organic chemistry chapter 18, Organic Chemistry 2, 2nd Exam, Reaction mechanisms 3- carboxylic acid derivates, Organic Chemistry Reactions & Mechanisms, Organic Chemistry 2 mechanisms, MCAT Organic Chemistry: Alcohols, reaction of Alkenes, Aromatic R...
Pyridium Chlorochromate (PCC)
** stops at an aldehyde due to lack of H2O PCC is an inorganic solvent turns alcohol into aldehyde (double bond O and an H )
Acid Catalyzed Dehydration Alcohol---> alkene
**requires a strong acid H2SO4 in 180 degrees c.(heat) OH is removed and double bond forms zaitsevs rule (more sub carbon get double bond)
oxymercuration reaction: what is the electrophile
+Hg(OAC) adds to the pi bond
Mechanism of hydroboration
-Borans adds to the double bond in a single step -boron adds to the less subsititued carbon -this orientation places the partial positive charge in the transition state on the more highly subsititued carbon atom
acid-catalyzed opening of epoxides in alcohol: what is the nucleophile?
-alchohol and it attacks and opens the epoxide
Synthesis of epoxides: is carried out in what type of environment and why?
-in an aprotic acid to prevent the opening of the epoxide
formation of halogydrin: what drives the opening of a halonium ion?
-its electrophilic nature -the weak nucleophile attacks the carbon bearing more positive charge
How does oxymercuration-Demercuration differ from hydration?
-milder conditions -no rearrangements or polymerization
LiAlH4
-reduce aldehydes, ketones, esters, and carboxylic acids to alcohols, and amides and nitriles to amines -will also open epoxides
base-catalyzed opening of epoxides: what is obtained after protonation
-the diol is obtained after protonation of the alkoxide with water
stereochemsitry of hydroboration
-the hydroboration step adds the hydrogen and the boron to the same side of the double bond (syn addition) -when boron is oxidized, the OH will keep the same stereochemcial orientation
Pinacol Rearrangement
1,2 diols 1.ketone 2. rearranged product
What 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)
1. NaNO2, HCl 2. H3PO2
1. converts PhNH2 --> PhN2 (aniline --> aryldiazonium salt) 2. converts PhN2 —> Ph
oxymercuration reaction: what is the reagent? what does it do?
1. mercury (II) -it dissociates slightly to form +Hg(OAc)
the double bond acts as a_____ attacking_________species
1. nucelophile 2.attacking electrophilic species
mechanism for nucleophilic addition in basic medium
1. nucleophile attacks carbonyl 2. proton transfer 3. enantiomers
mechanism for nucleophilic addition in acidic medium
1. proton transfer (carbocation) 2. nucleophile adds 3. water attacks hydrogen 4. enantiomers
Addition-Elimination Mechanism
1. ring must contain very strong deactivating group (EWG - ex. NO2) 2. LG = ex. X (halogen) 3. rxn is only possible if deactivating group is ortho or para to LG
Things 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.
What are the steps for hydration
1.Protonation of the double bond forms a carbocation 2.Nucleophilic attack of water 3.Deprotonation of the alcohol
how does demercuration differ form oxymercuration?
1.The NaBH4 replaces the mercuric acetate
How many moles of alkene can react with each mole of BH3
3 moles
How many moles of acid are needed to neutralize 1 mole of a basic amino acid?
3 moles because of the extra R amino group.
What is an amino acid called after it becomes a part of a peptide?
A residue.
Chlorination of benzene
A similar reaction as bromination of benzene occurs when chlorine is used rather than bromine.
What free radical is most is likely to be formed from bromination?
A tertiary radical (Most stable)
When 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.
Deprotection
Acetals/Ketals will not be oxidized by LiAlH4 & can be reverted back to carbonyl with an aqueous acid
When 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.
What is the order of reactivity for carboxylic acid derivatives?
Acyl halide > anhydrides > esters > amides
Bromine test for unsaturation
Add Br2 in CCl4 (dark,red-brown color) to an alkene 1.If the color changes then the bromine was added to the double bond 2.If there is no double there color changes
How do you form an ester with a carboxylic acid?
Addition of a primary alcohol under ACIDIC conditions.
Friedel-Crafts Alkylation
After formation of the carbocation, two steps are involved in this electrophilic aromatic substitution. In the first step, the aromatic ring functions as a nucleophile and attacks the carbocation, forming a sigma complex. The sigma complex is then deprotonated to restore aromaticity.
