Organic Chemistry ACS

find the longest continuous carbon atom chain contianing the carboxylic acid group
When naming carboxylic acids
What is the prefix in carboxylic acids?
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identify the alkyl group that is in the ‘alcohol’ portion of the molecule and name it; then identify the acid part of the molecule. The ester is named with the alkyl part first, and the acid part is named as a carboxylate.
To name an ester,
exact 2 subsituents
The terms ortho, meta, and para are used when benzene derivatives possess
More covalent bonds is more stable
Is a structure with more or less covalent bonds more stable?
Separation of charges cost energy and results in a less stable resonance contributor
What is the downside to separation of charges?
What does the nitrate ion look like lewis structure?
What does the nitrate ion look like lewis structure?
The bonding pi orbital is lower in energy than antibonding orbital (T/F)?
The sigma orbital is lower in energy than the pi orbital (T/F)?
How do you prepare epoxides?
Reagent is peracid (COOOH) ; alkene to an epoxide; maintain stereochemistry
How do you prepare epoxides?
What are the reagents of hydroboration of alkenes?
BH3, Et2O
What are the reagents of hydroboration of alkenes?
What is anti-markovnikov?
When the H adds to the carbon with the fewest attached hydrogens
What is anti-markovnikov?
H and B add to the same face of the alkene.
What is syn
Halide component of HX bonds adds to the more highly substitued carbon, whereas the hydrogen prefers the carbon which already contains more hydrogens.
What is markovnikov?
reagent is h2so4, heat or so3 (fuming h2so4)
What is aromatic sulfonation?
Ortho or para directing
What is an activating group?
meta directing
What is a deactivating group?
What are examples of activating EDG?
What are deactivating EWG?
EDG ______ the rate of reaction
EWG ________ the rate of reaction
Those that occur through the pi system and can be represented by resonance structures
What are resonance effects?
Those that occur through the sigma system due to electronegativeity type effects.
What are inductive effects?
Atoms adjacent to the pi system activate the aromatic ring by increasing the electron density on the ring through a resonance donating effect. (ortho-para directing)
What does EDG do?
EWGs with pi bonds to electronegative atoms adjacent to the pi system deactivate the aromatic ring by decreasing the electron density on the ring through a resonance withdrawing effect. (meta directing)
What does an EWG do?
inductive electron withdrawing and resonance donating (electronegativity and lone pair donation)
Halogens are deacitvaitng but have both
What is the aldol condensation reaction?
reaction in which an enol or an enolate ion reacts with a carbonyl compound to form a beta hydroxyaldehyde or b-hydroxyketone, followed by dehydration to give a conjugated enone.
What is the aldol condensation reaction?
Freely rotate the bonds (change the position of the OH and CH2OH in the fischer projection, then the oyxgen-H bond will nucleophilically attack the carbon, kick the double bond of the oxygen to the oxygen to form an oxygen anion and then get protonated by a hydrogen from the alcohol gorup used to nucleophilically attack the carbon. (mechanism is in notebook)
How does one transform a fischer projection into a cyclic ring in chair conformation?
Correy Fuches
What reaction uses BuLi?
ketone; alkene
What is the starting and end product of the Ph3P, Br- ?
A reducing agent; carboxylic acid and ester can be reduced by this in addtiiton to aldehydes or ketones
What is LiAlh4?
What happens in a free-radical additon of H-Br to alkenes? (HBr RO-OR)
antiadditon or syn addition of H and Br. Antimarkovnikov.
What happens in a free-radical additon of H-Br to alkenes? (HBr RO-OR)
NaOEt –> PhCh2Br –> H3O+, heat (Remove CO2)
Enolate (ester) –> ketone
is the alkaline hydrolysis of the fatty acid esters. Example: The chemical reaction between any fat and sodium hydroxide is a saponification reaction. triglyceride + sodium hydroxide (or potassium hydroxide) → glycerol + 3 soap molecules
Carbonyl attack
What is saponification?
an organometallic chemical reaction in which alkyl, vinyl, or aryl-magnesium halides (Grignard reagents) add to a carbonyl group in an aldehyde or ketone. This reaction is an important tool for the formation of carbon-carbon bonds.
What is a Grignard reagent?
Treat magnesium, and then you treat the Grignard with a strong acid. This gives you the alkane. You can also use this to introduce deuterium (D) into molecules! The first step is to make the Grignard reagent
How do you prepare a Grignard reagent?
shows no splitting at all; it consists of a set of single
peaks, one for each carbon or each set of equivalent carbons in a molecule. (EXAMPLE in the exam is that benzene is basically meso, so the signals must be individual 6 signals on their own.
What’s a decoupled HNMR?
What are the reagents of the Claisen condensation?
claisen condensation between esters containing alpha hydrogens, promoted by a base such as sodium thoxide, affords beta keto esters.
(use stronger bases to increase yield: NaH)
What are the reagents of the Claisen condensation?
Aldehydes and Ketones
The reducing agent: NaBH4 reduces?
Carboxylic acids and esters
The reducing agent: LiAlH4 reduces
Because the Al-H bond is weaker and thus less stable than B-H bond.
Why can LiAlH4 reduce more?
When using LiAlH4 to reduced amides what happens? (h2o workup)
How does one form an epoxide?
From C=C to epoxide ; ring closure forms via a intramolecular SN2 reaction.
How does one form an epoxide?
Cylic ether with a three atom ring; ring approximates an equilateral triangle ; making it pretty reactive, more than other ethers produced on a large scale.
What is the chemical properties of an epoxide?
mCPBA or a base
What reagents are used to form an epoxide?
Used in oxidation of primary alcohols to aldehydes; and oxidation of secondary alcohols to ketones ; usually used to oxidize alcohols into carbonyl compounsd
What is PCC in DCM?
Reaction which involves the reaction of an aldehyde or ketone; The phosphoran (PH3P= CR3R4 can be used to produce an alkene, but then proceed to form an unstable 4 membered ring.
What is the Wittig reaction?
Alkene CH2 is formed; PH3P=O by product.
What happens after phosphonium ylide is added to a ketone or aldehyde?
Forms into an epoxide!!
What happens when MCPBA is added to an alkene?
OH OH; BREAKS apart the ether
What happens when an workup is applied to an epoxide?
Good lewis acid catalyst
Why do we use AlCl3 in Friedel Crafts- Alkylation?
Wolff Kischner reduction; used to convert carbonyl functionalities into methylene groups; forms R,R=N-NH2 ; or just CH2!! The imine intermediate forms tho
What do the reagents KOH and hydrazine (NH2NH2) do?
What is the imine formation?
Benzene ring double bonded N-NH2
What is the imine formation?
What is the polymer Nylon 6,6 made from?
Polyamide ; 6 long carbonyl at each end of the chain; 4 carbons in between each of them; then 6 carbons in between each amine group
What is the polymer Nylon 6,6 made from?
What is the polymer polyurethane made from?
Alcohol , isocyanate, and ester like amide like thing. (RCOONHR)
What is the polymer polyurethane made from?
phenol group, formaldehyde
What is the polymer phenol-formaldehyde made form?
What is the polymer nylon 6 made from?
What is the polymer nylon 6 made from?
How is Dacron, a polymer made?
HOCH2CH2OH ; dicarboxylic acid with benzene in between total chain looks like O-CH2-CH2-O-COC6H4-CO
How is Dacron, a polymer made?
What does neopentane look like?
What does neopentane look like?
What does isopentane look like?
What does isopentane look like?
If there is a bulky group, where should it be placed on the chair conformation?
What does a cis cyclo molecule look like?
What does a cis cyclo molecule look like?
How to you calculate IHD?
How many stereoisomers per chiral center?
R,R, S,S
R,S, S,R
What are enantiomers?
R,S, R, R
What are diastereomers?
In cyclic systems a cis compound can react and become trans product
In cyclic systems a cis compound can react and become trans product
Form usually with least sterically hindered ‘H’ — makes least substituted Alkene
What happens in eliminated product when we use TBUOK?
Anticoplanar ~~
Because of steric hindrance, how must H’s be removed for elimination?
Sulfuric acid and phosphoric acid
What are the typical acids used in dehydration?
Temperature dependent on the structure of the alcohol.
What is the temperature used to dehydrate an alcohol to an alkene?
Primary alcohols
Which structures (primary, secondary, or tertiary) are the hardest to dehydrate?
two halogens bound to the same carbon atom
What are geminal dihalides?
Alkynes (pka 25, alakene pka = 44 , alkanes pka =50
Are alkanes, alkenes, or alkynes the most acidic?
NaNH2, in liquid NH3
Acetylenic hydrogens can be deprotonated with relatively strong bases (NaNH2)
What is sodium alkynide?
Alkyne with sodium ion attracted to the carbanion
What is sodium alkynide?
To nucelophilically attack a primary alkyl halide and form an alkyne with an acetyl group attached to it.
To eliminate a beta hydrogen from the primary alkyl halide to form a triple bond with a RC=-CH and an alkene
What is the purpose of sodium alkynide?
Hydrogen adds to alkenes in the presence of metal catalysts
How is hydrogenation of Alkenes carried out?
Insoluble platinum, palladium or Ni catalysts
What are the catalysts used in hydrogenation?
Rhodium or Ruthenium based; wilkinson’s catalyst Rh(C6H5)3P)3cL
What are the homogenous catalysts that can be used in hydrogenation?
Because an unsaturated compound becomes saturated with hydrogen compound
Why is hydrogenation called reduction?
Ni, Pd, Pt, Rh(C6H5)3PI3Cl
What are all the hydrogenating catalysts?
P-2 catalyst nickel boride (Ni(COOCh3)2) results in the syn addition of one equivalent of hydrogen to a triple bond; thus yielding a cis double bond.

