Organic Chemistry

_____ + _______ = hemiacetal

aldehyde/ketone + alcohol

_____ + ______ = hemiketal

ketone + alochol

what connects sugars

glycosidic bonds

what is this

keto enol tautomerism; fructose can act as a reducing sugar after tautomerization

what is this

basic structure of starch

during nucleophilic addition what would have the most reactivity and why?

an aldehyde (-CHO) because it has less steric hindrance, less electron donation

during nucleophilic addition what would have the least reactivity and why?

a ketone (C=O) two alkyl groups donate electron density and block attackbecause

_______ protect carbonyls because they are stable under basic conditions and hydrolyzed under acidic conditions.

acetals

____ + ____ = imine

Aldehyde/ketone + primary amine

____ + _____= enamine

Aldehyde/ketone + secondary amine

why do hydride reagents like NABH₄ and LiALH₄ due

they are reducing agents - they reduce carbonyls (add hydrogens)

NaBH₄

reducses aldehydes (-CHO) to primary Alcohols (-OH) and ketones (C=O) to secondary alcohols

NABH_{4 (milder reducing agent)}

what does LiALH₄ do

reduces aldehydes, carboxylic acids, esters → primary alochols, reduces amides, and reduces ketones → secondary alocholis

LiALH₄ (stronger reducing agent)

cyanohydrin formation - ketones and aldehudes reacting with cyanide. First step: nucleophilic attack. Second step: Deprotonation

Aldehydes can be oxidized to

carboxylic acids; RCHO → RCOOH

oxidation of aldehyde

attempted oxidation of ketone (ketones can not be oxidized under standard conditions because oxidation would require breaking a carbon-carbon bond.)

KMnO4 and CrO3/H2SO4

strong oxidizing agents

Jones reagent

oxidizing agent

effect: aldehyde → acid

tollens reagent

oxidizing agent

effect: aldehyde → acid, silver mirror

Benedict’s reagent

oxidizing agent

effect: detects reducing sugars/aldehydes

forms when a base removes an alpha hydrogen from a carbonyl compound.

enolate

The alpha carbon is the carbon

directly next to the carbonyl

Carbonyls make nearby hydrogens

more acidic

keto

enol

what form is favored more keto or enol?

keto, because the carbonyl bond is strong.

when do enols become more stable

conjugation (adding double bonds), aromaticity, intramolecular hydrogen bonding

the process where an optically active carbonyl compound with a chiral (alpha) -carbon converts into a 50/50 mixture of enantiomers

alpha racemization

_______ can racemize under acidic or basic conditions

Carbonyl compounds with chiral alpha carbons

aldol addition -  combines two aldehydes/ketones using an enolate.

general product of aldol addition

 β-hydroxy aldehyde or ketone carbonyl

aldol condensation, product: α,β-unsaturated carbonyl (dehydration reaction)

what is the key difference between aldol addition and aldol condensation

aldol addition product: beta-hydroxy carbonyl
adol condensatoin product: alpha,beta-unsaturated carbonyl

Retro-Aldol Reaction - reverse of aldol

aldol reaction

aldol reaction

kinetic enolate vs thermodynamic enolate

kinetic: forms fastest- less substituted, needs bulky/strong base, low temps

thermodynamic: more stable- more substitued, need small/reversible base, high temp

kinetic control - formed faster due to less steric hinderance at alpha carbon

thermodynamic control

A carbonyl is more reactive when the

carbonyl carbon is more electrophilic and less hindered.

what increases a carbonyls reactivity

Electron-withdrawing groups and positive charges nearby

what decreases a carbonyls reactivity

electron donating groups, steric hindrances, and resonsane donation into carbonyls

in order to count carbons you must do what

count how many carbons are connected to the other carbon

0 carbons attached

primary alcohol

secondary alcohol

secondary alcohol

outcome of oxidation of primary alcohol

aldehyde, then carboxylic acid

oxidation of secondary alochol

ketone

oxidation of tertiary alcohols

no oxidation under normal conditions

can LiAlH₄ , NaBH_4, Pd/C, DIBAL - H perform a reduction reactions with aldehydes (-CHO)?