How do you get glycosides from your hemiacetal monosaccharide?
Alcohol in the presence of ACID!!
-OH as a protecting group
Alcohols can be used protecting groups for other functional groups such as aldehydes and ketones React an aldehyde with 2 equivalents of an alcohol (or a diol) to form an acetal (primary carbon with two -OR groups) React a ketone with 2 equivalents of an alcohol (or a diol) to form a ketal (secondary carbon with two -OR groups)
Monosaccharide ester formation
All hydroxyl groups will be esterified!
How 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!
Mesyl and Tosyl groups
Also serve as protecting groups (prevent reactions with -OH on a molecule) when reacted with an oxidizing agent
_____________ ____________ ______ is another common Lewis acid that can serve as a suitable alternative to FeBr3 for the bromination of benzene
Aluminum tribromide (AlBr3)
What is hofmann rearrangement?
An amide to a primary amine (Pg 389)
Friedel Crafts Acylation
Aromatic ring acylated through electrophillic aromatic substitution.
When does an amino acid take on the zwitterion form?
At the isoelectric point or isoelectric pH between pKa₁ and pKa₂
Base Catalyzed Epoxide Opening -OCH3/HOCH3
Attacks least substituted
Acid Catalyzed Epoxide Opening H+/HOCH3
Attacks most substituted
Diborane
B2H6 is a dimer of borane and is in equilibrium with a small amount of BH3
What 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!)
How do Agrose gel and SDS-PAGE electrophoresis separate molecules?
Based on SIZE
Primary Alcohol to Carboxylic Acid
Bleach, Chromic Acid
Secondary alcohols Ketones
Bleach, Chromic Acid, PCC, DMP, Swern
pyridine with Br2, 300 degrees
Br adds
pyridine with Br2, CH3COOH, 20 degrees, -HBr
Br adds
What 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.
pyridine with Cl2, -HCl
Cl adds
1 Alcohol to Cl substituent Br substituent
Cl: 1,2 SOCL2 3 HCL Br: 1,2 PBr3 3 HBr
Ubiquinone
Coenzyme Q; example of a biologically active Quinone (involved complexes I, II, III of ETC; lipid soluble because of longe alkyl chain) Ubiquinone is most oxidized form: can be reduced to Ubiquinol when it picks up electrons
Tosylates
Compound containing -SO3C6H4CH3 Derived from toluensulfonic acid
Mesylate
Compound containing -SO3CH3 Derived from methanesulfonic acid
Jones Oxidation
CrO3, H2SO4 + acetone Converts: primary alcohol --> carboxylic acid secondary alcohol --> ketone
Primary Alcohol to Aldehydes
DMP, PCC, Swern
What are epimers?
Diastereomers that differ in the configuration of ONE carbon.
What are nucleophiles?
Electron-rich species that are attracted to a positively polarized atom (i.e. a carbonyl carbon)
MCPBA
Epoxide ring forms from double bond
What is a better nucleophile I or F?
Flourine
How 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.
Quinones
Form by reacting a phenol with an oxidizing agent Named by indicating position of carbonyl numerically followed by quinone Ex. p-benzenediol (hydroquinone) + Na2Cr2O7, H2SO4 --> 1,4-benzoquinone (quinone) Resonance-stabilized electrophiles, most not aromatic (lack conjugated ring) Phylloquinone (Vitamin K1)
The _____________________ ___________, makes possible the installation of an alkyl group on an aromatic ring.
Friedel-Crafts alkylation
How do you get a disaccharide?
From the same reaction that gave us the glycoside! Its just that now the alcohol is.....ANOTHER MONOSACCHARIDE! YAY!
How what is Gabriel Synthesis for?
Gabriel drank ammonia! OH NO!
What is the only amino acid that is NOT CHIRAL?
Glycine
Gravity 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.
Mg, ether
Grignard reagent
Jones Reagent
H2CrO4 in H20, acetone primary alcohol---> acid (=O and OH) secondary alcohol---->ketone (=O) tertiary alcohol---> No reaction
what solutions does hydration of alkenes uses to drive equilibrium toward hydration?
H2SO4 or H3PO4
Alcohol--> haloalkanes
HX steps in and knocks off the alcohol (OH) group replacing it with a halide ( Cl,Br, and I) *F doesnt usually react *SN1 reactions will occur if tertiary *SN2 for primary
What are the reagents for Clemmensen Reduction?