reagent: H2/Ni2B(P-2)

What are the reagents for syn addition of hydrogen (to form cis-alkenes?)
Lindlar’s catalyst
What other catalyst can be used to produce a cis-alkene from an alkyne?
What are the reagents of lindlar's catalyst?
H2, Pd/CaCO3 ; quinoline
What are the reagents of lindlar’s catalyst?
What reagents can be used to synthesize trans-alkenes?
Dissolving metal reaction which uses lithium or sodium metal in low temperature (NH3 or NH2 solvent) produces trans alkenes

reagent: Li, C2H5NH2, -78 deg C, NH4Cl

What reagents can be used to synthesize trans-alkenes?
What is the reagent Li, C2H5NH2, -78 deg C, NH4CL used to form?
What does the vinylic anion prefer? Trans or cis
How does the vinylic anion look?
How does the vinylic anion look?
What does benzylic look like?
What does benzylic look like?
Is Oxygen counted into the IHD formula?
Does nitrogen count in the IHD formula?
What is the modern statement of Markovnikov's rule?
In the ionic addition of an unsymmetrical reagent to a double bond, the positive portion of the adding reagent attached itself to a carbon atom of a double bond so as to yield the more stable carbocaiton as an intermediate
What is the modern statement of Markovnikov’s rule?
When a reaction can potentially yield two or more constitutional isomers actually produces only one or a predominance of one isomer.
What is the regioselective reaction?
Get a chiral molecule, but racemic mixture (R/S) is produced becuase the carbocation is achiral (can attac with the nucleophile from both top and bottom)
What happens when you add HBr to butene?
form an alkyl hydrogen sulfate which is soluble in water; isopropyl hydrogen sulfate
What happens when cocnentated sulfuric acid is added to alkenes?
What happens when the isopropyl hydrogen sulfate is hydrolyzed by heating with water? Will form a 2-propanol and acid will be reformed
Will form 2-propanol
What happens when the isopropyl hydrogen sulfate is hydrolyzed by heating with water? Will form a 2-propanol and acid will be reformed
Form Markovnikov addition of water (markovnikov is adding the H to the Carbon with more H’s and add nucleophile to the carbon with less H’s
What happens when alkenes and dil. aq acids add together?
Addition of a small amount of acid and large amount of water
What is hydration favored by?
Concentrated acid with little water present
What is dehydration favored by?
What is oxymercuration-demercuration?
markovnikov; gives high yields of alcohols and avoids rearrangements;
What is oxymercuration-demercuration?
What is hydroboration-oxidation?
antimarkovnikov syn hydration; adds water to alkenes;
What is hydroboration-oxidation?
What are the reagents of Hydroboration oxidation?
BH3, THF, H2O2, OH-
What are the reagents of Hydroboration oxidation?
Hg(OAc)2, THF-H2O, NaBH4, OH-
What are the reagents of oxymercuration-demercuration?
Because the bulky boron group can approach the least sterically hindered carbon more easily.
– leads to anti-markovnikov product
Why does the boron become attached to the least substituted carbon of the double bond in hydroboration?
Acid-catalyzed hydrolysis: Markovnikov addition
Oxymercuration: Markovnikov addition
Hydroboration-oxidation: antimarkovnikov and syn addition
So what are the three alkene hydration methods (add water?)
Get vicinal dihalides; antiaddition; reaction is used as a test for alkenes because the red color of the bromine reagent disappears when an alkene or alkyne is present; allkanes don’t react with bromine in the dark

