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22 Cards in this Set
- Front
- Back
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physical properties of alkanes:
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as the chain grows (inc. in mlclr weight): BP and MP increase
but when branching occurs: decrease BP, increase MP |
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what's the density of alkanes like?
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lowest of about every cmpd
almost totally insoluble because it will float on water think oil spill on water |
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ring strain
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bending away from the normal 109.5 angle
=> crowding *cyclohexane has zero ring strain* ring strain increases as rings become larger or smaller at 10 carbons, ring strain again zero *less ring strain = lower energy = more stability* |
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H's projecting OUT from the chair =
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equatorial
H's projecting upward or downhard = axial when the ring reverses its conformation, all the H's reverse their conformation axials become equatorials, and vice versa |
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***crowding occurs often between axial groups***
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crowding = raising energy level = instability
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most-stable alkene =
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most-substituted alkene
elimination always makes alkenes |
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nucleophile
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agent that has extra electrons and wants to become neutral
more negative = better nucleophile more EN = worse nucleophile (takes electrons rather than donates them). thus, moving to the right and up DECREASES nucleophillicity |
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leaving group
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***the weaker the base, the better the leaving group***
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physical properties of alcohols
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as you increase molecular weight, BP and MP increase
as you branch, BP decreases - **BP and MP of alcohols is much higher than alkanes due to H-bonds** - **better solubility than alkanes for the same reason** |
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chemical properties of alcohol
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alcohols are less acidic than water
H2O > 1 alcohol > 2 > 3 |
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LiAlH4 is a stronger reducer than NaBH4
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will reduce aldehydes, ketones, esters, and acetates
while NaBH4 will only reduce aldehydes and ketones |
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***if an alcohol is a reactant, it will act as a nucleophile***
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alcohol = nucleophile
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oxidation:
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***loss of H2, addition of O, O2, X2***
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reduction:
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***gain of H2, loss of O, O2, X2***
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water is an excellent leaving group, as are
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weak bases
OH- is a BAD leaving group |
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generally, oxidizing agents will have lots of oxygen,
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and reducing agents will have plenty of H's
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when you see "ether",
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think "solvent"
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epoxides =
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far more reactive ethers
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ethers:
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non-reactive (excpet for epoxides)
**can H-bond with other compds, but not with itself** so low BP within itself |
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**when you see a carbonyl on the MCAT, think 2 things:**
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1. it's planar
- open space for attack 2. partial negative charge on the Oxygen, and thus partial positive on the carbon - negative on O means it's easily protonated - positive on C means it will be attacked by a nucleophile |
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naming for alcohols:
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the carbon with the alcohol must have the lowest number
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AlCl3 and BH3 are good Lewis acids
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they accept electrons
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