Module 4 Chapter 16

This is for making carboxylic acids from primary alcohols, ketones from secondary alcohols, dehydration of alcohols and substitution of alcohols.

It overcomes the activation energy increasing the rate of reaction

It doesn’t aggressively boil reactants and products

Round-bottom or pear shaped flask Condenser Rubber tubing Stand and clamp Heat source - usually a Bunsen burner, tripod and gauze

It is carried out at a fixed temperature If it is under 100 degrees a water bath can be used And a heating mantle can be used for flammable liquids Anti bumping granules can be added to flask so the contents will boil smoothly

It is kept upright and clamped loosely as the outer glass is fragile No stopped on top of the condenser to prevent the build up of pressure Water enters at the bottom and exits at the top of the Leibig condenser

The vapour rises and then passes into the condenser where it is cooled and drips back into the flask

It is a method to separate a pure liquid from its impurities

Condenser Round bottom or pear shaped flask Rubber tubing Heat source Stand and clamp Thermometer Still head Receiving adapter Screw cap adapter

The flask is clamped by neck and still head connected to the flask The still head adapter is T shaped and has two joints one for the screw cap adapter and one for the condenser The second clamp is placed and the round receiver adapter at the point at which it is attached to the condenser

A flask is used to collect the distillate

The flask is heated and the mixture will start to boil Different liquids in the mixture will have different BPs Lowest BP is the most volatile and boils first Vapour moves out of the flask and into the condenser where it will cool back to a liquid and drip into the collecting flask.

Using a separating funnel

1)Ensure the tap of the separating funnel is closed 2)Pour the mixture of liquids into the separating funnel and place a stopper at the top of the funnel, invert to mix 3) allow the layers to settle 4) add some water to see which layer increases in volume and this is the aqueous layer

• Place a conical flask under the separating funnel, remove the stopper and open the tap until the whole of the lower layer has left the funnel • Place a second conical flask under the separating funnel to collect the other layer • Have one conical flask with the organic layer and one with the aqueous labelled properly

Preparation of organic liquid often involves acids, so there may be acids in your impure product.

Add aqueous sodium carbonate, shake in a separating funnel The acid will react with the sodium carbonate forming carbon dioxide gas Open the tap slowly holding the separating funnel upside down to release any gas produced Use the separating funnel to remove the aqueous sodium carbonate layer and the organic layer should be washed with water before running both layers off

Add a drying agent to the organic liquid - anhydrous inorganic salt This readily takes up water becoming hydrated.

1) Add organic liquid to conical flask 2) using spatula add during agent to liquid and gently swirl to mix 3) Place stopper on flask - stopping evaporation and leave for 10 minutes 4) If solid is in one lump there is still water add move or the drying agent until some of the solid is dispersed in the solution as fine powder 5) Decant liquid from solid into another flask, if liquid is dry it should be clear.

Anhydrous calcium chloride - drying hydrocarbons Anhydrous calcium sulphate - general drying Anhydrous magnesium sulphate - general drying

Some organic liquids have boiling points that are very similar So the sample may be impure

Clean and dry the distillation apparatus for carrying out a second distillation Now only collect the product with the boiling points of the desired compounds The narrower the boiling range the purer the product.