+Br2 –> room temperature, dark, CCl4 –> vicDibromide (colorless)

What happens when you add Br2/CCl4
SN2 attack on the bromonium ion intermediate; forms trans-1,2-dibromocyclopentane enantiomers
Why is the Br2/Ccl4 antiaddition?
Water acts as nucleophile to open the halonium ion; product is halohydrin C4H4X2
What happens when halogenation is carried out in aqueous solvent?
X2, H2O, alkene
What are the reagents of the halohydrin reaction?
What are carbenes?
Divalent but have neutral carbons with a lone pair of electrons; very reactive
What are carbenes?
How can methylene be created?
Heat or light intiated decomposition of diazomethane; react with alkene to form cyclopropane.
How can methylene be created?
What are carbenoids?
carbene-like species that reacts with alkenes
What are carbenoids?
syn addition; using reagents OSO4 or KMno4, the alkeen will form 1,2 -diols
What is syn 1,2-dihyrdoxylation?
Hot KMno4, OH-, H2O, heat, H3o+
These steps can be used as a chemical test for alkenes in which the purple color of the KMnO4 dissapears and forms brown MnO2, residue if alkene or alkyne is present.
What reagent is used to cleave alkenes?
What is ozonolysis of alkenes?
Cleavage of alkenes with ozone and workup with zinc in acetic acid leads to less highly oxidized carbons than products from cleavage with hot KMNO4.; unsubsituted carbons are oxidized to formaldehyde, mono=aldehydes, disub= ketones

reagents: o3, ch2cl2, -78 deg C, Zn/HOAc

What is ozonolysis of alkenes?
What happens when you add Br2 or Cl2 in tetrachloroform
trans product added to an alkene; if you want to go all the way –> for tetrabromoalkane or tetrachloroalkane. (2 halides per each carbon; but u have to increase the equivalents used.
What happens when you add Br2 or Cl2 in tetrachloroform
markovnikov and gem-halides; addition of hydrogen halides occurs once or twice depeding on molar equivalents

reagent (HBr)

How do we add hydrogen halides to alkynes?
What type of addition is Hbr?
What type of addition is Hbr?
use O3 and HOac or hot kmno4m Oh-, H3+
both forms 2 carboxylic acids
What is oxidative cleavage of alkynes?
What does high frequency (right of spectrum) mean?
What does low frequency (left of the spectrum) mean?
single unique set of protons
What each single peak correspond to on an NMR?
Signal of a given proton will be split by the effect of magnetic fields associated with protons on adjacent carbons (adjacent hydrogens +1 = peak)
How does signal splitting work?
What are the HNMR chemical shift ranges? (picture)
What are the HNMR chemical shift ranges? (picture)
– hydrogen atoms in the molecule feel different magnetic fields depending upon their location and the neighbor they directly attach to.
Why do Hydrogen atoms have different chemical shifts?
– nucleus feels weaker magnetic field; shielding is a barrier made of inner-shell electrons and it decreases the nucleus’ pull on the outer electrons
What is shielding?
– nucleus feels stronger magnetic field; deshielding is the opposite of shielding. When we say that an atom is deshielded, we mean that a nucleus whose chemical shift has been increased due to removal of electron density, magnetic induction, or other effects.
– essentially other atoms (more electronegative) are trying to pull the electrons away from the Hydrogens making the hydrogens more deshielded.
What is deshielding?
H-P; p=2.2, C=2.5
Which one is more shielded? H-P or H-C
F= 4.0
N= 3.0; Cl=3.0
I= 2.5; S=2.5; C= 2.5
What are the specific electronegativity values?
If replacment of each of the two hydrogens by some group leads to enantiomers, those hydrogens are enantiotopic **enantiotopic hydrogens have the same chemical shift and appear in the same signal.
– if replacement of each of the two hydrogens leads to diastereomers, the hydrogens are diastereotopic; diff shifts diff signals.
What are enantiotopic and diastereotopic hydrogen atoms?
Process of removing the coupling of H to an attached carbon is called BB (broadband) proton decoupling- most CNMR consisit of a single peak for each unique carbon
What is proton decoupling?
– depend on the electron density around the carbon nucleus
– decreased electron density causes the signal to move downfield (Deshielding)
– increased electron density causes the signal to move upfield (shielding)
What are the shifts in CNMR?
What does the CNMR spectrum look like? (picture)
carbon alkanes are off to the right; Cl,Br, ~20-60 ppm, OH is similar (40-60); alkyne is 80 ppm; benzene is (120-140 ppm), alkene is around (120-140) ; amide is 160 , carboxylic acid is around 170-180, ester is around 160-180) and ketone and aldehydes are 190- 220
What does the CNMR spectrum look like? (picture)
Removes all the info about the hbumber of hydrogens attached to each carbon; removes someof the coupling of carbons to hydrogens so that the coupled peaks will not overlap
What is off-resonance decoupled spectra?
What does mass spec measure?
Produces a spectrum of masses based on the structure of a molecule; a mass spectrum is a plot of the distribution of ion masses corresponding to the formula weight of a molecule and/or fragments derived from it;
– x axis represents the masses of ions produced
– y axis represents the relative abundance of each ion produced
– use fragmentation to impart the ions
-fragments are sorted accroding to their masses to charge ratio (m/z)
– most of the fragements detected have charge +1; the net effect is sorting of the ions by mass (m/z)
– alkyl substitued benzenes often lose a hydrogen or alkyl group to yield the relatively stable tropylium ion
– other substitued benzenes usually lose their substituents to yield a phenyl cation
What does mass spec measure?
loss of water
Alcohols usually show a M+ 18 peak from
Carbonyl compounds can undergo a mclafferty rearrangement
Carbonyl compounds can undergo a mclafferty rearrangement
How are radicals formed?
Homolytic bond cleavage –> radicals are highly reactive and short lived
– relatively weak bonds such as O-O, X-X can occur with the addition of energy in the form of heat or light
ex. dialkyl peroxide –> alkoxyl radicals
How are radicals formed?
What is hydrogen abstraction?
halogen radical can react to pair with its unshared electron
(alkane –> alkyl radical R)
What is hydrogen abstraction?
Atoms have higher energy (less stable) than the molecules they can form; the formation of covalent bonds is exothermic
– breaking covalent bonds requires energy (endothermic)
– homolytic bond dissociation is DH = positive)
Homolytic bon dissociation energies
Tertiary > secondary > primary > methyl
Radical stability ranking
alkanes undergo substitution reactions iwth halogens such as fluorine, bromine, and chlorine in the presence of heat or light ; forms hydrogen halide
How do alkanes react with halogens?
Just use halogens (usually most if not all will react) – but the some of the number of moles of each halogenated methane produced equals the number of moles of methane that reacted).

