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49 Cards in this Set
- Front
- Back
Conformational Isomers
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Geometric Isomers
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If isomerism is at a double bond then molecule is achiral.
Examples: Chair, Boat, Twist |
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Configurational isomers where the isomerism is NOT at a double bond
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Results in optical isomers
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Diastereomers
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Optical Isomer with two or more stereorcenters. (R/S)
DIFF physical properties - b/c of different intermolecular forces SAME chemical properties |
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Enantiomers
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Optical isomer that is non-superimposable mirror image.
SAME chem properties SAME physical properties except for rotation of polarized light and some reactions |
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Conformational Isomers
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Same molecule, different orientation.
Staggered, Vs Eclipsed Staggered - gauche and anti IDENTICAL CHEM and PHYS properties |
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Structural (Constitutional) isomers
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Same molecular formula, different connectivity
DIFF chemical properties DIFF physical properties |
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Sn2 Reaction
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Occurs in 1 step (concerted), with a transition state
Rate is bi-molecular k[A][B] Polar AProtic Solvents Primary > Secondary > Tertiary because of STERIC hinderance Optically active / inverted products |
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Sn1
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Occurs in 2 steps (carbocation formation is RDS),
Rate is 1 step : k[A] tertiary > secondary > primary because of needed carbocation stability Racemic Products |
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Good leaving groups
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When does the R/S nature of a chiral molecule change in an Sn2 reaction
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If the incoming nucleophile has the same priority of the leaving group it will go from R-S or S-R
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Which reaction requires STRONG nucleophiles? Sn1 or Sn2
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Sn2 - It occurs in one step
Polar APROTIC solvent |
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Sn1 and E1 reactions often occur _____1_______ and ______2______ with each other under the same reaction conditions
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1) Simultaneously
2) Competitively |
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Is a strong base required for E1 reaction to occur?
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No, solvents (PROTIC) can act as the base
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are sterics a factor in E2 reactions?
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No. Also, E2 is strongly favored by bulky, strong bases (like LDA)
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Nomenclature Priority
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1) Carboxylic Acid -COOH
2) Ester -COOR 3) Acyl Halide -COX 4) Amide -CONHR 5) Nitrile -CN 6) Aldehyde 7) Ketone 8) Alcohol -OH 9) Thiol -SH 10) Amine 11) Alkene 12) Alkyne 13) Ether |
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Free radical halogenation steps
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1) initiation
2) propagation 3) termination |
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What are VINYL derivatives
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mono-substituted ethylenes
ex: Vinyl Chloride is C=C--Cl |
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What are ALLYL derivatives
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A propene with a substitution on the 3rd C
ex: Allyl Bromide is C=C--C--Br |
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Formaldehyde
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Acetaldehyde
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Formic Acid
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Acetic Acid
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Bond Angle
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SP3 - 109.5
SP2 - 120 SP - 180 |
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Huckels Rule for aromaticity
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Must be planar and the pi electrons must equal: 4n+2
Example: benzene has 3 double bonds of 2 pi electrons each --> 3x2=6 pi. 4(1)+2=6 |
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Activators
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Donate electron density to the aromatic compound adding another conjugated pi bond
Directs ORTHO and PARA EX: NH3 |
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Deactivators
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Withdraw electron density from conjugated system and take away form the conjugated pi system
Directs META EX: -COOH, -CCl3, -CF3... |
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Alcohols can be good leaving groups only if you do what
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Turn -OH into a good leaving group by:
1) Protonate it 2) Convert it to tosylate 3) Form an inorganic ester |
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What does PCC do?
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It is a mild oxidant. Will oxidize a primary alcohol into an aldehyde, but NOT all the way to a -COOH
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What are good oxidizing agents?
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Transition metals with lots of Oxygen
Na2Cr2O7, KMnO4, CrO3 |
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What are good ways to synthesize Aldehydes and Ketones?
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1) Oxidation of alcohols
2) Ozonolysis of alkenes 3) Friedel-Crafts acylation |
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Good reducing agents?
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turn aldehydes and ketones into alcohols
BEST - LAH, lithium aluminum hydroxide Good - Sodium Borohydride NaBH4 |
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FORM =
ACET = |
FORM = 1 carbon ex: formic acid
ACET = 2 carbon ex: acetic acid |
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Grignard Reagents
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Soap
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Decarboxylation
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Loss of CO2
Common to dicarboxylic acids and B-Ketoacids Happens through a 6 member ring intermediate |
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Friedel-Craft Acylation
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Activating ORTHO and PARA directors
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Deactivating ORTHO and PARA driectors
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Deactivating META directors
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What is an anhydride
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the condensation dimers of carboxylic acids.
C-CO-O-CO-C (like a double ketone with an oxygen in between) |
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Fischer Esterification
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amide --> primary amine with CO2 as a leaving group
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What does IR spectroscopy measure?
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vibrations, in bonds THAT HAVE A BOND DIPOLE!!
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Two key IR absorption wavenumbers (1/lambda)
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1) OH - 3,300 cm^-1 (broad)
2) C=O - 1,700 cm^-1 (sharp) |
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5 important H-NMR shifts to know
1) Alkyl 2) Alkene 3) Aldehyde 4) COOH 5) Aromatic |
1) 1-3 ppm
2) 4-7 ppm 3) 9-10 ppm 4) 10-12 ppm 5) 6.5-8.5 ppm |
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Index of H deficiency
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n = # Carbons
x = # Hydrogens Include Halogens as a H |
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UV spectroscopy
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If you see this the molecule has conjugated bonds. The more conjugated bonds the lower the energy of transition
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Mass Spectrometer
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tallest peak is the 100% abundance reference
Farthest right (M+) (largest M/Z) is the mass of the parent compound minus one electron Use M+ - the mass of a fragment to know the mass of the piece that broke off |
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What is used to reduce Nitro compounds to primary amines?
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Iron or Zinc in dilute HCl
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