Alcohols Flashcards
What are alcohols?
Organic compounds that contain one or more hydroxyl functional groups attached to a carbon atom
Classes of alcohol
Aromatic
Aliphatic
Difference between aromatic and aliphatic alcohol
Aliphatic have OH group attached to straight chain carbon, aromatic have OH group attached to benzene ring
The most widely used alcohols are
Methanol
Ethanol
2-propanol
Classes of aromatic alcohols
Primary
Secondary
Tertiary
Methanol use
Antifreeze
Dry gas
Both automotive products
Ethanol use
Solvent for drugs and chemicals
2-propanol use
Antiseptic
Phenols are…
The simplest form of aromatic alcohols
Difference between phenol and aliphatic alcohol
More acidic
Toxic
Causes skin burns
Uses of phenol derivative, thymol
To kill fungi and hookworms
One of the big differences between alcohols and hydrocarbons is…
Their ability to give and receive H bonds.
Effect of H bonds on alcohols
It increases the intermolecular force and therefore the mp and bp. It also allows them dissolve in water.
Tests for alchols
Sodium test Iodoform reaction Phenol test Jones’ oxidation reaction Lucas test
Sodium test for alcohol
Rapid evolution of H gas
Iodoform test for alcohol
Test is positive for a few specific secondary alcohols that contain at least, one methyl group in the alpha position.
Mechanism of iodoform test
When iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol, a pale yellow precipitate of iodoform or triiodomethane is formed.
How is the reagent for iodoform test obtained?
Iodine + NaOH
Iodoform test is also used to test for…
Methyl ketone
The only primary alcohol that gives positive iodoform test is…
Ethanol
What makes up Lucas reagent?
ZnCl2 in concentrated HCl
The Lucas test is based on…
The rate of reaction of alcohols to give alkyl halides
The reaction that occurs in the Lucas test can be seen as a
nucleophilic substitution reaction.
The observation of a change where the clear and colourless characteristic of the solution changes to a turbid, cloudy, and hazy one with Lucas test implies that
a chloroalkane has formed
Positive Lucas test is symbolized by…
White turbid, cloudy solution from colorless
Tertiary alcohol with Lucas test
They react the fastest due to the fact the organic chloride has relatively low solubility in the aqueous mixture.
Primary alcohol with Lucas test
The solution remains colourless unless it is subjected to heat. The solution forms an oily layer when heated
Secondary alcohol with Lucas test
The solution turns turbid and forms an oily layer in three to five minutes (varies based on the solubility)
Positive test for phenol is seen in…
Formation of a blue, violet, purple, green, or red-brown color upon addition of aqueous ferric chloride.
Cresol colour in phenol test
Blue
Beta naphthol colour in phenol test
Light green
Alpha naphthol colour in phenol test
Green
Hydroquinine colour in phenol test
Blue
Phenol colour in phenol test
Violet or purple
What is the colour of ferric chloride?
Yellow-orange
What makes up Jones reagent?
Chromic anhydride and dilute sulfuric acid (CrO3 + H2SO4 + H2O) in acetone
Positive Jones’ test for primary alcohol
Initially oxidized to aldehydes, then to carboxylic acids
Positive Jones’ test for secondary alcohol
The secondary alcohols are oxidized to corresponding ketones
Positive Jones’ test for tertiary alcohol
Not oxidized, no reaction
Positive Jones’ test for phenol
Oxidation to non-descriptive brown tarry mass
The reaction of an alcohol with sodium produces…
Sodium ethoxide and hydrogen gas
Relationship between alcohol acidity and reactivity with Na
The more acidic the alcohol, the faster the reaction
Which alcohol class is most acidic?
Primary, due to increased electron density on oxygen atom and stearic hindrance
Propan-1-ol
Monohydric, secondary aliphatic
2-methylbutan-2-ol
Monohydric, tertiary aliphatic
2-methylpropanol
Monohydric, primary
2-methylphenol
Aromatic/Phenolic
Pentan-2-ol
Monohydric, secondary aliphatic
