21:Alcohols Flashcards
What is the functional group of alcohols
-OH
What are the physical properties of alcohols
Soluble in water (less soluble as the carbon chain gets longer)
Relatively low volatility (high boiling point)
How does the length of an alcohol’s carbon chain affect its solubility
Short chains are very soluble in water
Long chains are less soluble
Why are long chain alcohols less soluble in water
Because the alkyl group is non-polar and cannot form hydrogen bonds. e.g. octan-1-ol is only slightly soluble in water
Why are short chain alcohols very soluble in water
They can from hydrogen bonds to water
Why do alcohols have relatively high boiling points
The -OH group allows hydrogen bonding to occur and hydrogen bonds take more energy to break than induced dipole-dipole bonds.
What are the 2 methods of preparing alcohols
Hydration of alkenes
Hydrolysis of haloalkanes
What conditions are needed for the hydration of alkenes
A phosphoric acid catalyst
What type of reaction is the hydration of alkenes
electrophilic addition
What type of reaction is the hydrolysis of haloalkanes
nucleophillic substitution
What does the haloalkane react with in hydrolysis of a haloalkane
Its heated with water or with a aqueous alkali (like sodium hydroxide)
Equation for combustion of ethanol
C₂H₅OH +3O₂ → 2CO₂ +3H₂O
What is elimination
A reaction in which atoms are lost from the starting molecule without being replaced by new ones
What conditions are needed for the elimination of water from an alcohol to form an alkene
Heated with a concentrated acid usually conc. sulfuric acid or phosphoric acid
What does elimination of water from an alcohol form
an alkene