Hg(Zn) and HCl
Catalytic Hydrogenation of Alkenes
Hydrogen(H2) can be added across the double in -only if a catalyst takes place (Pd,Pt or Ni catalyst)
Phenol
Hydroxyl groups attached to aromatic rings ~ Hydroxyl hydrogens of phenols are particularly acidic due to resonance within the phenol ring ~ Aromatic Alcohols
Quinones can be further oxidized to...
Hydroxyquinones
Reduction of acyl halide?
H₂ Pd/BaSO₄ Quinoline
What are the reagents for Wolff-Kishner Reduction of al and ke?
H₂NNH₂, then a base and heat.
Phylloquinone
Important example: used in photosynthesis and blood clotting
Bromination of Benzene
In the first step, the aromatic ring functions as a nucleophile and attacks the electrophilic agent, generating a positively charged intermediate called a sigma complex, or arenium ion, which is resonance stabilized. In the second step of the mechanism, the sigma complex is then deprotonated, thereby restoring aromaticity and regenerating the Lewis acid (FeBr3).
general mechanism for electrophilic aromatic substitution
In the first step,the aromatic ring functions as a nucleophile and attacks E+, forming an intermediate sigma complex In the second step, the sigma complex is deprotonated, restoring aromaticity
nitration of benzene
In the first step,the aromatic ring functions as a nucleophile, forming an intermediate sigma complex In the second step, the sigma complex is deprotonated, restoring aromaticity
sulfonation of benzene
In the first step,the aromatic ring functions as a nucleophile, forming an intermediate sigma complex In the second step, the sigma complex is deprotonated, restoring aromaticity The resulting anion is protonated
Aldol and E2
In what reactions is it important to have and alpha Hydrogen?
What is a better leaving group I or F?
Iodine
Column Chromatography
Ion Exchange Chromatography Size-Exclusion Chromatography Affinity Chromatography
How can you think of Lithium Aluminum Hydride?
It is like an H- nucleophile.
What 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.
What role does tosylate usually play in reactions?
It usually acts as a good leaving group and a good protecting group.
Why is a Sn2 reaction bimolecular?
Its rate-determining step is dependent on TWO species; both the substrate and the nucleophile.
Syn Hydroxylation of Alkenes: what 2 other reagents can you use instead of OsO4,H202?
KMnO4, -OH
What oxidizes an aldehyde and what do you get?
KMnO₄, CrO₃, Ag₂O, H₂O₂ and you get a carboxylic acid.
Secondary alcohols are oxidized to...
Ketones via PCC or any other stronger oxidizing agent
What reduces aldehydes and ketones?
LAH or NaBH₄
Do ethers boil at high or low temperatures?
Low...no H-bonding.
What is the most common used peroxyacid
MCPBA
formation of Halohydrin: What orientation does it have and what stereochemistry?
Markovnikov orientation anti sterochemistry
PCC is a...
Mild anhydrous oxidant
H2SO4
More substituted Alcohol from alkene
williams ether reaction
NaH reacts with 5 or 6 membered ring O- will react with the C before the halide kicking the halide off and forming a cyclo.
ROH react with thionyl bromide
OH is replaced by the Br SOBr2 in Pyridine or Triethyl amine (Et3N)
ROH react w/ thionyl chloride
OH is replaced by the Cl SOCl2 in Pyridine or Triethyl amine (Et3N)
The difference between oligo and polysaccharide?
Oligo is short poly is long.
Where do you start numbering a carbohydrate?
On the carbonyl end.
What is a conjugated protein?
One that gets part of their function from a prosthetic group.
NaBH4 "H+"
Only reacts with ketones (produce 2 alcohols) or aldehydes (produce 1 alcohols)
Syn Hydroxylation of Alkenes
OsO4, H2O2 - adds -OH to both sides of the double bond
How can you get ketones or aldehydes?
Oxidation of primary or secondary alcohols. Or ozonolysis of alkenes.
Primary alcohol w/ PBr3----> haloalkanes (Br)
PBr3 is attacked and loses a Br dibromophosphite is a good leaving group Br- that left the PBr3 attakcs the CH2 group to displace the dibromophosphite group
-OH is a...