– methane +x2 –> heat or light –> tetrahalomethane

How can we radically halogenate all hydrogen atoms?
Use a large excess of methane – to make a monohalogenated produced and an excess of unreacted methane (large excess of alkane 🙂 )

methane + x2 –> heat or light –> halomethane

How can we control the amount of radically halogenated compounds that form
-Chlorine is relatively unselective and doesn’t greately distinguish between type of hydrogen –> leads to monochlorinated product (and more substituted product) +polychlorinated products +hcl
Chlorine as a halogenating reagent
What are the steps of radical reactions?
What are the steps of radical reactions?
chain initiation
What is the most endothermic-demanding process of the radical reaction?
fluorine > chlorine > bromine > iodine
What is the order of reactivity in methane substitution with halogens?
Fluorination has a low value for Eact for the first step and is extremely exothermic therefore fluorination reactions are explosive
Chlorination and bromination ahve increasinlgly higher values of Energy of activation and lower delta H values which makes these halogenation reactions less vigorous
Iodonination has a prohibitively high value for Eact of the first step and the reaction does not occur
Can you explain why fluorine and iodine are not used in radical formation?
Bromine is much less reactive but more selective than chlorine ** tertiary hydrogens are the best
What is the selectivity of bromine like?
Forms diastereomers (non superimposable ; chlorine attacks from the carbocations both sides (intermediate radical is chiral; and reactions on the two faces of the radical are not equally likely.
How to generate a second stereogenic carbon in radical halogenation
– antimarkovnikov addition; in the presence of ROOR (peroxide) give an anti-martkovnikov addition (br adds to the least substituted)
What is the reaction of afddition of hydrogen bromide to an alkene (in presence of peroxides)?
Markovnikov addition (bromo will add to the tertiary hydrogen; most substituted in the absensce of peroxides)
What is the reaction of addtion of hydrogen bromide to an alkene (without the presence of peroxides)?
Radical reaction
What process is used in polymerization?
What is the nomencalture of ethers
groups attached to the oxygen are listed in alphabetical order;
CH2OCH2CH3 is ethyl methyl ether
-ethers have an alkoxyl substituent on the main chain
– 2-methyoxypentane
– cyclic ethers can be named using the prefix ‘oxa’
Three membered ring ethers can be called exiranes
Four membered ring ethers can be called oxetanes
What is the nomencalture of ethers
How do you draw oxacyclopentane?
also known as tetrahydrofuran
How do you draw oxacyclopentane?
Alcohol; because they have capability of hydrogen bonding
-ether boiling points are roughly comparable to hydrocarbons of the same molecular weight
Which has higher boiling point: ether or alcohol?
Acid-catalyzed hydration of alkenes — reversible reaction with markovnikov regioselectivity –> alkene + HA –> C-C-H +A- forms an alcochol and a C-H
–>oxymercuration demercuration (
–> hydroboration-oxidation (antimarkovnikov, syn addition)
How do you synthesize alcohols from alkenes?
conjugate base is not well solvated so it is not as stable
Alcohols have similar acidities to water; sterically hindered alochols are less acidic
H2O > ROH> RC=-CH> H2>NH3 > RH
Why are alcohols stronger acids than terminal alkynes and primary or secondary amines?
1) Phosphorous tribromide (PBr3)
2) Thionyl chloride (SOCl2)
3) hydrogen halides (HBr)
We have to convert alcohols into alkyl halides because hydroxyl groups are poor leaving groups : there are three general methods that exist to convert alcohols into alkyl halides
SN1 mechanism for tertiary, secondary, and allylic and benzylic alcohols; these reactions are prone to carbocation rearrangments ; first oh group on the alkyl group is converted into a good leaving group –> then after it leaves a carbocation is formed –> halide (a good nucleophile) reacts with the carbocation
– primary and secondary chlorides can only be made with the assistance of a lewis acid such as zinc chloride
What is the mechanism of the reaction of alcohols with HX?
HI> HBr > HCl > HF
What are the orders of reactivity of alkyl halides from reaction of alochols with hydrogen halides?
primary and secondary
What type of alcohols do Pbr3 and socl2 react with in sn2?
The hydroxl group of an alcohol group can be converted into a good leaving group by conversion to a sulfonate ester (tosylates, mesylates, triflates)
base reacts with the S ; oxygen anion pushes electrons back down, cl leaves, then base takes the H to form the alkyl methanesulfonate
The hydroxl group of an alcohol group can be converted into a good leaving group by conversion to a sulfonate ester (tosylates, mesylates, triflates)
Why is tosylate a great LG?
Sulfonate ion (weak base) is a good LG
Why is tosylate a great LG?
How to form ethers?
1 alcohols can dehydrate into ethers ; use h2so4; temperatures may differ – high temp will cause elimination; 140 deg C is ok; 180 will cause elimination

base attacks acid, gets protonated H2O + good leavingr group, HSO4- is still present, then another molecule (alcohhol) has to act as the nucleophile and will cause the leaving group to leave. The alcohol now has the OH still but since there are two CH2CH3 and CH2CH3 at each end of the oxygen, the H must go to reduce the + charge on oxygen, then the h2o comes in to remove the H+ and form the ether.

