated with the sp3 hybridized C's
Term
rate law in electrophilic reactions
Definition
rate = k [alkene][electrophile]
Term
Hammond's postulate basically says...
Definition
the transition state most closely resembles product or reactant, whichever is closest in energy to the transition state
Term
anything can move during a rearrangement, as long as...
Definition
it's moving towards more stable carbocation
Term
going from less stable to more stable is (endothermic or exothermic)?
Definition
exothermic
Term
why one possible reactant might be a better option than other possible reactants for the same product
Definition
yielding single product
Term
where to put the sp3 C's attached to halogens on the 13C spectrum
Definition
between the 100 and the C's to the far right
Term
where to put the sp2 C's attached to O on the 13C spectrum
Definition
far left
Term
where to put the sp2 C's on the 13C spectrum
Definition
a little to the left of 100ppm
Term
the range of the 13C spectrum
Definition
0-200
Term
orientation of the 13C spectrum
Definition
200 on left, 0 on right, and 100 in middle
Term
meso compounds aka...
Definition
identical
Term
generic rate law for electrophilic addition
Definition
rate = k [alkene][electrophile]
Term
how C's in a chain can be electrophilic centers
Definition
if there's a partial positive charge on them due to dipole moment caused by polarity of what they're bonded with
Term
how bonds are broken in polar reactions
Definition
heterolytically (electron pair moves instead of single electron)
Term
where to put the sp C's in the 13C NMR spectrum
Definition
in the middle, straddling the 100ppm in the middle
Term
where to put the sp3 C's in the 13C NMR spectrum
Definition
far right
Term
phenyl group
Definition
[image]
Term
[image]
Definition
phenyl group
Term
the alkene expected to react faster in an electrophilic addition reaction based on Hammond's postulate
Definition
the one that yields a more stable carbocation
Term
can ring C double bonds isomerize?
Definition
no
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