yes

can LiAlH₄ , NaBH_4, Pd/C, DIBAL - H perform a reduction reactions with ketones (C=O) ?

yes

can LiAlH₄ , NaBH_4, Pd/C, DIBAL - H perform a reduction reactions with esters

only with LiAlH₄ and DIBAL - H

can LiAlH₄ , NaBH_4, Pd/C, DIBAL - H perform a reduction reactions with acids (-OH) ?

only with LiAlH₄ and DIBAL - H

can LiAlH₄ , NaBH_4, Pd/C, DIBAL - H perform a reduction reactions with acid chloride?

only with LiAlH_4, NaBH_4, and DIBAL - H

PCC, primary alochol → aldehyde

PCC - secondary alcohol → ketone

PCC, Jones reagent, KMnO_4, Na₂Cr₂O7/H₂SO​₄,

are all oxidizing agents (add O or take away H)

tertiary alcohol

primary alcohol

jones oxidiation. primary alochol → carboxylic acid

what resists oxidation and why

tertiary alcohols because the carbon bearing OH has no hydrogen to remove.

To react, OH usually must be

converted into a better leaving group which is done by protonation

describe SN1 alcohol substitution

favored by tertiary alcohol, weak nucleophile, polar protic solvent, acid catalyst

risks: rearrangements and racemization

2 steps

what are these examples of

• Water (H₂O)

• Methanol (CH₃OH)

• Ethanol (CH₃CH₂OH)

• Ammonia (NH₃)

polar protic solvents - favor SN1, slow down SN2 because they surround nucelophile

they are H bond donors and weakens nucleophiles

describe SN2 alcohol substitution

primary alcohol, needs strong nucleophile, converts to tosylate/mesylate, polar aprotic solvent

result: inversion of configuration if chiral center reacts

1 step

what are these examples of

• Dimethyl sulfoxide (DMSO)

• Acetone ((CH₃)₂CO)

• Acetonitrile (CH₃CN)

• DMF (dimethylformamide)

polar aprotic solvents - favor SN2

-does not hydrogen donate and keeps nucleophile strong

Alcohols can interfere with reactions because they are

nucelophilic/protic so protection temporarily masks OH

what are these examples of:

sillyl ethers and acetals/ketals

protecting groups - they temporality masks OH, to make alcohol less reactive (acetals/ketals protect carbonyls not alcohols directly)

a protected alcohol becomes

less reactive

what do meylates (MsCl) and tosylates (TsCl) do

convert OH into good leaving groups since OH is originally a bad leaving group

alkane → alkanoic acid =

ethanoic acid

ester

ester formation : Carboxylic acid + alcohol → ester + water.

amide formation: Carboxylic acid + amine → amide.

amide formation

Carboxylic acid + amine → amide.

“water is a byproduct” what does this mean

it is a condensation reaction

anhydride reaction. Two carboxylic acids can dehydrate to form an anhydride.

Anhydride Formation

Two carboxylic acids can dehydrate to form an anhydride.

usually does not reduce carboxylic acids.

NaBH₄

Decarboxylation - loss of carbon dioxdize

_______ decarboxylate easily because the transition state is stabilized.

beto-keto acids

how does Nucleophilic Acyl Substitution differ from aldehydes/ketones

aldehydes/ketones undergo nucleophilic addition

Relative Reactivity of Acid Derivatives

acid chloride > anhydride > ester ≈ carboxylic acid > amide

better leaving group =

more reactive

what makes a good leaving group

a weaker base, more acidic

Good ones: I⁻, Br⁻, Cl⁻, H₂O

Bad ones: OH⁻, NH₂⁻ (strong bases are unstable alone)

Transesterification - One ester is converted into another ester by exchanging the -OR group

hydrolysis of amides - converts amides into carboxylic acids and amines (or ammonia) using water, catalyzed by strong acid or base with heat

Amides require what to hydrolyze

strong acid or base and heat

acidic hydrolysis:

carboxylic acid + ammonium

basic hydrolysis

carboxylate + amine/ammonia

Penicillin contains a

beta-lactam ring which reacts with bacterial cell wall. beta lactams are make things more reactive

phenol

hydroquinone (reduced form) → quinone (oxidized form)

aromatic compounds -

not aromatic also can’t be open