Chapter 1,2,3--
ionic vs covalent bonds
sigma vs pi bonds
pauli exclusion - spin pairs
Hunds rule
hybridization
atomic orbitals form molecular orbitals -- same #
in and out
formal charge = group # - lone paire - 1/2 (bonding
e-)
resonance -- representations, e- move, not atoms ,
obey octet rule, dont have same
energy, hybrid
empirical formula -- simplest reduction to atoms
molecular - represent molecules
Arrhenius Acid - dissolves in H2O to give H3O+
Bronstead - Lowry Acid - H+ donor
Lewis Acid - electron pair acceptor
Acid strength increases w/ size, resonance, electronegativity,
more positive on C, more polar
Ka, pKa
single bonds - free rotar double
bond- 1 sigma 1 pi, rigid-no rotation
triple bond- 1 sigma 2 pi ->orthogonal, rigid
Isomers:
constitutional/structural - same formula, different
connectivity
geometric - same formula, same connectivity
organic oxidation - gain of O or loss of H
Hydrocarbon classes--
alkanes-- R, alkyl groups, saturated, made completely
of C & H, haloalkane RX
alkenes-- R, 1 unsaturation--been oxidized, double
bond, , C & H
alkynes-- R, 2 unsaturated, triple bond, C & H
Aromatics-- Ar, Aryl groups, contain benzene ring
Alcohols-- ROH, hydroxyl groups
Thiols-- RSH, flavoring agent in natural gas
Aldehydes-- R-C=OH, cabonyl groups
Ketones-- R-C=OR'
Acids-- R-COOH Acid Halide-- R-C=OX
Acid Anhydride R-C=O-O=O-R
Esters R-C=O-OR' Amides 1o
R-C=O-NR 2o R-C=O-NR2
Ethers-- R-O-R, polar, organic "water"
Amines-- 1o RNH2 2o R2NH 3o R3N
Nitriles -- RCN
Alkanes: simplest family of hydrocarbons (H,C) also
called paraffins, single bonds only
aliphatic, homologus - differ in
chain length by CH2, CnH2n+2
n- straight/normal
iso- isomer sec - secondary tert -
tertiary
methane, ethane, propane, butane, pentane, hexane,
heptane, octane, nonane, decane,
undecane, dodecane, tridecane, tetradecane, pentadecane,
eicosane, heneicosane,
triacontane (all compounds from 3 have cyclic forms)
primary C - attached to 1 C secondary
- 2 C tertiary 3C &nbbsp; quadrinary
to 4C
primary H - attached to primary C
secondary H to secondary C tertiary to tertiary
naming
newman & sawhorse
geminal- two substituents on same C
vicinal - on adjacent C
ring flip -- relative position doesnt change
rotational strain (tortional) - staggered, elipsed
atoms as far as possible called
"staggard' (more staggered, lower E)
atoms close together called "eclipse"
(more elipsed, higher energy)
steric hinderance - guache interactions
ring (angle) strain -
tighter bond strain - more explosive
increase A value == more likely to be equitorial in
cyclohexane
rotomers - rotation
Chapter 4:
mechanism - how a rxn goes
addition: A + B --> C
elimination C--> B + A
substitution:
A-B + C-D ---> A-C + B-D
rearrangement: A --> W
homolytic cleavage (evemly broken)
-- generates radicals
heterolytic cleaveage (not same)
-- creates ions
initiation stepts - generates radicals
propogation- two types --one makes
product & radical, other makes only radical
termination - gets rid of radical
kinetics - how fast a rxn goes (rate)
rate = k [A]x[B]y
zero order - [x] is irrelevant
1st- [x] -> [2x] rate goes up by factor of 2
second
order [x] -> [2x] rate foes up by factor of 4
thermodynamics - how hot a rxn goes (stability)
Keq = [products]/[reactants]
>1 => favors products, reaction to completion
deltaG = products - reactants
deltaGo = RT(ln Keq) = deltaHo - TdeltaSo
reaction profiles/diagrams
transition states - dont exist,
"imaginary" structures to represent smooth transition
intermediate - real structures,
high E, reactive species ("step wise" rxn)
Hammon Postulate - transition state looks
like nearest energy spieces--
"early"
transition state looks like sm, "late" looks like products
kH/kD measure of R-H bond break
to R-D(euterium) bond break, determines
rate determining
step
radicals- more reactive w/ e- donating,
e- donating makes feel smaller, withdraw-larger
opp e-
donating pushes into neg charge
Chapter 5 :
symmetry operator - makes one side same as other side
(ex. plane)
infiite axis - move around, but
cannot tell
chirality- look @ orientation of atoms in space
chiral- unique orientation in space
(of 4 things about C), non-superimposible mirror
images
(enantiomers)
chiral center (steriogenic center)
- C where chiral, rep by *
n= # *
2^n = # enantiomers
steriochemistry - study of chirality
achiral- has symmetry element
stereoctenters rotate plane polarized light- dextrorotatory
(right), levorotatory (left)
angle specific rotation [alpha]D
= (observed rotation-degrees)/(path length x [x])
absolute configuration - does # go round to right
or left? - rank by atomic #, in case of tie,
move 1 atom out, multiple bonds
as "back bonded"
R(ectus)- # go around to right
S(inister)- # go around to left
Cohn-Ingold-Prelog (CIP) -- rules to generate priority
1.) higher atomic # is hgher priority
2.) if cant decide, move 1 atom out
3.) multiple bonds count as "back bonded"
diastereomeres - 2 or more stereocenters