How to form ethers?
What is the Williamson Ether synthesis?
How to synthesize unsymmetrical ethers ; sodium alkoxide attacks the alkyl halide, alkyl sulfonate, or dialkyl sulfate (shown in picture) – then the ether is formed ; along with Na+ L- (lg)

– typical substrates (unhindered with a good LG) are the following — 1 or 2nd alkyl halides, alkyl sulfonates, dialkyl sulfates
– L , – Br, -I, -OSO2R” or – OSO2R”

What is the Williamson Ether synthesis?
What is the way to synthesize ethers by alkoxymercuration-demercuration?
Alcohol is the nucleophile used in the analogous reaction to form alcohols from alkenes
What is the way to synthesize ethers by alkoxymercuration-demercuration?
– First formed using H2SO4 and CH2=C(Ch3)2 –> Protects the ether ; NaC=-CH (refer to ch 11 slide 17) ; forms a tert-butyl ether so that alkynes dont want to attack, or alkylation doesnt want to attck because of hindrance. can be removed using dilute acid (H3O+/H2O)
How can tert-butyl ethers by alkylation of alcohols be made as protecting groups?
How are silyl ethers used as protecting groups for alcohols?
TBDMS ether is common (tert-butyl dimethysiyl.
The protecting group is introduced by reaction of the alochol with chlorosilane in teh presence of an aromatic amine base such as imidazole or pyridine
– can be removed by treatment with fluoride ion (tetrabutyl ammonium fluoride)
How are silyl ethers used as protecting groups for alcohols?
generally unreactive,
– except for cleavage by very strong acids to form the corresponding alkyl halides (where they og came from)
-dialkyl ethers (CH3CH2-O-CH2CH3) undergo SN2 reaction to form 2 equivalents of the alkyl bromide

(ch3ch2-br +h2o)

ref to slide 19 – ch 11

What’s the reactivity of acyclic (linear) ethers?
What are epoxides?
3 membered ring cyclic ethers ; called oxiranes (tetrahydrofuran)
What are epoxides?
How are epoxides formed?
Formed by reaction of alkenes with peroxy acids (commonly used peroxy acid is MMPP – magnesium monoperoxyphthalate) ‘epoxidation’ and involves syn addition of oxygen ;

– Alkene + RCOOOH
– epoxide + Carboxylic acid

– epoxidation is stereospecific
– epoxidation of cis-2-butene- gives the meso cis oxirane, epoxidation of trans-2-butene gives the racemic trans oxirane


How are epoxides formed?
What about the reactivity of epoxides?
Considerably more reactive than ethers; this is because of their three-membered ring, which is highly strained ant therefore very reactive.

– an acid catalyzed opening of an epoxide occurs by intial protonatation of the epoxide oxygen, making the epoxide even more reactive (protonated epoxide), a weak electrophile will come in and cause the bond to break between one of the ether carbosn and the oxygen; this will form a protonated diol ; but the ultimate form will be O-C-O-C-O-H 1,2 diol + h3o+

– unsymmetrical epoxides, the nucleophile attacks primarily at the most substituted carbon of the epoxide (whichever has more carbons attached to it)

What about the reactivity of epoxides?
Nucleophile attacks at the least sterically hindere carbon of the epoxide (less CH3 AREA)
What happens in a base-catalyzed reaction with strong nucleophiles (alkoxide or hydroxide)?
Open the epoxide with water under acid catalyzed conditions gives the trans diol;

– to form the epoxide from an alkene and a peroxide (MMPP) –> epoxide ring; then will be treated with an acid (COOH); causes the bond of the O to break, then OH;OH on each one (TRANS TO ONE ANOTHER)

– a cis butene forms trans enantiomeric
– trans butene forms a meso butanediol. (this is when we form the diol)
previous when you form the epoxide, the cis forms the meso epoxide and the trans forms the enantiomeric epoxide

How does anti 1,2-dihydroxylation of alkenes via epoxides work?
sp2 hybridized and is trigonal planar (120)
What configuration is the carbonyl group?
Primary alcohols –> oxidized to aldehyde
Aldehyde –> reduced to primary alcohol
Carbonyl groups and alcohol groups can be interconverted by oxidation and reduction reactions
Turns into an aldehyde
What happens when we reduce a carboxylic acid?
Turns into alcohol
What happens when we reduce an aldehyde
What happens when we oxidize RCH3?
Formaldehyde (or aldehyde)
What happens when we oxidize alcohol
Carboxylic acid (highest oxidation state)
What happens when we oxidize aldehyde
1) COOH – carboxylic acid
2) RCOOR – ester
3) RCOH – alcohol
4) RCOR – ketone
What are the carbonyl compounds that can be reduced to alcohols?
primary alcohol
Using LiAlH4/et2o to reduce COOH forms what?
liAH or high pressure hydrogenation can accomplish this transformation
Esters are also reduced to primary alcohols
Aldehydes and ketones are reduced relatively easily; the mild reducing agent sodium borohydride (NaBH4) is typically used
LAH and hydrogenation with a metal catalyst can also be used
Aldehydes and ketones are reduced to 1o and 2o alcohols respectively
LiALH4 is very reactive with water and must use an anhydrous solvent such as ether ;
Nabh4 on the other hand ican be used in solvents such as water or an alcohol
Why do we have to use LiAlH4 in ET2O instead of a solvent like water?
PPC – pyridinium chlorochromate (made form chromium trioxide under acidic conditions) used in organic solvents such as CH2CL2
What reagent is used to oxidize primary alcohol to aldehyde?
KMnO4 ; in aq solution
What reagent is used ot oxidize a primary alcohol to a carboxylic acid?
H2CrO4 (chromic acid) and Jones reagent (CrO3 in acetone)
What reagent(s) are used to oxidize a secondary alcohol into a ketone?
Chromium oxide has a clear orange color which cahnges to a greenish opque if a oxidizable alochol is presnet
How to test for primary and secondary alochols
3200-3600 cm -1
Where are alcohols on the IR spectrum?
3.3 – 4.0
Where are alcohols in CNMR?
Where are the alcohols signals in CNMR?
Carbon-metal bonds varying widlely in character from mostly covalent to mostly ionic depending on the metal

– greater the ionic character, the more reactive the compound ; organopostassium compounds react explosively with water and burst into flame when exposed to air.

