61 terms

chem 210 exam 2

chem 210 exam 2
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electrophiles
electron seeking reagents that have room to accept a electron pair
nucleophiles
reagents seeking a nucleus to which to donate a pair of electrons
proton transfer or protonation reaction
the transfer of a proton from one base to another
transition state
lying between the products and reactants
free energy of activation (delta G double dagger)
the height of the barrier, the energy that the reactants attain in reaching the the transition state
electrophilic reactions
lewis acid and base, strong acid-2 steps, weak acid- 3 step
electrophilic reaction strong acid
1)protonate
2) capture C+
regioselectivity
more stable of the C+ forms faster
C+ stability
1) resonance
2) 3degree> 2degree>1degree( how many c's bonded to
electrophilic reaction weak acid
1)protonate pi bond w/ actual acid
2)capture C+
3)deprotonate
conformations
different arrangements in space of the atoms of a molecule due to rotations around single bonds,energy differences dictated by noncovalent interactions
garche
60 degree in newman projection
anti
120 degree in newman projection
conformers
same connectivities but differ in spatial positions of atoms in relations to eachother
naming alcohols
change the ending e to ol, for two diol
stereoisomers
same connectivity and differ in the their atoms are oriented in space, same formula, same connectivity, different fixed geometry
configurational isomer
differ in the arrangement of their atoms in space and cannot be converted from one into another by rotations about single bonds
enantiomers
stereoisomers that are mirror images of one another, that are not superimposable
diastereomers
Stereoisomers that are not mirror images of each other. aka not enantiomers
optically active
chiral,
optically inactive
achiral
chiral
anything that cannot be superimposed on to its mirror image
achiral
anything that can be superimposed on to its mirror image
stereocenter
a tetrahedral atom that is bonded to four different substituents
racemic mixture
contains equal concentrations of 2 enantiomers and showes no optical rotation
absolute configuration
the actual orientation in space of the groups around a stereocenter
trans
2 substituents may be on opposite sides of the plane of a ring
cis
2 substituents may be on same sides of the plane of a ring
resolution of a racemic mixture
the separation of a mixture of enantiomers
resolving agent
the reagent used in the process of resolution of a racemic mixture
complexation/decomplexation reaction
nde+open shell <=> sigma
substitution reaction
sigma<=> sigma
a) bronsted base
b) at unhindered, sp3 C
addition reaction
pi->2 sigma
elimination reaction
2sigma-> pi
rate determining step
highest absolute E transition step
regioselectivity of rxn
the ration of products
if both carbon bond and reagent are unsymmetrical
then 2 outcomes possible
actual acid
H-A+H2O->H30(+)A(-)
eclipsing
an atom siting right in front of another(newman)
dehedreal angle
front to back (newman)
energies of interaction
e-/e- replusion
charge/charge(partial/partial)
h-bond donor/ accpter
steric/size hinderence
e-/e- replusion
all staggered form is better than eclipsed unless there is evidence,
steric size hinderence
repulsion of attached groups
abuses bending
charge/charge(partial/partial)
attractive/ replusive
h-bond donor/ accepter
attractive hydrogen bonding
small ring conformations
3-6 atoms
cyclobutane bends
butterfly up and down
cyclohexane bend
one end up, one end down
axial sites
straight up or down from hexane ring
equatorial sites
angle out parallel to c-c bond to sites away
more stable in ring
larger groups in equatorial sites
isomerism
different molecules, same formula, different connectivity=structural/ constitutional isomers
chirality
any system that creates handedness, create two and only two objects that have non-identical mirror image
case 1 stereoisomer
double bonds with different pairs of groups on each end
create two and only two stereoisomers, both achiral (E and Z)
case 2 stereoisomer
oppositely substituted even- sized rings
2 and only 2 stereoisomers, achiral (can't name, describe with cis and trans)
case 3 stereoisomer
tetrahedral stereocenter
2 and only 2 stereoisomers, both chiral(R and S)
1 stereocenter
2 stereoisomers (R,S) both chiral, enantiomers(R,S)
2 dissimilar stereocenter
create 4 stereoisomer, all chiral
2 similar stereocenter
3 stereoisomers,
2 chiral(SS&RR)
1 achiral(RS or SR)
meso
plane of symmetry, same constituents, opposite stereochem(R&S)
Structural ( constitutional) isomers
Same molecular formula different connectivity