Poor LG; needs to react to form a better LG (Mesylates and tosylates)
LiAlH4 "H+"
Produces 2 alcohol from ketone and 1 alcohol from aldehydes ethers and o-
ester
Product of carboxylic acid and alcohol in presence of acid
1,3-dicarbonyl compounds
Products of Claisen condensations
How can one make an anhydride?
React a carboxylic acid with a carboxylate salt or heat! to stabilize the carboxylic acid.
alcohol
Reagent needed for ester hydrolysis
Fractional distillation
Repeated distillations on inert objects like glass beads that help separate two liquids with boiling points less than 25 C apart.
Why are carboxylic acids that much more acidic?
Resonance stabilization of between the alcoholic oxygen and the carbonyl oxygen.
How do you get an acyl halide from a carboxylic acid?
SOCl₂
What level of structure is guided by hydrogen bonds for proteins?
Secondary structure resulting in α-helix and β-pleated sheets.
Hydroxyquinones
Share same ring and carbonyl backbone as quinones + addition of one or more -OH groups Naming: position of -OH groups is indicated by a number & total number of -OHs (if more than one) are indicated by a prefix (di-, tri-) with substituent name "hydroxy-" Contain EDGs which make them slightly less electrophilic Have biological activity (synthesis of meds)
Thin-Layer Chromatography
Silica gel is polar!!
With 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.
SOCl2, pyridine
Substitutes Cl for OH with inverted configuration. Cl is a good LG. Anti. Primary or secondary only.
SO3, H2SO4, heat
Sulfonation: ---SO3H
HgSO4, H2SO4, H2O
Terminal Alkyne -> Enol -> Ketone
What 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.
What 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
What 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)
What looses an H first in basic titration, the amino or carboxyl group?
The carboxyl group duh!
In 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.
What 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.
The conversion of a carboxylic acid into ANYTHING depends on what?
The nucleophile!!
Why 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.
Why is rotation of the peptide bond limited?
There is resonance about the C-N bond giving it some double bond character.
What is a zwitterion and how does an amino acid look as such?
They are dipolar ions where each half neutralizes the other.
What is significant about the α hydrogens on a β-dicarboxylic acid?
They are very acidic due to stabalization!
Amino 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)
What 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!)
Only primary alcohols can be oxidized to carboxylic acids. T/F?
True!
Naturally-occuring amino acids are L-enantiomers. T/F? Fischer projection?
True!! Fischer projections of amino acids have amino group to the left!
Can nitrogen-containing compounds be optically active?
Usually not because of nitrogen inversion but sometimes they can be isolated if the structure hinders inversion.
Menaquinones
Vitamin K2
resonance and hydrogen bonds
What makes enols more stable than ketones?
What is a cyanohydrin?
When al and ke react with HCN.
How 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.
When might decarboxylation occur?
When carboxylic acids are heated, they may spontaneously loose a CO₂
What 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.
When would distillation be favored over a separatory funnel?
When two liquids are miscible, the separatory funnel cannot be used therefore distillation is more ideal.
What is a wash?
When you are using the extraction to remove impurities rather than separate out the desired product.
Electron 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.
Can 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).
What 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.
ozonolysis: what is the intermediate
a five-membrered ring intermediate called molozonide -this rearranges to form ozonide
Whats another word for ethyne?
acetylene
Br2, FeBr3
add Br to aromatic ring (halogenation); can also use Cl2 and FeCl3; EAS
H2SO4, NaBr
add bromine (enantiomers)
HBr, H2O2
add bromine (enantiomers)
NBS
adds Br
when and why do we do methyl shift
after protonation to produce the more stable teritary carbocation
Alcohol -----> Sulfonate
alcohol reacts with p- Toluenesulfonyl chloride in pyridine hydrogen from alcohol is removed and forms HCl O attaches to the S of the p-tc
H2, Raney Nickel
aldehyde to alcohol
Alcohol with H2SO4/heat 180 Degree celsius -->
alkene
ROH with metals
alkoxide is formed OH turns to O^- and metal attatches
acid-catalyzed opening of epoxides in alcohol: what does this reaction produce and what type of stereochemistry
alkoxy alcohol with an anti stereochemistry
O3, H2O
alkyne to carboxylic acid
amide with dilute acid, heat H3O+
amide —> amine
NaNO2, HCl, CuBr
amine —> aniline —> bromine replaces N2+
the addition of water to a double bond forms..
