OAT Organic Chemistry Review – Flashcards
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Nomenclature:
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-How many carbons? -1 =Meth. -2 =Eth. -3 =Prop. -4 =But. -5 =Pent. -6 =Hex. -7 =Hept. -8 =Oct. -9 =Non. -10 =Dec.
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Torsional Strain:
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-Electrons in bonds "push" away from each other.
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Steric Hindrance:
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-Functional groups interfere with each other.
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Staggered (anti):
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*Most favored conformation.
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Totally Eclipsed:
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*Least favored conformation.
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Chair Conformation:
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*Chair is more stable than boat.
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Axial vs. Equatorial:
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-A single substituted group will always prefer to be in the equatorial position.
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Axial vs. Equatorial (cont):
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-Between two substituents, the one with the larger electron cloud will be equatorial.
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Ring Strain:
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-Instability of a ring due to angle strain or conformational strain. *Ideal angle is 109.5 degrees.
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Fischer Projections:
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-Horizontal = out of the screen. -Vertical = into the screen.
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Chiral Carbon:
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-A central carbon bonded to four different things.
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Designating the Molecule as R or S:
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-(R) is clockwise. -(S) is counterclockwise.
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Optical Activity:
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-R and S chiral centers rotate passing light in opposite direction.
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Racemic Mixture:
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-A solution with equal amounts of two enantiomers has no net effect on rotating light. *NO net optical activity.
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Meso Compounds:
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-have an internal plane of symmetry so it does not have enantiomers. -No optical activity. -Considered achiral.
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Cis-Trans Isomers:
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-Cis are on the same side of the double bond. -Trans are on the opposite side of the bond.
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E-Z Isomers:
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-(Z) are on the same side of the double bond. -(E) are on the opposite side of the double bond.
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Nucleophile:
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-Loves positive charge. -Negative, or electron-rich.
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Electrophile:
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-Loves negative charge. -Positive, or electron-poor.
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Leaving Groups:
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-Carries negative charge with it, therefore stabilizing negative charge halogens (Cl-, Br-, I-).
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Substitution SN1:
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-1 stands for 1 thing only that matters: CARBOCATION. -SN1 stands for Unimolecular Nucelophilic Substitution. -Mechanism: Carbocation formation is rate determining step. -Kinetics: Rate = k[RX]. (1st order). -Substrates: 3 > 2 > 1 > CH3. -Nucleophiles: Does not require strong. -Leaving Groups: Good LG required (ex. Br-). -Solvents: POLAR PROTIC. -Stereochemistry: Not conserved.
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Substitution SN1:
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-Leaving Group leaves. New nucleophile comes in.
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Protic Solvent:
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-Able to form hydrogen bonds OR donate a proton. *Protic solvents form hydrogen bonds with the leaving group so it stays gone.
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Substitution SN2:
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-Bimolecular Nucleophilic Substitution. -Mechanism: Concerted backside attack. -Kinetics: Rate = k[RX][Nu].m (2nd Order). -Substrate: CH3 > 1 > 2. -Nucleophile: Strong Nu required. (Ex. NaOH). -Leaving Groups: Good LG required. -Solvent: Polar Aprotic.
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Substitution SN2:
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-Leaving Group refuses to leave. Nucleophile comes in and prevails over the LG, which leaves.
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Aprotic Solvent:
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-Unable to form hydrogen bonds, avoids H-bonding nucleophile.
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Elimination E1:
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-Elimination reaction creates a double bond. -First step of E1 and SN1 are the same. The second step is different. (Double bond formation for E1) (Substitution for SN1).
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Elimination E1:
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-Mechanism: Carbocation formation is rate determining step. -Kinetics: Rate = k[RX]. -Substrates: 3 > 2. -Bases: Does not require strong. -Leaving Groups: Good LG. -Solvent: Protic. -Stereochemistry = most substituted product favored. -Competition: E1 and SN1 happen at the same time, but E1 is favored by heat. -
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Elimination E2:
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-Mechanism: Concerted loss of H+ and LG. -Kinetics: Rate = k[RX][base]. (2nd order). -Substrates: 1, 2 or 3 but not CH3. -Bases: Strong base required. Large/bulky prevents SN2. -Leaving Groups: Good LG. -Solvents: aprotic is best. But the conjugate acid is used mostly. -Stereochemistry: Antiperiplanar. -SN2 and E2 occur together. SN2 inhibited with highly substituted substrates and bulky bases.
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what is a tie breaker for right to left?
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alphabet and most substitutes
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cyclo number
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least number and alphabet for tie
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sec-butyl
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4 carbon
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isobuyl
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y tail
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central carbon TEE
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tert-butyl
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cyclobutyl
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branch with a circle
