L.10 Alcohols Flashcards Preview

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Flashcards in L.10 Alcohols Deck (12)
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1

Alcohols

General Form

Pka

Group

Suffix

Prefix

Priority

  • ROH
  • pKa = 16
  • Group = hydroxyl (-OH)
  • Suffix  = -ol
  • Prefix = Hydroxy-
  • Higher priority than double or triple bonds and alkanes
  • Diols = Two hydroxyls, geminal same carbon -or- vicinal if on adjacent

2

Structure of a PHENOL

Benzene Rings with Hydroxyl Groups

3

How are Phenols Named?

Phenols are named by their relative position of the hydroxyl groups with any other attached molecule.

 

ortho- ADJACENT 

meta- SEPARATED BY 1 CARBON

para- ON OPPOSITE SIDES OF THE RING

4

Physical Properties of Alcohols & Phenols

Alcohols; hydrogen bonding ( F O N ) raises their boiling/melting points relative to there corresponding alkanes. Also increases solubility.

Phenols; hydrogen on the phenol is more acidic b/c the electron on the oxygen is resonance stabilized by the benzene ring. (Aromatic ring can delocalize the charge of the conjugate base)

 

Electron-donating groups like alkyl groups decrease acidity because they destabilize negative charges. Electron-donating groups, such as electronegative atoms and aromatic rings, increase acidity because they stabilize negative charges

5

Oxidation Reactions of 1°ALCOHOLS

1° Alcohols  

PCC (mild oxidant) = Aldehyde

Chromium (strong) = Carboxylic Acid

Jones Oxidation CrO3 + H2SO4 + Acetone (strong)  = Carboxylic Acid

6

Oxidation Reactions of 2º ALCOHOLS

2º Alcohols

PCC (mild) = Ketones

K/Na2Cr2O7 + H2SO4 (stong) = Ketones

CrO3 + H2SO4 + Acetone (strong) = Ketones

7

Oxidation Reactions of 3º Alcohols

Cannot be further oxidized

8

What are Mesylates & Tosylates?

Alcohols can be converted to mesylates and tosylates to make them better-leaving groups for nucleophilic substitution reactions.

Mesylates contain the functional group -SO3CH3, which is derived from methanesulfonic acid.

Tosylates contains the functional group -SOC6H4CH3, which is derrived from toluenesulfonic acid.

9

Explain the conversion of alcohols into protecting groups.

  • Two equivalents of alcohol or a dialcohol can be reacted

with the carbonyl of an aldehyde or ketone to

form an ACETAL or KETAL respectively.

  • Then, other groups in the compound can be reacted (especially by reduction with Lithium aluminum hydride ) without affecting the newly formed acetal or ketal.
  • The acetal or ketal can be regenerated back to carbonyls with

catalytic acid, which is called deprotection.

10

How are QUINONES produced?

  • Phenol + Oxidizing Agents = Quinones
  • Quinones are resonance-stabilized electrophiles
  • Vitamin K1 (phylloquinone) & K1 (menaquinone) are examples of biochemically relevant quinones.

(photosynthesis + carboxylation of blood clotting factors)

 

11

What is UBIQUINONE? & How is it useful?


Ubiquinone, also known as COENZYME Q is a biologically active quinone that acts as an electron acceptor in complexes I II & III of the electron transport chain. 

Thus,

It is reduced to UBIQUINOL, which is an electron carrier within the phospholipid bilayer (long alkyl chain = lipid soluble)

12

Can Quinones be further oxidized?

Yes, they are further oxidized to form HYDROXYQUINONES.

  • Used for the synthesis of medications
  • Two carbonyls + HYDROXYL GROUP
  • Less electrophilic, but still very reactive

 

2-HYDROXY-1,4-BENZOQUINONE

(If more than one hydroxyl group then, di-, tri-, etc.)