What are organometallic compounds?
R-X +2Li –> et2o –> RLi + LiX
How can organolithium compounds be prepared by reaction of an alkyl halide with lithium metal in an ether solvent?
Reacting organic halides with magnesium turnings; ether solvent is used because it forms a complex with the grignard reagent which stabilizes it

– RX +Mg –> Et2o –> RMgX
– ArX +Mg –> Et2O –> ArMgX

ex. Ch3I +Mg –> Et2o –> Ch3MgI
C6H5Br + Mg –> Et2o –> C6h5mgBr

How are grignard reagents prepared?
– organolithium and grignard reagents behave as if they were carbanions and they are threrfore very strong bases — react readily with hydrogen atoms attached to oxygen, nitrogen or sulfur in addition to other acidic hydrogens

–> form alkane (weaker acid) and alkoxide ion (weaker base)

Reactions of organolithium and organomagnesium
– useful nucleophiles for C-C bond synthesis
Organolithium and Grignard reagents can be used to form alkynides by acid-base reactions
Reaction results in ring opening and formation of an alcohol product; reaction occurs at the least-substituted ring carbon of the oxirane
How do grignard reagents react with carbonds of oxiranes?
Nucleophilic attack of carbonyl carbons is the most important reaction of grignard regeants;

– grignard’s with aldehydes and ketones yields a new carbon-carbon bond and an alcohol

– form alcohol, h2o, mgx2

What happens when grignard reagents react with carbonyl compounds?
primary alcohol (H3o+ used to supply the H)
Reaction of grignard’s with a formaldehyde yields a
secondary alcohol (h3o+ used to supply the H)
Reaction of grignard’s with a higher aldehyde yields a
tertiary alcohol (NH4Cl is used to supply the H
Reaction of grignards with a ketone yields a
– ketone formed by the first molar equivalent of Grignard’s reagent; reacts a second equivalent to produce the alcohol
– final product contains two identical groups at the alcohol carbon that are both derived from grignard’s

– 2 equivalents of grignards – along with an alcohol group and R’ (forms a 3 alcohol)

What happens when ester reacts with two molar equivalents of grignards ?
– The acidic hydrogens will react first and will quench the Grignard reagent;
– two equivalents of grignard reagent could be used so that that first
Why can’t the Grignard reagent not contain any acidic hydrogen atoms?
Attack aldehyde or ketone, form lithium alkoxide –> hydrolyse –> alcohol
Organolithium reagents tend to be more reactive
What are the uses of sodium alkynides
They react with carbonyl compounds such as aldehydes and ketones to form new carbon-carbon bonds
What are the uses of sodium alkynides
What is the reagent Lithium Dialkyl cuprates used for?
Corey-Posner, Whitesides-House synthesis ;
Alternative formation of carbon-carbon bonds which, couples two alkyl halides

-RX +R’X –> R-R’

Any alkyl halide –> RLi –> Cui –> R2CULi –> RX –> R-R’ +RCu +LiX

What is the reagent Lithium Dialkyl cuprates used for?
have a p orbital on a carbon adjacent to a double bond; p orbital can come from another double or triple bond ; the p orbital may be the empty p orbital of a carbocation or a p orbital with a single electron in it (radical)

-why are they good? — special stability to the molecule
– conjugated molecules can be detected using UV spectroscopy

What are conjugated unsaturated systems
Depends on reaction conditions; at low temperature the halogen adds across the double bond; at high temperature or at very low concentration of halogen, an allylic substitution occurs
CH2=CH-CH3 +X2 — low temp/CCl4 –> Ch2 -X – CH – X – CH3
CH2 = CH-CH3 +x2 — HIGH TEMPERTUARE OR low concentration of X2 –> CH2 = CH – CH2X +HX
When does Bromine and propene react?
High temperature in gas phase; reaction is a free radical chain reaction; in the initiation step a low concentration of chlorine radical is produced; int eh first proapgation step an allyl radical is formed , in the second propagation step the allyl radical reacts with moelcular chlorine
When can allylic chlorination be performed?
Why do allylic radicals form readily?
Because they are more stable than ordinary primary, secondary, tertiary, or vinyl radicals ; of all the dissociation energies, the allyl radical is the lowest, and the vinyl radical is the most.
Why do allylic radicals form readily?
allylic > 3 > 2 > 1 > vinyl
What is the relatively stabilty of some carbon radicals?
What is the radical reaction for adding bromine for allylic substitution?
Use NBS (N-bromosuccinimide) in the presence of light or peroxides (propene –> 3-bromopropene)

N-Bromosuccinimide converts into Succinimide.