an alcohol
What is the oritentation of oxidation of alcohol? how does it add?
anti-markovnikov
aromatic ring + CH3COCl —> 1.AlCl3 2.H2O
aromatic ring with CH3CO group (ketone group)
formation of halohydrin: where does the water add
back-side attack
why is the peroxide effect not seen with HCl and HI? but only with HBr
because the reaction of alkyl radical with HCl or HI is strongly endothermic
Why is there no rearrangements in oxymercuration-demecuration?
because there is no carbocation intermediate
Stereochemistry of halogen additon: why does the nucelophile attack from the back side?
because this assures an anti sterochemistry of addition
Tertiary alcohols
cannot be oxidized
Although an alkyl halide is by itself, electrophilic, it is not sufficiently electrophilic to react with benzene. However, in the presence of a Lewis acid, such as aluminum trichloride, the alkyl halide is converted into a ____________ which is an excellent electrophile and is capable of reacting with benzene in an electrophilic aromatic substitution reaction
carbocation
Zn(Hg), HCl, heat
carbonyl to alkane. these same reagents are also used to reduce NO2 to NH2 = Clemmensen Reduction
synt hydroxylation of alkene: what is formed after the osmate ester is hydrolyzed?
cis-glycol and regenerate the OsO4
Ozonolysis
cleaves double bond in half and produces aldehydes and ketons
What are peroxyacids used for?
converting alkenes to epoxides
peroxides produces..
free radicals
oxymercuration reaction: how does water approachs the merurinium ion
from the side opposite the ring (anti addition)
syn hydroxylation of alkene: what is the end product of using KMnO4 and OH instead?
glycol and a brown precipitate of maganese dioxide, MnO2
what happens if a halogen is added in the presence of water?
halohydrin is formed
formation of halohydrin: what is the intermediate
halonium ion (a "ring")
In the free radical initiation how do the peroxide bond break?
homolytically to form the first radical
aldehyde or ketone to diol
hydration by H2O (nucleophile) with acid or base
H2SO4/H2O heat, NH4OH
hydrolysis
HCN, H3O+
hydrolysis of CN to COOH
base-catalyzed opening of epoxides: what attacks and opens the ring?
hydroxide ion
how does alkoxymercuration-demercuration occur?
if the nucleophile is an alcohol, ROH, instead of water, an ETHER is produced
What is it about HBr that allows it to form the anti-markovnikov product?
it has the right reactivity for Each step of the free-radical chain reaction to take place
What is jones reagent and what does it do?
it is CrO₃, H₂SO₄ in acetone and it oxidizes primary alcohols to carboxylic acids (STRONG!)
oxymercuration reaction: what is the intermediate
it's a 3-membered ring called the mercurinium ion
tautomers
keto and enol forms are examples of
pyridine with CH3COCl, SnCl4,-HCl
ketone adds
How are the electrons held in pi bonds?
loosely
What types of reactions can you do with HBr?
markovnikov or anti markovnikov if Peroxide is present
oxymercuration reaction: follows what rule
markovnikov's rule
what type of rule does hydration of alkenes follow?
markovnikov's rule
Formation of halohydrins: what type of additon
markovonikov -the X will add to the less subsitiuted carbon
When benzene is treated with a mixture of nitric acid and sulfuric acid, a ____________ reaction occurs in which nitrobenzene is formed.
nitration
HNO3, H2SO4
nitration of benzene (NO2)
Is there a way to convert primary and secondary alkyl halides into carboxylic acids? Sure!!
nitrile formation followed by acid or base catalyzed hydrolysis.
pyridine with HNO3, (CH3CO)2O
nitro group adds
pyridine with KNO3
nitro group adds
The nitration of benzene can be used to install a ________ group on an aromatic ring. Once on the ring, the nitro group can be reduced to give an ________ group (NH2).
nitro, amino
so pyridine undergo friedel-crafts.?
no
are the carbocation intermediates found in all of these reactions?
no only some
is the bromine test for unsaturation, used to test the presence of a double bond?
no, Decolorizing bromine is the chemical test for the presence of double bond
ROH and acid
nucleophile in formation of acetal/ketal from ald/ket (and what catalyst?)
