4.2.3 organic synthesis Flashcards
(40 cards)
why are organic reactions commonly heated?
many occur slowly at room temperature so this overcomes activation energy and increases the rate of reaction
what is heating under reflux?
continual boiling and condensing of a reaction mixture back to its original container so the reaction takes place without contents of flask boiling dry
what apparatus is used to boil an organic liquid?
quick fit apparatus
what can be used to heat the reaction mixture in a reflux experiment?
bunsen burner, water bath if below 100℃, heating mantle
when would you specifically use a heating mantle as a heat source when preparing an organic liquid?
if you are using flammable liquids so no naked flames are present, adds safety if apparatus leaks or cracks
draw and label the apparatus needs to her under reflux
labels should include: noun-bottom/pear-shaped flask, condenser, rubber tubing, stand and clamp, heat source
Why are anti-bumping granules added to the reaction mixture?
so contents boil smoothly, bubbles could make mixture jump or vibrate
why is grease added to the glass joint of the condenser?
provides a good seal and comes off more easily
Why should u NEVER put a stopper in the top of the condenser ?
creates a closed system, pressure would build up and could cause explosion
what connects the condenser with water from the tap?
Rubber tubing
Does water enter the condenser at the bottom or the top and why?
the bottom, ensures outer jacket is always full
How does heating under reflux prevent substances from evaporating and the flask from boiling dry?
vapour rises until it meets outer jacket of cold water, it condenses and drips back into the flask
why is distillation used after reflux?
in reflux, reaction may not go to completion or by products may form. Distillation helps to remove these.
Draw and label the apparatus needed for distillation
labels should include: round-bottom/pear-shaped flask, condenser, rubber tubing, heat source, stand and clamp, screw-cap adaptor, receiver adaptor, still head adaptor, thermometer
what shape is a still head adaptor?
T - shape
water always enters the condenser…
at the lowest point
How does distillation help to separate out impurities in an organic liquid ?
different liquids in mixture will have different boiling points. lowest boiling point will boil first, condense and become a liquid to collect into a flask. can separate each liquid in mixture
what occurs in the purifying process of an organic liquid?
water/aqueous layer is separated from the organic layer
How would you know if you needed to purify your organic product?
if there are two liquid layers in the collection flask
How do you know which layer is the aqueous layer during purification?
add some water to the mixture, the layer than gets bigger is the aq layer
outline the purification procedure to purify organic liquid
- close tap of separating funnel
- pour mixture inside, add stopper and invert and allow to settle
- add water to see which layer is aq
- use conical flask, open tap and collect each layer separate and label
How can you remove acid impurities from impure organic product?
add sodium carbonate and shake in separating funnel. acid reacts and releases co2, let this out by inverting funnel and opening tap slowly. remove sodium carbonate layer and other layers separately
how can you remove traces of water from an organic liquid?
A drying agent
what is a drying agent + examples
an anhydrous inorganic salt that can readily take uo water to become hydrated. eg magnesium sulphate, calcium sulphate