What is the radical reaction for adding bromine for allylic substitution?
What are the propagtion step sof rallylic bromination with NBS?
– A bromine radical reacts with propene to produce an allylic radical and HBr
– HBr reacts with NBS to produce a bromine molecule (radical
– a molecule of bromine reacts with a propene radical to regenerate a bromine radical
What are the propagtion step sof rallylic bromination with NBS?
MO description; when an allylic hydrogen is abstracted to form an allyl radical, the developping p orbital on the sp2 carbon overlaps with the p orbitals of the alkene ; new p orbital is cojugated with the double bond p orbitals; the radical electron and the pi electrons of the alkene are delocaized over teh entire ceonjguated system; delocalziation –> increased stability.
– three p orbitals of the allylic system combine to form three molecular orbitals (bonding molecular orbitals contains two spin-paired electrons and this orbital increases bonding between the carbons
– the non bonding orbital contains a lone electron which is located at carbons 1 and 3 only.
What is the stability of the allyl radical?
What are two resonance forms of the allyl radicals?
What are two resonance forms of the allyl radicals?
Contain 2 double bonds
What are characteristic about alkadienes?
Conjugated dienes affect each other when they react, isolated doubel bounds react separtaely and do not affect each other; cumulated are just all in one row ; no separation between p orbital and s orbital.
What are cumulated, conjugated or isolated double bonds?
1.34, 1.47, 1.34 A; the central bond is shorter than that in ethene for two reasons – the signma bond between C2 and C3 is made from sp2-sp2 overlap
So what is the bond length difference in 1,3-butadiene?
s-cis and s-trans
s indicates that the conforamtions orginate from rotation around a single bond; s-trans is more stable because it is less sterically hindered.
What are the two planar conformations of 1,3-butadiene ?
The wavelength of radiation absorbed and the intensity of the absorption depend on the structure of the molecule
– the uv vis spectrum is typically measured from 200-800 nm
Why can we see conjugated compounds in the UV regions on the electromagnetic spectrum?
In UV-vis spectroscopy the electrons are excited from lower energy leve3ls to higher nes;
– the electron is generally excited from the highest occupied molecular orbital (HOMO) to the lowest unoccupied moelculcular orbital (LUMO)
– alkene and nonconjugated dienes ahve absorptions below 200 nm because the energy difference between the HOMO and LUMO is large
– in conjugated dienes, these energy levels are much closer together and the wavelengths of absorption are longer than 200 nm.
What is the absorption maxima for both nonconjugated and conjugated dienes?
the smaller the energy difference between the HOMO and LUMO;
The longer the conjugated system,
carbonyl compounds; unsahred electron on oxygen is promoted into the pi 3
What other compounds also absorb light in the UV region?
At room tmeperature (78%) additon 1,2; at n
What happens when 1,3-butadiene reacts with one equivalent of Hcl at room atmepreature -?
planar monocyclic rings with continuous system of p orbitals and 4n+2pi electrons are aromatic (n=0,1,2,3)
What is Huckel’s 4n+2pi electron rule?
Deriving the relative energies of orbitals of a system with a cyclic continuous array of p – orbitals; polygon corresponding to the ring is inscribed in a scircle with one point of the polygon pointing directyly down; horizonta line is draw where vertices of the polygn otoucht ehc circle — each line corresponds to the energy level of the MOs at those attooms; a dashed horizontal line halfway up the circle indicates the separation of bonding and antibonding orbitals.
What isdoes the polygon in a circle method used for?
What does cyclooctatetraene do because it has 2 unpaired antibonding orbital electrons?
adopts a nonplanar conformaiton with localized pi bonds to avoid instability
What does cyclooctatetraene do because it has 2 unpaired antibonding orbital electrons?
Monocyclic compounds with alternating double and single bonds;

named using a number in brackets that indicates the ring size
ex. benzene is [6] Annuelene and [8] annuelene is cyclooctatraene

What are annulenes?
– [14] annulene, [18] annuelene ; [16] annulene is NOT aromatic;
– [10] annuelen should be aromatic but none of them can be planar; angle strain, steric interaction or etc.
– cyclobutadiene is [4[ annuelen and is not an aromatic – it does not follow the 4n+2 rule and is highly unstable
Which annlenes are aromatic? (4n+2)
Provides regions of great shielding ; large annulenes tend to be highly shielded; protosn outside the ring appear at 9.3 (highly deshielded) whereas those on the inside of the ring tend to appear at -3.0 (highly shielded)
What’s great about ring current?
Because it becomes the aromatic cyclopentadienyl anion when a proton is removed; cyclopentadienyl anion has 6 pi electrons in a cyclic, continuous pi electron system ; thus it is aromatic
cycloheptatriene is not aromatic because its pi electrons are not declocalized around the ring
What makes a compound acidic?
Have two or more benzene rings fused together
ex. naphthalene, etc.
What are benzenoid aromatic compounds?
three resonance structures; show that 10 pi electrons of napthalene are delocalized and that it has substantial resonance energy; EXCEPTION: pyrene has 16 pi electrons; but is known to be aromatic; ignore the central double bond.
How can napthalene be represented?
What is characteristic about nonbenzenoid aromatic compounds?
Dont contain benzene rings, azulene has substance resonance energy and also substantial separation of charge
What is characteristic about nonbenzenoid aromatic compounds?
Bucky ball; C60 compound with interconnecting pentagons and hexagons; each carbon is sp2 hybridized and has bonds to 3 other carbons;
What are fullerenes?
Have an element other than carbon as the mmeber of the ring; ex. pyridine, pyrrole, furan, thiophene
– pyridine has an sp2 hybridized nitrogen; the porbital is part of the aromatic pi system of the ring; nitrogen lone pair is in a sp2 orbital orthogonal to the p orbitals;
– lone pair on nitrogen is avaliable to react with protons so pyridine is basic.
What are heterocyclic aromatic compounds?
C-H stretching occurs near 3030 cm-1; stretching motions of th ering give bands at 1450-1600 cm-1 and two bands near 1500-1600 cm-1;
What is the IR spectra of benzene derivatives?
moderate intensity near 205 nm, less intesnse band at 250-275 nm.
What is the UV spectra of aromatic benzene derivatives?
major ion in mass spectrum of alkyl benzenes is m/z 91; corresponds to C6H5Ch2+ which rearranges to a tropylium ion
What is the mass spectra of aromatic compounds
– Aromatic compounds under electrophilic aromatic substitution; aryl group is removed by removal of a hydrogen atom from an arene
What is electrophilic aromatic substitution?
x2, FEX3,
What is the reagent used to halogenate a benzene?
What reagents are used to nitrate a benzene?
SO3, H2SO4
What reagents are used to sulfonate benzene?
RCl2, AlCl3
What do reagents are used for friedel’s crafts alkylation (adding R group); R
acyl chloride and alcl3
What reagents are being used for friedel craft’s acylation?
– benzene reacts with an electrophile using two of its pi electrons; reacts further;
– forms a arenium ion; which is stabilized by resonance which deloca;zises the charge; step 2 proton is removed and the aromatic system is regenerated (this time with the added group / electrophile) as the new benzene.
What’s the mehcanism for electrophilic aromatic substituition?
How do we carry out the steps to halogenate a benzene?
– need lewis acid as a catalyst;
-Cl2 and Br2 are good halogenators;
-Flurination occurs so rapidly that its hard tos top at monofluorination of the ring
-iodine is so unreactive that an alternative method must be used