ROH
nucleophile in formation of hemiacetal/ketal from ald/ket
water
nucleophile in hydration of ald/ket
hydride
nucleophile in reduction of ald/ket
pyridine with NaNH2 (100 degrees)
nucleophilic substitution reaction: amine group adds
Catalytic hydrogenation: how are the hydrogen and alkene absorbed
on the metal surface
amide with Br2 no catalyst needed
one bromine adds
Syn hydroxylation of alkenes: what intermediate is formed?
osmate ester
KMnO4, NaOH, heat, H3O+
oxidation (add O)
O3, DMS
oxidative cleavage
Phenol Acidity
pKa ~10 (low pKa; most acidic alcohol) Phenols are much more acidic than non-aromatic alcohols they are resonance stabilized; they can form salts with inorganic bases such as NaOH **Strong acids: high Ka and low pKa
PCC, CH2Cl2
primary alcohol to aldehyde secondary alcohol to ketone (oxidation - adding O)
Swern Oxidation
primary alcohol to aldehyde secondary alcohol to ketone tertiary no reaction similar to PCC
Reactions of Phenols
proceed similarly to reactions with alcohol; hydrogen of -OH group is particularly acidic because of resonance-stabilization
electrophilic aromatic substitution
reaction in which one of the aromatic protons is replaced by an electrophile, and the aromatic ring is preserved.
Zn/HgCl, EtOH
reduce ketone or aldehyde to alkane but not strong enough to reduce CA
1. H3O+, H2NNH2 2. KOH, heat
reduces ketone to alkane
1. Fe or Sn, HCl 2. NaOH
reduction
R-CN with LiAlH4, H2O
reduction of CN to CH2NH2
NaBH4, MeOH
reduction: aldehydes or Ketone to alcohol
NaOCH3
replace LG with OCH3
10% NaOH 350 degrees
replace X with OH
The reaction between benzene and SO3 is highly sensitive to the concentrations of the reagents and is, therefore, ____________.
reversible
Explain the steps of addition of HX to alkenes
step 1:protonation of the double bond -this step forms the most stable carbocation step 2: nucleophile attacks the carbocaion, form an alkyl halid
What is the orientation and stereochemistry of halogen additon
sterochemistry: anti additon Orientation:
When benzene is treated with fuming sulfuric acid, a __________ reaction occurs and benzene- sulfonic acid is obtained.
sulfonation
Catalytic hydrogenation: what type of stereochemistry do they have?
syn stereochemistry since both hydrogen will add to the same side of the double bond
Sia2BH, H2O2, NaOH
terminal alkyne to aldehyde
base
the aldol reaction is catalysed by..
during halogen addition to alkenes, where does the second x- attack from
the back side
during halogen additon to alkenes, what type of intermediate does it form?
the intermediate is a 3-membrered ring called halonium ion
when bromine adds to the double bond what type of radical does it form
the most stable radical possible
enol and keto
the two structural isomers formed by aldehydes and ketones in solution
How do radical add to the a double bond? (to form what)
to give them the most stable radical in the intermediatw
In markovinkov's rule how does the proton add?
to the less subsituted end of the double, so the postive charge appears at the more subsitituted end (most stable carbocation)
During addition of halogens what does Cl2 and Br2,I2 add to the double bond to form? -What type of addition does it form
vicinal dihalide -this is an anti addition of halides
Formation of Halohydrins: what is the nucleophile?
water
acid
what catalyst in ester hydrolysis allows the reaction be be reversible?
a 1,3-dicarbonyl compound
what is ethyl acetoacetate an example of?
enol
what is more stable: the enol or keto form?
reaction between two esters
what is the Claisen condensation
the carboxylate anion is resonance stabilised
why is base-induced ester hydrolysis irreversible?
Primary Alcohols oxidized to....
~ Aldehydes via Pyridinium Chlorochromate (PCC) ~ Other oxidizing agents hydrate the alcohol and form carboxylic acid ex. Chromium(VI), Na2Cr2O7, K2Cr2O7
Alcohols are capable of...
~ Intermolecular hydrogen bonding ~ Higher MP and BP (more hydroxyls means higher MP/BP) and increased solubility in H2O
Naming
~ Replace "-e" with "-ol" ~ Common name: name alkyl as a derivative + alcohol (ex. ethyl alcohol) ~ Not highest priority: use prefix "hydroxy-"
Quinones
~ Treatment of phenols with OA ~ Indicate position of carbonyls numerically and ad quinone to parent phenol
