HYPS Org
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- 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! -
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