1. bromine reacts with ferric bromide to generate an electrophilic bromine species
2. highly electrophilic bromine reacts with pi electrons of the benzene ring; forming an arenium ion
3. proton is removed from the arenium ion and aromaticity is regenerated (Catalyst is regenerated)

How do we carry out the steps to halogenate a benzene?
Hno3 and h2so4 – form a nitronium ion ; this becomes the electrophile the benzene ring attacks.
How do we carry out the nitration of benzene?
How do we carry out the sulfonation of benzene?
Occurs most rapidly using fuming sulfuric acid (concentrated sulfuric acid that contains so3);
– so3 + is attacked, benzene sulfonate ion accepts a proton to become benzenesulfonic acid
– sulfonation is an equilibirium reaction, thus all steps involved are equilibrium;
– desulfonation can be accomplished using dilute sulfuric acid (high water conc) or passingsteam throught the reaction and collecting the volatile desulfonated compound as it distills with steam.
How do we carry out the sulfonation of benzene?
An aromatic ring can be alkylated by an alkyl halide in the presence of a lewis acid — serves to generate a carbocation electrophile
What is Friedel Crafts alkylation?
Using PCl5 or SOCl2 on carboxylic acid
How are acid chlorides made?
Powerful EWG; amino groups also make the ring less reactive to friedel crafts rxn because they come EWG upon lewis acid-base reaction withe the lewi catalyst.

– EWG groups include:
NO2, N(ch3)3, cooh, cor, cf3, so2h , nh2

What makes an aromatic ring much less reactive towards Friedel-Crafts alkylation or acylation?
Because they do not form carbocations readily
Why can’t aryl and vinyl halides be used in friedel crafts reactions?
– polyacylatiion does not occur because the acyl group deactivates the aromatic ring to further substitution
polyacylation occurs because frequency bc the first alkyl group introduced activates ther ring toward further substitution
Primary alkyl halides often rearranged products in Friedel Crafts alkylation — major limintation;
– reduction reduces phenyl ketones to the methylene (Ch2) group ;
What is the Clemmensen reduction?
more reactive than benzene
what happens to reactivity of benzene with an activating grop?
– Ch3, NH2, OH, F, Br, Cl,
Which groups are ortho-para directors?
-NO2, c=OOH, Hso3, Cl- , Br-, etc, NR3,+, CF3, CCL3
Which group are meta directors?
lithium tri-tertbutoxyaluminum hydride
What is the reducing agent to form aldehydes from acyl chlorides?
can be used to reduce ester to aldehyde at low temperature
What iS DIBAL-H?
Through ozonolysis of an alkene – O3 and Zn, HoAc –> ketone aldehyde
How do we synthesize ketones from alkenes, arenes, and secondary alcohols?
AlCl3 and acyl chloride
How do we synthesize aromatic ketones from Friedel Craft’s Acyalation?
How do we synthesize ketones from secondary alcohols
R2CuLi +RCOCl –> RCOR +RCu +LiCl
How did we form a ketone from a dialkyl cuprate to yield a ketone?
Addition does not occur twice because two negatie charges on teh nitrogen would result ;
Organolithium and Grignard’s reagents add to nitriles to form ketones
Aldehydes are generally more reactive than ketones
– the tetrahedral carbon resulting from addition to an aldehyde is less sterically hindered than the tetrahedral carbon resulting from addition to a ketone
– aldehyde carbonyl groups are more electron deficient because they have only one electron donating group attached to the carbonyl carbon.
Which are more reactive?
Hemiacetals are an aldehyde of ketone dissolved in an alcohol will form the hemiacetal; hydroxyl and alkoxyl group on the same carbo, –
acyclic hemiacetals are generlly not stable,
– however cyclic five and six-membered ring hemiacetals are.
What are hemiacetals and acetals?
when an aldehyde or ketone is in the presence of excess alcohol and an acid catalyst will form an acetal ; combo of acid catalysed and base catalysed reactions to form the acetals
Under what conditions will an acetal form?
H3O+ acetal plus H2o –> aldehyde, 2Roh
How do we convert an acetal into the corresponding aldehyde or ketone?
Why is acetal formation from ektones and simple alcohols less fravorable than formation from aldehyes?
Forming Cyclic 5 and 6 emmebered ring is favorable bc they are used as protecting groups for aldehyedes and ketones
– can be removed with aqueousacid okay

Protecting groups are the following: HOCH2CH2OH (excess)

Why is acetal formation from ektones and simple alcohols less fravorable than formation from aldehyes?
An ester can be reduced in the presnece of a keotne protected as an acetal; ; use LiAlH4 in Et2O as the reducer, used H2o work up and antoher H3o+ H2O WORKUP TO REMOFE THE acetal protecting group
What’s an exmaple of an acetal working as a protecting group?
Thioacetals can be converted to Ch2 groups by halogenation using a catalyst such as Raney Nickel
– this sequence provides a way to remove an aldehyde or ketone carbonl carbon
– 2 CH3CH2SH –> HA
– HSCH2CH2SH –BF3 –> cyclic thioacetal

Treat both with Raney Ni (H2) –> RCH2R H-CH2-CH2-H + NiS

What are thioacetals?
What happens when ketones and aldehydes react with primary amines?; secondary amines?
They yield imines; secondary amines yield enamines
What happens when ketones and aldehydes react with primary amines?; secondary amines?
Form cyanohydrin; a catalytic amount of cyanide helps speed the reaction ; cyanide nucleophilic attack at the carbonyl carbon; oxygen anion takes the H;
What happens when aldehyde and ketone react with HCN?
Aldehydes and ketones react with phosphorous ylide to prodcue alkenes
0- n
What is the Wittif reaction?

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