1how many types of nucleophillic substitution are there
how many types of nucleophillic substitution are there
2Free Radical Halogenation
3What free radical is most is likely to be formed from bromination?
A tertiary radical (Most stable)
6What are nucleophiles?
Electron-rich species that are attracted to a positively polarized atom (i.e. a carbonyl carbon)
7What is a better nucleophile I or F?
Flourine
8What is a better leaving group I or F?
Iodine
10What doesn't a nucleophile play a role in the rate of an Sn1 reaction?
It is not involved in the rate-determining step...the formation of the carbocation.
11What factors will help carbocation formation and therefore increase the rate of an Sn1 reaction?
1. Highly substituted carbons.
2. Polar solvents (Surround and isolate the carbocation)
3. Good leaving groups (Weak bases)
13Why is a Sn2 reaction bimolecular?
Its rate-determining step is dependent on TWO species; both the substrate and the nucleophile.
14What are the best conditions for an Sn2 reaction?
You must have a strong nucleophile for the backside attack (thats what she said) with no steric hindrance.
15With respect to optical activity, what do your end products of Sn1 and Sn2 reactions become?
Sn1 = racemic mixture (nucleophile can attack from either the top or the bottom of the planar carbocation), therefore loss of optical activity.
Sn2 = inversion of configuration and remains optically active.
16What role does tosylate usually play in reactions?
It usually acts as a good leaving group and a good protecting group.
17Catalytic Hydrogenation
18Addition of HX to an alkene
19Addition of X2 to alkene
20Addition of H2O to alkene
21Free Radical Addtion to alkene
23Oxidation with KMnO4 (Cold)
24Oxidation with KMnO4 (Hot)
26Ozonolysis with Reduction
28What do you use to add to polymers?
29Whats another word for ethyne?
acetylene
30Synthesis of Alkyne starting from dihalide
31Synthesis of Alkyne using acytelide ion
33Alkyne Reduction by free radical
34Oxidation of Alkyne by KMnO4
36Hydroboration of Alkyne
37Key reaction mechanisms for Alcohols and Ethers
38Reduction to make Alcohol
40Alcohol dehydration (elimination)
41How do you make OH- a good leaving group for Sn1 and Sn2 reactions?
For Sn1 you can protonate it and make water the leaving group.
For Sn2 you can convert it to tosylate which is also a good leaving group.
42How do you convert an alcohol into an alkyl halide with an ester as an intermediate?
43What does PCC(pyridinium chlorochromate) do?
44What is jones reagent and what does it do?
it is CrO₃, H₂SO₄ in acetone and it oxidizes primary alcohols to carboxylic acids (STRONG!)
45Do ethers boil at high or low temperatures?
Low...no H-bonding.
46William Ether Synthesis
47How to Cleave an Ether!
48How can we go from Epoxide to Alcohol?
49How can you get ketones or aldehydes?
Oxidation of primary or secondary alcohols. Or ozonolysis of alkenes.
50What happens between Ketones and Enols?
51Basic attack of Nu on Carbonyl Carbon.
52How do you get an acetal or ketal?
When an aldehyde or ketone reacts with two equivalents of alcohol. A hemiketal or hemiacetal you get from one equivalent of alcohol.
53What is a cyanohydrin?
When al and ke react with HCN.
54Ammonia leading to condensation...
56What is a wittig reaction and what is its goal?
The goal is to make CARBON-CARBON double bonds by converting aldehydes and ketones into alkenes.
57What oxidizes an aldehyde and what do you get?
KMnO₄, CrO₃, Ag₂O, H₂O₂ and you get a carboxylic acid.
58What reduces aldehydes and ketones?
LAH or NaBH₄
59What are the reagents for Wolff-Kishner Reduction of al and ke?
H₂NNH₂, then a base and heat.
60What are the reagents for Clemmensen Reduction?
Hg(Zn) and HCl
61Why are carboxylic acids that much more acidic?
Resonance stabilization of between the alcoholic oxygen and the carbonyl oxygen.
62Electron withdrawing vs donating...what do each do to a negative charge and acidity?
Withdrawing delocalize/stabillize the negative charge (spread it over the molecule) which increases acidity. Donating does the opposite.
63What is significant about the α hydrogens on a β-dicarboxylic acid?
They are very acidic due to stabalization!
64Only primary alcohols can be oxidized to carboxylic acids. T/F?
True!
65How is carbonation of an orgmet reagent achieved?
66Is there a way to convert primary and secondary alkyl halides into carboxylic acids? Sure!!
nitrile formation followed by acid or base catalyzed hydrolysis.
67How do you form an ester with a carboxylic acid?
Addition of a primary alcohol under ACIDIC conditions.
68Acyl Halide from CarbAcid
69When might decarboxylation occur?
When carboxylic acids are heated, they may spontaneously loose a CO₂
70What is the order of reactivity for carboxylic acid derivatives?
Acyl halide > anhydrides > esters > amides
71How do you get an acyl halide from a carboxylic acid?
SOCl₂
72Friedel Crafts Acylation
Aromatic ring acylated through electrophillic aromatic substitution.
73Reduction of acyl halide?
H₂ Pd/BaSO₄ Quinoline
74What does acetic anydride look like?
75How can one make an anhydride?
React a carboxylic acid with a carboxylate salt or heat! to stabilize the carboxylic acid.
76The conversion of a carboxylic acid into ANYTHING depends on what?
The nucleophile!!
77When carbonyl's are attacked by hydrolysis, what does the nucleophile look like in acidic vs basic conditions?
Acidic: H₂O is attacking
Basic: OH- is attacking
In acidic conditions the carbonyl oxygen is protonated.