meso - rendered achiral by symmetry element
racemic- mixture of R & S (50-50), called racemates
enantiomeric excess - how much more of one enantiomer
over 50% (60:40 => 20%)
resolution- separate mixtures (diasteriomers)
resolving agent- chiral molecule,
easily added/cleaved, making diastereomers, leave
resolving
agent to get enantiomers) ~~~ chiral chromatography
Fisher projections -- can only rotate 180degrees for
same molec, 90degrees=enantiomer
*Nitrogen sometimes not chiral because of inversion--lone
pair flips*
*can have chiral w/o chiral center* (ex. allene, fish
molecules)
chiral centers in mechanisms:
1. walden inversion R-->S, S-->R
2. racemization (inversion and retention, 100% R---->
50%R + 50%S)
3. retention (R--->R)
Chapter 6:
alkyl- fluro-
chloro- bromo- iodo-
type: primary, seconday, tertiary, vinyl, allyl, aryl
usage: solvent, coatings (teflon), refridgeration
(CFCs), anesthetics, pesticides
properties: dipole moments decrease going down except
Cl > F , bp increases w/size
bond length increases w/size, inductive
effect- all halogens are e- withdrawing
preparation:
substitution: free radical halogenation,
allylic halogentation
additions
converstions
REACTION MECHANISMS:
SN2 Bimolecular Nucleophilic Substitution
-inversion -concerted--transition
state -second order kinetics rate=k[Nu][SM]
-Dunnitz 109.5 degrees, nucleophile
must enter from backside at this angle
-steric hinderance, increase E
of transition state (inc deltaG, dec rate)
CH3X >
primary> secondary> tertiary
- nucleophile more reactive/inc
E => inc reaction rate by lower deltaG, stable, not basic
neg charge
better than nuetral, nuc strength inc left to right & down periodic
table
-leaving group- "soft" (big), stable,
lower transition state E
OTs > OFs>
I- > Br- > Cl- > F- >> OH- > NHR - >> OR-
-solvent - polar (to stabilize
transition state), aprotic (no protons), ex. THF, ethers
SN1 Unimolecular Nucleophilic Substitution
-retention & inverstion, loss
of optical activity
-true intermediate
- 1st order kinetics
rate = k [SM]
-intermediate (carbocation) CH3X
< primary < secondary < tertiary
-nucleophile - same as SN2, non
basic, more reactive (dec deltaG)
-leaving group0 rt determining
step- leaving group bond break, more stable anion/LG
==> faster
reaction
-solvent- polar, inc dielectric
k, stabilize carbocation formation, protic
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kH/kD - which bond impt to rate dt step
C-H bond weaker than C-D bond => if deprotination
is RDS, then kD >1, observe E2)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Elimination Reactions - eject small molecule, cometes
w/SN2 & SN1
E2- Bimolecular elimination (Nu- more basic ==> more
E2 instead of SN2)
E1- Unimolecular elimination (competes w/ SN1)
no kH/kD
follow Zaitsev's Rule- in an elimination
rxn, most substituted product b/c substitution
increases
alkene stability
Chapters 7,8,9
Alkenes- every two H is one unsaturation, C are sp2,
pi bonds lie along sigma bond, flat
in space, 6 atoms lie in plane,
bond angle is 120 degrees, rigid, stability increases w/EDG
E/Z - E two high priority on opp side, Z- two high
priority on same side
Alkynes- linear geometry, lots of s-character, sp
hybridized, easy to deprotinate
regiospecific- pick one product over another
Markovnikov's Rule- when adding HZ to a double bond,
the H goes to side w/fewer R groups,
the Z goes to side w/ more R
Preperation of Alkenes-
elimination
Uses of Alkenes-
halogenations
halohydrin
alcohol formation
oxymercuration
special- Carbenes, Smmons-Smith,
hydrogenation
oxidation- glycol, epoxidation,
antidiol, oxidative cleavage- ozonolysis, KMnO4
polymerization- catonic, radical,
radical addition
Forming Alkynes
elimination
Usage Reactions-
halogenation
hydrobromation
methyl ketone
hydrogenation/reduction
oxidation rxn
carbon nucleophile/chain extension
Bredts Rule- ther are no bridge head double bonds
unless there are 8 members or more in a ring
Hoffman's Rule- with large base, may eliminate to
lease substituted double bond
Chapter 10 - Alcohols (ROH) & Thiols (RSH)
Nomenclature -ane +ol
# chain to give alcohol priority
find other substituents
Properties
hydrogen bond- increase b.p
dipole moments (polar protic solvents)
CH3OH + HCl -----> CH3OH2
+ Cl-
CH3O- Na+ alkoxide are strong
bases (deprotanated acid-like alcohol)
NMR: OH- disappears w/ D2O
IR: 3600 cm-1 OH (1050 cm-1
C-O)
MS: 31 + alpha to alcohol
Formation Reactions
syn diol
anti diol
A/M
M
Formation via Nucleophilic Addition:
Grignard
"C Nu- "
Formation Via Reduction:
Raney Ni goes after carbonyl
NaBH4 delivery of H-
Lithium Aluminum Hydride >reducing
agent than NaBH4
Thiol-- NaNH2 thioether
mechanism--
Nu- addition to carbonyl --- addition
elimination rxn
Chapter 11: Alcohol Usage
Oxidation Reactions-
Na2Cr2O7
PCC
Reduction Reactions-
TsCl / LAH
HCl or SOCl2/pry or PCl3/ Cl2
PBr/Br2 or HBr
Alcohol as Nu-
alkoxide
Whittig Rxn - ylide (betaine/oxaphosphine)