Alcohols Flashcards
Phenol
Aromatic ring with a hydroxyl group
Particularly acidic because of resonance within the phenol ring
When a benzene ring contains two substituents we denote by
___ when they are adjacent
___ when they have 1 carbon separating them
___ when they are on opposite sides of the ring
Ortho-o
Meta-m
Para-p
What increases boiling point:
Hydrogen bonding from alcohols
Increased number of hydroxyl groups
Increased length of alkyl chain
Hydrogen bonding can increase:
Boiling point, melting point, solubility in water
When does hydrogen bonding occur
When hydrogen is bound to an EN atom such as F O N creating extreme polarity
Describe the oxidation of a primary alcohol by PCC? By other oxidizing agents
With PCC it is oxidized to an aldehyde and goes no further because pyridinium chlorochromate lacks the water necessary to hydrate aldehyde further
Other oxidizing agents allow thee aldehyde to be hydrated to form a geminal diol which is oxidized to a carboxylic acid
Describe the oxidation of secondary alcohols
Oxidized to ketones by PCC or any other strong oxidizing agent
Strong oxidizing agents may include sodium and potassium dichromate salts
What is Jones oxidation
Chromium trioxide (CrO3) is used as an oxidizing agent in dilute sulphuric acid in acetone Oxidizes primary alcohols to carboxylic acids and secondary alcohols to ketones
What are the two main functions of mesylates and tosylates
Reacted with alcohols to turn hydroxyl groups into better leaving groups for nucleophilic substitutions
To serve as protecting groups when we do not want alcohols to react as they do not react with many of the reagents that would attack alcohol
Describe how alcohols can be used as a protecting group
Aldehydes and ketones can be reacted with to equivalents of alcohol or a diol to from acetals or ketals
Acetals and ketals are not reactive with strong reducing agents like lithium aluminum hydride and therefore protect the aldehyde and ketone from reaction
After the reducing other functional groups the ketal or acetal can be reverted back to carbonyl with aqueous acid - deprotection
What happens when you treat a phenol with an oxidizing agent?
You get a quinone
What are the properties of quinones
They have a conjugated ring system so they are resonance stabilized electrophiles (not necessarily aromatic)
What is the biological function of quinones? Give some examples
They act as electron acceptors in the ECT
Eg. Phylloquinone (vitamin k1) important for photosynthesis and carboxylation of clotting factory
Menaquinones (vit k2)
What are hydroxyquinones? How are they formed?
Share the same ring and carbonyl backbone as quinones but they have the addition of 1 or more hydroxyl groups
They are formed by oxidizing quinones
Ubiquinone
Biologically active quinone. Aka coenzyme Q. It is an electron carrier in complexes I II III of the ECT. Most oxidized form
