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45 Cards in this Set

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  • Back
Can charge molecules be aromatic?
Yes!
When it comes to charge stabiliziatoin, which is more powerful: resonance stabilization or inductive stabilization?
resonance stabilization
Aldehyde shows up where on the H NMR?
9.8ppm sharp
Addition of Amine to Carbonyl Group
Primary amine ==> Imine
Secondary amine ==> Enamine
(Note: tertiary and quaternary amines do not react with the C=0 group.)
E2 reaction will only occur with what conformation?
antiperiplanar conformation
What is the most straightforward method of making a benzoic acid from benzene?
- Place a methyl group and then oxidize the methyl group to the carboxylic acid...
- Can do this with AlBr3/CH3Br to get the methyl group on; and then oxidize with KMnO4
How do you make bromobenzene from benzene?
FeBr3/Br2
Reacting an alcohol with PCC will give you what?
a ketone
A ketone that reacts with a primary amine give an _____
imine
What is an imine?
a functional group or chemical compound containing a carbon-nitrogen double bond
(T/F) Whenever there is a double bond, there exists the possibility of having geometric isomers.
True
What happens when you react imines with lithium aluminum hydride (LAH)
create an amine... LiAlH4 is a reducing agent b/c there are a lot of H's attached to either B or Al.
If you obtain two products of unequal yield, what does this suggest?
that hte two products are diastereomers.
Whenever you see one molecule goign to form a ring, what should you suspect?
intramolecular reaction
What is faster: intramolecular or intermolecular reactions?
intramolecular reactions
If charged intermediates are involved in your mechanism, what should you make sure of?
that they go away before you get to the product, unless the product is chraged as well.
Claisen condensation
- Step1: At least one of the esters must possess an α-hydrogen atom as the first step of the reaction is deprotonation by the base to give an enolate ion
- Step2: The enolate then attacks the ester giving a β-Keto ester.
- Used when have an ester.
- Can use NaOMe/MeOH
What should you tihnk of whenever a question gives you the pKa of the substance being purified?
ion exchange chromatography or isoelectric focusing.
How do you determine the isoelectric points of a sample IN THE CASE OF INDIVIDUAL AMINO ACIDS?
In the case of individual amino acids, the isoelectric points can be determiend easily by taking the avg of the two closest pKa values.
Amino acids will be ______ charged at pH values below thier pI and ______ charged above their pI.
positively; negatively
How do you determine the isoelectric points of a sample IN THE CASE OF A PROTEIN when you have the individual pI of the amino acids?
FIND ANOTHER METHOD.
*** DO NOT TAKE THE AVERAGE OF THE pI OF THE INDIVIDUAL AMINO ACIDS!
What should you tihnk of whenever a question gives you the pKa of the substance being purified?
ion exchange chromatography or isoelectric focusing.
How do you determine the isoelectric points of a sample IN THE CASE OF INDIVIDUAL AMINO ACIDS?
In the case of individual amino acids, the isoelectric points can be determiend easily by taking the avg of the two closest pKa values.
Amino acids will be ______ charged at pH values below thier pI and ______ charged above their pI.
positively; negatively
How do you determine the isoelectric points of a sample IN THE CASE OF A PROTEIN when you have the individual pI of the amino acids?
FIND ANOTHER METHOD.
*** DO NOT TAKE THE AVERAGE OF THE pI OF THE INDIVIDUAL AMINO ACIDS!
ANILINE
is this an organic/inorganic/base/acid?
organic compound and weak base
acetophenone / methyl phenyl ketone
- properties?
hydrophobic since none of functional groups are capable of making hydrogen bonds.
phenol
organic/inorganic/basic/acidic
organic and weak acid.
Is the organic phase always on top of the aqueous layer during an extraction?
no. It depends on the density!
During extraction, how do you transpose a compound that is acidic or basic to the aqueous phase?
add base or acid, respectively.
Nitrile
~2200 cm^-1 indicates presence of a triple bond
(alkyne or nitrile)
what is an anion exchanger?
something that attracts anions and thus must have a positive charged group.
What can column chromatography be used for?
to separate substances based on size or charge.
How does an eluent for a column chromatography work?
- they must be eluted based on their affinities for the stationary phase. For this purpose, NaCl is added in an increasing concentration gradient.
- the least negatively charged proteins will emerge from the column before the proteins with the greatest negative charge.
All forms of chromatography have two ____
phases: a stationary phase and a mobile phase.
- separations of compounds take advantage of the different affinities that compounds have for the two different phases.
What should you watch out for when dealgin with chromatography?
Be cautious not to assume that the desired product will attach to the stationary phase. You may be presented with a sitaution in whcih purification will be better accomplished if the desired product has a higher affinity for the mobile phase.
For NMR spectrum, the number of signals you see tells you a lot about what?
the symmetry ==> the fewer signals there are, the higher symmetry the molecule possesses.
If get a sibnglet, this signifies what?
that there are no protons on adjacent carbons.
IR stretch at 1740 cm^-1 indicates?
presence of carbonyl.
IR stretch at 2220 cm^-1 indcates?
presence of a triple bond (either an alkyne or a nitrile)
In order fora substance to have a carboxylic acid, it must have what kind of IR stretch.
Alcohol
If a stretch is closer to 1740 than to 1700, it is probably ____
an ester
If the stretch is closer to 1700 than to 1740, it is probably a _____
ketone
If a molecule has four or more sites of unsaturation, what should you immediately suspect?
aromatic ring is present
Sites of Unsaturation equation
(2C + 2 -H)/2