PAG 05 - Synthesis Of An Organic Liquid Flashcards
(25 cards)
Write equations of the reaction that takes place when cyclohexanol is dehydrated
Cyclohexanol —> cyclohexane + water
C6H11OH —> C6H10 + H2O
What is role of phosphoric acid in dehydration of alcohols
Catalyst (speeds up reaction rate)
When an alcohol is dehydrated, why do 2 layers form in separating funnel
Aq and organic layers have different densities and they’re immiscible
Why’s it important to open stopper of separating funnel regularly
Release build up of pressure and reduce risk of apparatus breaking
Cyclohexene can be procured from cyclohexanol. Why’s NaCl added to mixture before its separated with a separating funnel
To help remove most of water from solution
Cyclohexene can be produced from cyclohexanol. Why is anhydrous calcium chloride added to crude product
To remove final traces of water - acts as drying agent
When Cyclohexene is produced from cyclohexanol, is reflux or distillation apparatus used
Reflux
In purification of crude Cyclohexene, is reflux or distillation apparatus used
Distillation
What’s the purpose pf anti bumping granules
To prevent formation of large bubbles that cause violent boiling
During distillation, anti-bumping granules prevents mixture boiling over into condenser meaning impurities won’t contaminate the product
Describe key features of apparatus set-up distillation
Tilt the condenser down so any liquids flow into the beaker
The water must enter at the bottom of the condenser and leave at the top for efficient cooling
The collection flask should not be sealed to the condenser - it should not be airtight as the hot air in the system could cause the apparatus to crack
Use a thermometer to identify when the desired product has evaporated from the reaction mixture
How can percentage yield be calculated
Actual yeild
———————— x 100
Theoretical yeild
Describe chemical test for alkenes
Add bromine water
Colour change = orange —> colourless
Why might water bath or electric heater be used instead of a Bunsen burner to heat a reaction mixture
If reactants are flammable as using a Bunsen burner would be a safety risk
What safety precaution should be taken when carrying out this practical
- Cyclohexanol is harmful if inhaled or swallowed so keep lab well ventilated
- Concentrated phosphoric acid causes severe skin and eye burns so wear safety goggles and gloves when handling
- Anhydrous calcium chloride causes serious eye irritation so wear safety goggles
- Cyclohexene is fatal if swallowed so wash hands after use. It is also flammable so keep away from naked flames.
- Ensure the separating funnel stopper is firmly held in place and point the nozzle away from others when shaking
What type of reaction occurs when a haloalkane is formed from an alcohol
Nucleophilic substitution
Write the equations for the formation of
2-chloro-2-methyl propane from
2-methypropan-2-ol
2-methylpropan-2-ol + hydrochloric acid —>
2-chloro-2-methyl propane + water
CH3C(CH3)2OH + HCl —> CH3C(CH3)2Cl + H2O
Name 3 stages in synthesis of a haloalkane from an alcohol
- Preparation
- Separation
- Distillation
Why do 2 layers from in separating funnel when synthesising a haloalkane from an alcohol
Aq and organic layers have different densities and they’re immiscible
When producing a haloalkane from an alcohol, whys NaHCO3 added to organic layer after it has been separated from the aq layer
To react with any left over HCl
Why’s it important to pen the stopper of separating funnel regularly
To releases build up of pressure and reduce risk of apparatus breaking
When producing a haloalkane from an alcohol, why is anhydrous sodium sulfate added to organic mixture after separation
To remove water (small amounts only) -
Acts as a drying agent
Why is distillation used when synthesising a haloalkane from an alcohol
To separate + purify the organic product
Describe key feature of apparatus set-up for distillation
• Tilt the condenser down so any liquids flow into the beaker
• The water must enter at the bottom of the condenser and leave at the top for efficient cooling
• The collection flask should not be sealed to the condenser - it should not be airtight as the hot air in the system could cause the apparatus to crack
• Use a thermometer to identify when the desired product has evaporated from the reaction mixture
Why might a water bath or electric heater be used instead of a Bunsen burner to heat a reaction mixture
If reactants are flammable as using a bunsen Burner would be a safety risk
