Orgo - Alcohols Flashcards
What is the general form of alcohols?
ROH
Alcohols are named with the suffix – ol.
How are alcohols named when they are not the highest priority functional group?
They are given the prefix hydroxy–
This indicates the presence of a hydroxyl group.
What are phenols?
Benzene rings with hydroxyl groups
They are named based on the relative positions of the hydroxyl groups.
What are the three positions of hydroxyl groups in phenols?
- ortho– (adjacent carbons)
- meta– (separated by one carbon)
- para– (on opposite sides of the ring)
These terms describe the relative positions of the hydroxyl groups on the benzene ring.
How does hydrogen bonding affect alcohols?
Raises boiling and melting points and increases solubility
Alcohols can hydrogen bond, which distinguishes them from alkanes.
Why are phenols more acidic than other alcohols?
The aromatic ring can delocalize the charge of the conjugate base with resonance
Like other alcohols, phenols form intermolecular hydrogen bonds and have relatively high melting and boiling points. Phenols are slightly soluble in water, owing to hydrogen bonding, as are some phenol derivatives. Because phenols are much more acidic than nonaromatic alcohols, they can form salts with inorganic bases such as NaOH.
This stabilization contributes to their acidity.
What effect do electron-donating groups have on acidity?
They decrease acidity
This is because they destabilize negative charges.
What effect do electron-withdrawing groups have on acidity?
They increase acidity
This is due to their ability to stabilize negative charges.
What can primary alcohols be oxidized to, and by which agent?
from alcohol to Aldehydes by weak KMnO4 /K2Cr2O7 / CrO3 etc
from alcohol to acid by strong pyridinium chlorochromate (PCC)
Stronger oxidizing agents will oxidize them to carboxylic acids.
What can secondary alcohols be oxidized to?
Ketones by any strong and weak oxidizing agent
This includes various oxidizing reagents.
What are mesylates and tosylates used for?
To make alcohols better leaving groups for nucleophilic substitution reactions
This enhances their reactivity in chemical reactions.
What functional group do mesylates contain?
–SO3CH3
Mesylates are derived from methanesulfonic acid.
What functional group do tosylates contain?
–SO3C6H4CH3
Tosylates are derived from toluenesulfonic acid.
What are acetals and ketals used for?
To protect aldehydes or ketones
They allow reactions with other functional groups without affecting the carbonyl.
How is an acetal formed?
By reacting two equivalents of alcohol with a carbonyl
The product has a primary carbon with two –OR groups and a hydrogen atom.
What is deprotection in the context of acetals or ketals?
Converting acetal or ketal back to a carbonyl by catalytic acid
This allows access to the original carbonyl compound.
How are quinones synthesized?
Through oxidation of phenols
Quinones are resonance-stabilized electrophiles.
Name two examples of biochemically relevant quinones.
- Vitamin K1 (phylloquinone)
- Vitamin K2 (menaquinones)
Both are important for biological functions.
What are hydroxyquinones?
Produced by oxidation of quinones, adding a variable number of hydroxyl groups
They are derivatives of quinones.
What is ubiquinone and its role?
A biologically active quinone that acts as an electron acceptor in the electron transport chain
Ubiquinone is also known as coenzyme Q.
What does ubiquinone reduce to?
Ubiquinol
This reduction is part of its function in cellular respiration.
can tertiary alcohols be oxidized?
Tertiary alcohols, in contrast, cannot be oxidized without breaking the molecule’s C–C bonds.
What is oxidation?
Loss of electrons, fewer bonds to hydrogens, more bonds to heteroatoms (O, N, halogens)
Oxidation involves the increase in oxidation state due to the loss of electrons.
What is reduction?
Gain of electrons, more bonds to hydrogens, fewer bonds to heteroatoms
Reduction results in a decrease in oxidation state due to the gain of electrons.
What are good oxidizing agents?
- O2
- O3
- Cl2
- Mn7+ in permanganate (MnO4—)
- Cr6+ in chromate (CrO4)
Good oxidizing agents have a high affinity for electrons or unusually high oxidation states.
What characterizes a good reducing agent?
Low electronegativities and ionization energies
Good reducing agents readily donate electrons.
List some common reducing agents.
- Sodium
- Magnesium
- Aluminum
- Zinc
- Metal hydrides (e.g., NaH, CaH2, LiAlH4, NaBH4)
Metal hydrides are particularly effective due to the presence of the H– ion.
Fill in the blank: A good oxidizing agent has a high _______ for electrons.
[affinity]
The stronger the affinity, the more effective the oxidizing agent.
True or False: Reduction involves an increase in oxidation state.
False
Reduction corresponds with a decrease in oxidation state.
What can alcohols be converted to in order to make them better leaving groups for nucleophilic substitution reactions?
Mesylates or tosylates
Mesylates are derived from methanesulfonic acid, while tosylates are derived from toluenesulfonic acid.
What are mesylates derived from?
Methanesulfonic acid
Mesylates have the chemical structure –SO3CH3.
What are tosylates derived from?
Toluene sulfonic acid
Tosylates have the chemical structure –SO3C6H4CH3.
How can alcohols be used as protecting groups for carbonyls?
By reacting with a dialcohol to form an unreactive acetal
The protecting group can later be removed with aqueous acid.
Fill in the blank: Alcohols can be converted to _______ or tosylates to improve their leaving group ability.
Mesylates
True or False: Alcohols can form reactive acetals when used as protecting groups for carbonyls.
False
Alcohols form unreactive acetals when used as protecting groups.
What is produced by the treatment of phenols with oxidizing agents?
Quinones
Quinones are a class of cyclic organic compounds derived from phenols.
What are the two oxidizing agents mentioned for the treatment of phenols?
Na2Cr2O7 and H2SO4
These agents facilitate the oxidation process to form quinones.
What can quinones be further oxidized to form?
Hydroxyquinones
Hydroxyquinones are a class of molecules derived from the oxidation of quinones.
What is ubiquinone also known as? and role in ETC?
Coenzyme Q (Q cycle in ETC!})
Vital electron carrier associated with Complexes I, II, and III
ubiquinone is considered a “2e carrier”
Ubiquinone is essential for cellular respiration as an electron carrier.
What can ubiquinone be reduced to?
Ubiquinol
Ubiquinol is the reduced form of ubiquinone and plays a role in energy production.
What is the process called when ubiquinol is reoxidized to ubiquinone?
Q cycle
The Q cycle describes the transfer and recycling of ubiquinone and ubiquinol in the electron transport chain.
What effect does hydrogen bonding have on melting points, boiling point, solubility in water?
Increased melting points, boiling points, solubility in water
Hydrogen bonding contributes to stronger intermolecular forces, leading to higher melting points.
What is the relationship between the number of hydroxyl groups and hydrogen bonding?
More hydroxyl groups lead to greater degrees of hydrogen bonding
Molecules with multiple hydroxyl groups can form more hydrogen bonds, affecting their physical properties.
Fill in the blank: Molecules with more than one _______ show greater degrees of hydrogen bonding.
hydroxyl group
Hydroxyl groups (-OH) are key sites for hydrogen bonding in organic molecules.
How does the presence of alkyl groups affect acidity?
Acidity decreases as more alkyl groups are attached because they are electron-donating, which destabilizes the alkoxide anion.
What type of groups stabilize the alkoxide anion?
Resonance or electron-withdrawing groups stabilize the alkoxide anion.
What does the Jones oxidation do to primary alcohols?
uses chromium trioxide, CrO3 dissolved in dilute sulfuric acid with acteone
Oxidizes primary alcohols to carboxylic acids
oxidizes secondary alcohols to ketones
