CHM 242 Quiz 1 Spring 2025 Erb

Alcohols posses a

hydroxyl group

Phenols possess a

hydroxyl group attached to an aromatic ring

Methanol

the simplest alcohol and is quite poisonous, but has many uses as: fuel, solvent, and precursor in synthesis

Ethanol

produced by fermentation. It's uses include: solvent, fuel, synthetic precursor, and as a beverage

Isopropanol

made from acid catalyzed hydration of propene and is used as an antiseptic, fuel additive, and solvent

The more electronegative an atom is

the more stable it is

Strong Acids are

very unstable and therefore have very stable conjugate bases

A bigger atom (or more polarizable atom) is

more stable

More resonance in an acids conjugate base makes it a

stronger acid

What types of strong bases are required to deprotonate an alcohol?

C-, N-, or H- base

What are the three factors that generally affect the acidity of alcohols and phenols

resonance, induction, and solvation effects (bulkiness)

Resonance stabilizes the conjugate base of phenols by

delocalizing the electrons on the oxygen atom

More induction in an acids conjugate base =

more acidic

Less sterically hindered conjugate bases are more solvated which

means their acid is stronger

Preparation of an alcohol using substitution is only practical for

primary (SN2) and tertiary (SN1) substrates

A secondary substrate is not effective at creating an alcohol via substitution because

The use of NaOH with SN2 would favor E2 and SN1 would be too slow

Acid-catalyzed Hydration Reagent

dilute H2SO4

Acid-catalyzed Hydration Regiochemistry

Markovnikov

Acid-catalyzed Hydration Stereochemistry

racemic mixture

Acid-catalyzed Hydration Intermediate

carbocation

Oxymercuration-Demercuration Regiochemistry

Markovnikov

Oxymercuration-Demercuration Stereochemistry

Anti addition

Oxymercuration-Demercuration Intermediate

cyclic

Hydroboration-Oxidation Regiochemistry

Anti-Markovnikov

Hydroboration-Oxidation Stereochemistry

Syn addition

Hydroboration-Oxidation Intermediate

None, its concerted

Oxidation

increases the number of bond between carbon and a more electronegative atom and/or decreases the number of C-H bonds

Reduction

decreases the number of bonds to more electronegative atoms and/or increases the number of C-H bonds

What are the three most common reducing agents for ketone to alcohol reduction

NaBH4, LAH, and Hydrogenation (H2 and Lindlar's catalyst)

What is the strength of sodium borohydride (NaBH4)?

mild

What is the strength of lithium aluminum hydride (LAH)?

strong

Hydrogenation of a ketone to form an alcohol requires, what conditions?

harsh conditions

Mechanism of NaBH4 ketone reduction

Nucleophilic attack then proton transfer

NaBH4 reductions works on

aldehydes and ketones

LAH reduction works on

ketones, esters, and carboxylic acids

LAH Reduction Mechanism

Nucleophilic attack then proton transfer

Why is LAH reduction done in two distinct steps?

the LAH and protic H2O would react

LAH Reduction Mechanism for Carboxylic Acids and Esters

nucleophilic attack, loss of a leaving group, nucleophilic attack and then proton transfer

Why is excess LAH required for COOH and Ester reduction?

there is two nucleophilic attack steps

Is NaBH4 strong enough to reduce carboxylic acids and esters?

NO

What is the major advantage of hydride delivery agents?

they selectively reduce carbonyls. No C-C bonds are reduced

Grignard Reagent

formed by the reaction between an alkyl halide and magnesium

What is the key characteristic of a Grignard reagent?

C-Mg bond

The inductive effects of between the magnesium and carbon make the bond be considered

ionic

When preparing alcohols via a Grignard Reagent the carbon serves as a

carboanion nucleophile

Preparation of an alcohol via Grignard Reagent Mechanism

nucelophilic attack followed by neutralizing proton transfer

Preparation of an alcohol via Grignard Reagent for Ketones and Aldehydes has what type of intermediate?

tetrahedral intermediate with no leaving group

Grignard Reagents

carbon nucleophiles capable of attacking a wide range of electrophiles, including carbonyl groups

Why is water in a separate step when using a Grignard Reagent?

because the water would react with the grignard reagent

RMgX =

good nucleophile/base

Grignard Reagents cannot form alcohols in the presence of what functional group?

carboxylic acids

Preparation of an Alcohol via Grignard Reagent for Esters Mechanism

Nucleophilic attack, loss of a leaving group, nucleophilic attack, and proton transfer

Ethers are used for what in the Grignard reaction?

a stabilizing solvent

Reactants with an alcohol act as what in the presence of reactive reagents?

an acid

How is alcohol reactivity prevented?

by protecting it

Protection of Alcohols

1. (Protect) remove the hydroxyl groups proton and convert it to a new group

2. Perform the Grignard reaction

3. (Deprotect) convert the protecting group back into a hydroxyl group

Mechanism for Alcohol Protection

SN2 that binds trimethylsilyl ether (TMS) where the alcohol was to form OTMS

How is OTMS removed from a molecule?

By reacting it with H3O+ or F- (tetrabutylammonium fluoride)(TBAF)

Tertiary Alcohols undergo a ___ reaction when treated with HX to give an alkyl halide

SN1

Primary and secondary alcohols undergo substitution when

the alcohol is converted to a tosylate and followed by nucleophilic attack or they are reacted with SOCl2 or PBr3 (both of these are SN2 pathways)

HBr and ZnCl2 can only be used to substitute what type of alcohols?

primary

Under what conditions can alcohols undergo elimination?

acidic

E1 should only be used to eliminate what type of alcohols because of carbocation rearrangement?

tertiary

If the alcohol is converted into a better leaving group, then a _______ ________ can be used to promote E2.

strong base

If you see lots of oxygen atoms in a molecule it might be an indicator of what type of reaction?

oxidation

What are the two methods for producing chromic acid?

Chromium tetroxide(CrO3) reacting with H3O+ in an aprotic solvent and sodium dichromate (Na2Cr2O7) reacting with H2SO4 in a protic solvent

What are the two steps in oxidizing an alcohol?

forming the chromate ester and then using an E2 process to form the carbon to oxygen pi bond

Oxidation of a primary alcohol proceeds to

aldehydes and subsequently to carboxylic acids

Oxidation of a secondary alcohol produces a

ketone

What type of alcohols do not undergo oxidation?

tertiary alcohols

What is the oxidizing agent that can stop at an aldehyde?

PCC (pyridinium chlorochromate)

What is the strength of PCC?

mild

What is the strength of Na2Cr2O7?

strong

Ether

an oxygen atom that is bonded between two -R groups

Ether R groups can be

alkyl, aryl, or vinyl

Ethers act as a hydrogen bond _________ in the presence of a hydrogen bond _______, such as an alcohol.

acceptor, donor

The size of an ethers side chain has a big impact on what IMF?

dispersion forces

Ethers with large side chains have (high/low) boiling points.

High

What are the two steps of the William Ether Synthesis?

1) deprotonation of the alcohol to form an alkoxide anion

2) nucleophilic attack of a methyl or primary alkyl halide by the alkoxide anion

What type of alkyl halide is able to react in the William Ether synthesis?

methyl or primary

What type of bases are able to deprotonate an alcohol?

N-, C-, or H-

Doing oxymercuration-mercuriation with an alcohol solvent produces what functional group as a product?

an ether