Organic Chemistry ACS Final I
Terms in this set (50)
Molecules with the same formula, different connectivity
Isomeric molecules that have the same molecular formula and sequence of bonded atoms, but that differ only in the 3-D orientations of their atoms in space
One of two stereoisomers that are mirror images of each other and are NOT superposeable
Stereoisomers that are not enantiomers. Occurs when 2 or more stereoisomers of a compound have different configurations at one or more of the equivalent stereocenters and are NOT mirror images of one another.
An atom that has at least 3 different attachments
Takes highest priority when naming.
Carboxylic Acid and derivatives
a racemic mixture
When looking at a chair conformation, which is more stable, when there are more substituents in the axial positions or the equatorial?
T/F For equal concentrations and equal path lengths, solutions of (+) and (-) enantiomers rotate plane-polarized light equally, but in opposite directions
T/F Compounds with R stereocenters rotate plane-polarized light clockwise
T/F Racemic mixtures can rotate plane-polarized light either clockwise or counter clockwise
T/F Meso compounds can rotate plane-polarized light either clockwise or counter clockwise
What is the stereochemical relationship between the salts formed by (+)-tartaric acid with racemic 1-phenylethanamine?
Cyclohexene reacts with bromine to yield 1,2-dibromocyclohexane. Molecules of this product would be
a racemic form and, in their most stable conformation they would both have bromine atoms equatorial.
a form of stereoisomerism describing the relative orientation of functional groups within a molecule
to be optically active a molecule must be
Are all molecules that are chiral optically active?
If the chiral molecules are in a racemic mixture (50/50) then no, it will not be optically active, however if any one steroisomer predominates, then yes it will be optically active.
A non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereocenters (chiral centers) it is not chiral. "Superposable" on its mirror image.
In these reactions, an electron pair on the negatively charged nucleophile attacks the carbon atom with a partial positive charge that is bound to an electronegative atom. The electronegative atom leaves as a leaving group
Two types of substitution reactions
SN1 (two steps)
SN2 (one step)
Nucleophilic substitution reactions that occur as a one step mechanism are called
SN2 stands for
substitution, nucleophilic, biomolecular
A two step mechanism involving initial ionization of the alkyl substrate to form a high energy carbocation, which then undergoes rapid reaction with the nucleophile are abbreviated
SN1 stands for
substitution, nucleophilic, unimolecular
what makes SN1 and SN2 outcomes distinctly different
the stereochemical outcomes are completely different
Unimolecular (SN1) reactions produce what kind of molecules?
SN1 reactions produce racemized tetrahedral stereocenters bearing the nucleophile because the intermediate carbocation is planar sp2 hybridized, and the nucleophile can attack from either side.
Bimolecular reactions (SN2) produce what kind of molecules?
SN2 reactions proceed by inversion of configuration at the carbon center
In these reactions, the proton is removed from the alkyl substrate as it becomes bound to the base, and the departure of both the proton and the electronegative "leaving group" yields an alkene.
What are the two types of elimination reactions
E1 (two steps)
E2 (one step)
What two factors determine whether the reaction will be substitution or elimination?
1. The primary, secondary, or tertiary character of the alkyl group bearing the leaving group
2. The nature of the base/nucleophile
If the leaving group is on a primary carbon...
If the leaving group is on a tertiary carbon
These types of reactions are faster on a primary carbon
These types of reactions are faster on tertiary carbons
Favor the elimination product from secondary and tertiary carbon atoms
Produce more substitution produce, mainly SN1
Weaker bases, such as alcohol and water
Favor elimination product, even from primary carbon atoms
The most common mechanistic step in all of organic chemistry
If we see a halide on a primary carbon, this indicates what type of reaction?
A halide on a tertiary carbon indicates what type of reaction
Which reacts faster in a substitution reaction, negatively charged nucleophile or neutral nucleophile
How is nucleophilic strength ordered
in the same order as base strength when the nucleophilic atoms are in the same period of the periodic table
Nucleophilic strength _______________ with increasing atomic size when the nucloephilic atoms are in the same column of the periodic table
As the periodic table goes down and left, the size of the atoms
as the periodic table goes up and right the electronegativity
Leaving group ability, increases with
decreasing base strength (i.e. on periodic table I is the weakest in the halide series, because HI is the strongest conjugate acid)
when looking at a molecule, and trying to figure out which has a stronger base, what could help us eliminate some options
ask if the molecule can be stabilized by resonance, if yes, these can be removed
if a sulfur atom is below an oxygen atom on the periodic table this means
the sulfur atom is larger and therefore more nucleophilic