78How can you think of Lithium Aluminum Hydride?
It is like an H- nucleophile.
79Can nitrogen containing compounds form hydrogen bonds?
Yes, but the are not as strong as the hydrogen bond between H and oxygen! (Therefore lower boiling point).
80Can nitrogen-containing compounds be optically active?
Usually not because of nitrogen inversion but sometimes they can be isolated if the structure hinders inversion.
81How what is Gabriel Synthesis for?
Gabriel drank ammonia! OH NO!
82Amine from Nitro compound
83Amine from a Nitrile/Cyanide
86Hofmann elimination (not to be confused with hofmann rearrangement)/Exhaustive Methylation
87What is hofmann rearrangement?
An amide to a primary amine (Pg 389)
88What is a wash?
When you are using the extraction to remove impurities rather than separate out the desired product.
89Gravity filtration vs vacuum filtration
Gravity filtration is used when the desired product is in solution (usually hot) whereas vacuum filtration has the desired product being a solid.
90Why is temperature important in recrystallization?
The product needs to be soluble in high temps and insoluble in lower temperatures. IMPURITIES need to be soluble at all temperatures so that they stay in solution.
91When would distillation be favored over a separatory funnel?
When two liquids are miscible, the separatory funnel cannot be used therefore distillation is more ideal.
92When is vacuum filtration used?
ABOVE 150 C BOILING POINTS!
Vacuum will lower the pressure of the apparatus to ensure that the liquids do not decompensate under the extreme temperatures.
93Fractional distillation
Repeated distillations on inert objects like glass beads that help separate two liquids with boiling points less than 25 C apart.
94Thin-Layer Chromatography
Silica gel is polar!!
95Column Chromatography
Ion Exchange Chromatography
Size-Exclusion Chromatography
Affinity Chromatography
96In gas chromatography what is the eluant and what is the stationary phase?
The eluant or mobile phase is a gas (He or N) and the stationary phase is the temperature-regulated column.
Retention time: How long it took for each compound to travel through the column.
97How does isoelectric focusing work?
All proteins have an isoelectric point (no charge). When the molecule reaches the field that is equal to its isoelectric point, it will stop moving!
98How do Agrose gel and SDS-PAGE electrophoresis separate molecules?
Based on SIZE
99What is the purpose of Infrared (IR) spectroscopy?
Certain bonds absorb infrared light at different frequencies and this can then be measured through what is absorbed vs what is transmitted.
Used for FUNCTIONAL GROUP identification.
102The difference between oligo and polysaccharide?
Oligo is short poly is long.
103Where do you start numbering a carbohydrate?
On the carbonyl end.
104What are epimers?
Diastereomers that differ in the configuration of ONE carbon.
105Fischer to Haworth projection.
106What are anomers?
They differ only in the newly formed chiral carbon (after ring formation). Can be α vs β.
Glucose the α anomer is trans and the β anomer is cis (both pointing up!)
107Monosaccharide ester formation
All hydroxyl groups will be esterified!
108What happens in a Tollens' Test?
Testing for the presence of a reducing sugar.
Aldoses and ketose can be oxidized to carboxylic acids and therefore reduce Ag+ in the Tollens' test to metallic silver (Ag+ to Ag)
109What happens in a Benedict's test?
Testing for the presence of a reducing sugar.
Aldoses and ketose can be oxidized to carboxylic acids and therefore producing Cu₂O (red) from benedict's reagent (started with Cu(OH)₂
110How do you get glycosides from your hemiacetal monosaccharide?
Alcohol in the presence of ACID!!
111How do you get a disaccharide?
From the same reaction that gave us the glycoside! Its just that now the alcohol is.....ANOTHER MONOSACCHARIDE! YAY!
112What kind of bond does Cellulose have vs Starch and glycogen?
BETA 1, 4 vs the ALPHA of starch and glycogen (some α 1,6 in there too!)
113Basic structure of an Amino Acid
114What is the only amino acid that is NOT CHIRAL?
Glycine
115Naturally-occuring amino acids are L-enantiomers. T/F? Fischer projection?
True!! Fischer projections of amino acids have amino group to the left!
116What is a zwitterion and how does an amino acid look as such?
They are dipolar ions where each half neutralizes the other.
117Amino acids are amphoteric. Why?
They can act as an acid or a base. They have at least two dissociation constants (from H's on the n and c terminus)
118When does an amino acid take on the zwitterion form?
At the isoelectric point or isoelectric pH between pKa₁ and pKa₂
119Titration of Amino Acids (Glycine)
120What looses an H first in basic titration, the amino or carboxyl group?
The carboxyl group duh!
121Things to know about titration of amino acids...
1.Buffering capacity is greatest at the Ka's
2. Two moles of base need to be added in order to deprotonate one mole of most a.a.
3. When adding base, the carboxyl group looses the H first.
4. Titrations can be done in reverse starting with a basic solution and adding acid.
122Henderson-Hasselbalch Equation
145How many moles of acid are needed to neutralize 1 mole of a basic amino acid?
3 moles because of the extra R amino group.
146What is an amino acid called after it becomes a part of a peptide?
A residue.
147Why is rotation of the peptide bond limited?
There is resonance about the C-N bond giving it some double bond character.
148What level of structure is guided by hydrogen bonds for proteins?
Secondary structure resulting in α-helix and β-pleated sheets.
149What level of structure determines whether you have collagen or myoglobin?
Tertiary structure in that at this level you have the determination of fibrous vs globular proteins.
150What is a conjugated protein?
One that gets part of their function from a prosthetic group.
151What is zaitsev's rule?
When producing alkenes (usually from elimination reactions) there will be a major and minor product, the major one being the more subsituted and stable form.