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mcat OC
Organic chemistry as by the aamc list
21
Organic Chemistry
Undergraduate 4
08/21/2009

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Cards

Term
name the 3 important hybrid orbitals and their respective geometries
Definition
sp-180* linear
sp2- 120* trigonal planar
sp3-109.5* tetrahedral, pyrimidal, or bent
Term
what is the difference between sigma and pi bonds?
which is more stable?
explain rigidity in molecular structure.
Definition
sigma bonds- strongest because the most stable. bind at plan of the atom's nuclei. free rotation about axis.

pi bonds- above of below the plane of the nuclei, less stable; more reactive, fixed rotation.
Term
what does vsepr stand for? be able to predict the shapes of molecules based on this.
Definition
valence shell electron pair repulsion.
AX- LINEAR
AX2- bent, etc
Term
Where are delocalized electrons located in resonance of ions and molecules?
Definition
pi orbitals
Term
what is imp to remember in drawing resonance structures?
Definition
electrons are moved, not atoms
Term
In regards to multiple bonding how does it effect bond length and strength.
Definition
bond length of c-c>c=c
bond strength of c-c same relationship exists with all bonds
Term
structural isomers aka ______
and define it.
Definition
constitutional isomers
same molecular formular difference in bonding of atoms
Term
define stereoisomers:
what are some examples of them?
Definition
same molecular formula and same bond to bond of atoms
diastereomers, enantiomers, cis and trans isomers, etc
Term
conformational isomers are?
how does one discern between the two?
Definition
not true isomers and have different spatial orientations. Distinguished via newman projections.
Term
polarized light is ___
what are the directions?
Definition
light going in the same direction.
[cw + d ]
[ccw - l]
cannot be determinied based on absolute or relative configuration
Term
what is the difference between absolute and relative configuration?
Definition
absolute configuration- determines the orientation of atoms about a chiral center. Lowest priority atoms are placed in the back or the direction is reversed.
R-CW....... S-CCW
relative configuration- inverted during SN2 reactions. molecules have the same orientation of atoms about a chiral center except for one substituent.
Term
what are racemic mixtures?
how does one separate enantiomers?
Definition
50% diastereomers 50% enantiomers. they don't rotate plane polarized light.
separation of enantiomers by resolution.
Term
Discuss the physical properties of alkanes
Definition
Increase Molecular Weight; increase boiling point and melting point. branching is unfavorable.
increase m.w with polar group attached decreases the solubility.
soluble in nonpolar substances.
low densities (oil floats on water)
Term
Important reactions of ALKANES:
(Radical reactions)
Discuss Combustion and Halogenation.
Definition
Combustion :
alkane + Oxygen gas -> CO2+H20 + heat.
Halogenation :
3 steps : initiation, propagation, termination.
stability: 3*>methyl
Term
how does ring strain affect cyclic compounds?
Definition
makes them more reactive since strain is unfavorable outside the cyclohexane circumstance.
Term
Look up nomenclature on alchols, alkanes, acids, etc
Definition
Term
what are some electron withdrawing groups?
Definition
-O
-OH
-N-R2
-OR
-R
Term
What are some electron donations groups?
Definition
anything with a partial + charge on the bonding atom. And halogens.
Term
Nucleophilicity:
if a nucleophile behaves as a base what happens?
what is the periodic trend for it?
it doesnt phase a (SN1/SN2) reaction.
Definition
elimination occurs
it decreases going up and to the right
SN1
Term
SN1 vs SN2
1) a strong nucleophile is required for?
2)How does steric effect affect SN1 and SN2 rxns.
3) polar solvents increase the rate of reaction of (SN1/SN2) reactions by? and does what to the other reaction.
4)the speed of an SN2 reaction depends on the ___ while an SN1 reaction depends on the ___.
5) what does each reaction do to the stereochemistry?
Definition
1)SN2 rxn
2) Sn1 secondary and tertiary subtrates- for a stale carbocation. while a sn2 reaction needs a less hindered substrate because of nucleophilic attack.
3) Increases sn1 reaction by stabilizing the carbocation, slows sn2 by stabilizing the nucleophile.
4) concentration of the substrate and nucleophile; concentration of the substrate.
5 SN1- racemic mixture with possible carbocation rearrangement, SN2- inversion of chiral center
Term
physical properties of ALCOHOLS
Definition
higher BP because of hydrogen bonding, and higher solubilities than alkanes.
tertiary alcohol more basic then primary alcohol.
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