Alcohols Flashcards
What are the conditions for formation of alcohols from halogenoalkanes and what type of reaction is it
Reflux with sodium hydroxide aqueous and 1 atmosphere
NUCLEOPHILIC substitution or alkaline hydrolysis
Give reaction equation for the formation of alcohols from halogenoalkanes
RX + NaOH –> ROH + NaX
Reaction of alcohols with hydrogen bromide
How is HBr produced?
What do they produce?
HBr produced in the reaction flask by refluxing with concentrated sulfuric acid and KBr
Produce bromoalkanes
Reactions of alcohols with hydrogen chloride
Conditions
Reaction equation
What they produce
Anhydrus, ZnCl2 catalyst
NUCLEOPHILIC substitution
ROH + HCl –> RCl + H2O
Produce chloroalkanes e.g 2-chlorobutane
Reduction reaction to form alcohol:
What is a carboxylic acid reduced to? Give equation
Reduced to 1• alcohol
RCOOH—> [4H] RCH2OH + H2O
Reduction reaction forming an alcohol
What is an aldehyde reduced to
Reaction equation
Reduced to 1• alcohol
RCHO —> [2H] RCH2OH
Reduction RXN to form an alcohol
What is a ketone reduced to?
Reaction equation
Reduced to 2• alcohol
RCOR’ —-> [2H] RCH(OH)R’
2 Reducing agents for reduction reactions
Lithium aluminium hydride - anhydrous, room temp, works for all
Aqueous sodium borohydride - room temp and only reduces aldehydes and ketones
Conditions for alcohols and ethanoyl chloride
Basic catalysts to neutralise acidic hydrogen chloride
Anhydrous
What does alcohols and ethanoyl chloride produce? What type of reaction is it?
An eater, it’s a NUCLEOPHILIC substitution / ethanoylation reaction
What are the properties of an acid catalyst eg ethanoyl chloride
Fuming liquid
Low BP
No hydrogen bonding between molecules
Alcohols are neutral in terms of acidity in something - what is this something?
Aqueous solution
What bonding is present between alcohol molecules?
Hydrogen
What is the polarity of the hydroxy group?
It is polar due to an electronegativity difference between O and H atoms. This leads to a permanent dipole which results in hydrogen bonding between molecules
Solubility of alcohols in terms of Boiling point
Solubility decreases as boiling point increases due to an increase in VDW between molecules: more energy to overcome forces
Solubility of alcohols in terms of molar mass/hydrocarbon chain
Solubility decreases as molar mass increases due to the increasing effect of the hydrocarbon chain over the effect of the hydroxy group which can hydrogen bond to water molecules
Explain the boiling points of alcohols
They’re higher than expected from their Mr’s because the Hydroxy group can hydrogen bond to hydroxy group of other molecules which increases the intermolecular forces and lots of energy is needed to overcome them
Triiodomethane iodoform test for an alcohol -
Reagents?
Positive result with what group?
Observation?
Iodine and sodium hydroxide (aq)
Positive result seen with group CH3COH
Observe: yellow ppt (and antiseptic smell buy not observation)
What primary alcohol is the only primary alcohol to give a positive result with iodine and sodium hydroxide?
Do tertiary alcohols?
Ethanol
Tertiary alcohols don’t produce positive result
What is the catalyst used in the ESTERIFICATION of alcohols and carboxylic acids?
Concentrated sulfuric acid catalyst
What is a characteristic of an water
Sweet smell
Describe reagents and conditions for reactions of alcohols and carboxylic acids
Alcohol
Carboxylic acid
Concentrated sulfuric acid catalyst
Explaining the difference in boiling points between two similar molecules
Less dipole dipole forces between molecules of one so less energy to overcome so lower BP
Give a reason why a main product of a reaction between propene and water under conditions such as electrophilic addition is propan-2-ol?
Secondary carbocation nor eatable than primary carbocation
