Procedure for steam distillationProcedure for steam distillationBy: Dr. Robert D. Craig, Ph.DBy: Dr. Robert D. Craig, Ph.D

Procedure for steam distillationProcedure for steam distillation

In the assembly shown, steam is passed In the assembly shown, steam is passed into a 250 mL round bottomed flask into a 250 mL round bottomed flask through a section of 6 mm glass tubing through a section of 6 mm glass tubing fitted into a still head with a piece of 5 mm fitted into a still head with a piece of 5 mm rubber tubingrubber tubing

Procedure for steam distillationProcedure for steam distillation

Procedure for steam distillationProcedure for steam distillation

This is then connected to a steam lineThis is then connected to a steam line

Procedure for steam distillationProcedure for steam distillation

The trap serves two purposes:The trap serves two purposes:

(1) it allows water, which is in the steam line (1) it allows water, which is in the steam line to be removed before it reaches the round to be removed before it reaches the round bottomed flask and bottomed flask and

(2) adjustment of the clamp on the hose at (2) adjustment of the clamp on the hose at the bottom of the trap allows precise the bottom of the trap allows precise control of the steam flow.control of the steam flow.

Procedure for steam distillationProcedure for steam distillation

A bent adapter attached to a long condenser A bent adapter attached to a long condenser delivers the condensate into a 250 ml delivers the condensate into a 250 ml Erlenmeyer flask.Erlenmeyer flask.

Steam Distillation Steam Distillation

Steam DistillationSteam Distillation

On page 113!On page 113! Using a graduated cylinder, measure out Using a graduated cylinder, measure out

10 mL of Lemongrass oil (not lemon oil) 10 mL of Lemongrass oil (not lemon oil) into a 250 mL boiling flask.into a 250 mL boiling flask.

Rinse the remaining conentents of the Rinse the remaining conentents of the graduated cylinder into the flask with a graduated cylinder into the flask with a small amount of t-butyl methyl ethersmall amount of t-butyl methyl ether

t-butyl methyl ether!t-butyl methyl ether!Will be used to recover citralWill be used to recover citral

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Steam DistillationSteam Distillation

Add 100 mL of water, make the Add 100 mL of water, make the connections as in Figure 6.4, heat the connections as in Figure 6.4, heat the flask with a low flame, and pass in the flask with a low flame, and pass in the steamsteam

Steam DistillationSteam Distillation

To start the steam distillation, heat the To start the steam distillation, heat the flask containing the mixture on the flask containing the mixture on the Thermowell to prevent water from Thermowell to prevent water from condensing in the flask to the point wher condensing in the flask to the point wher water and product splash over into the water and product splash over into the receiver.receiver.

thermometers, thermocouples, thermometers, thermocouples, and bulbsand bulbs

A thermowell allows the temperature A thermowell allows the temperature sensor to be removed and replaced sensor to be removed and replaced without compromising either the ambient without compromising either the ambient region region

Steam DistillationSteam Distillation

Turn on the steam valve, being sure that Turn on the steam valve, being sure that the screw clampl on the bottom of the trap the screw clampl on the bottom of the trap is open.is open.

Slowly close the clamp and allow steam to Slowly close the clamp and allow steam to pass into the flask.pass into the flask.

Steam DistillationSteam Distillation

Try to adjust the rate of steam addition Try to adjust the rate of steam addition and the rate of heating so that the waster and the rate of heating so that the waster level in the flask remains constant.level in the flask remains constant.

Steam DistillationSteam Distillation

Unlike ordinary instillations, steam Unlike ordinary instillations, steam distillations are usually run as fast as distillations are usually run as fast as possible, with proper care to avoid possible, with proper care to avoid splashing of material into the receiver and splashing of material into the receiver and the escape of uncondensed steam.the escape of uncondensed steam.

Distill as rapidly as the cooling facilities Distill as rapidly as the cooling facilities allow and continue until droplets of oil no allow and continue until droplets of oil no longer appear at the tip of the condenser.longer appear at the tip of the condenser.

ExtractionExtraction

Pour 50 mL of t-butyl methyl ether into a Pour 50 mL of t-butyl methyl ether into a 125 mL separatory funnel, cool the 125 mL separatory funnel, cool the distillate and pour a part of it into the distillate and pour a part of it into the funnelfunnel

separatory funnelseparatory funnel

ExtractionExtraction

Shake the funnel, and let the layers Shake the funnel, and let the layers separate, discard the lower layer, add separate, discard the lower layer, add another portion of distillate and repeatanother portion of distillate and repeat

ExtractionExtraction

When the last portion of distillate has been When the last portion of distillate has been added, rinse the flask with a small amount added, rinse the flask with a small amount of t-butyl methyl ether to recover adhering of t-butyl methyl ether to recover adhering citralcitral

ExtractionExtraction

Use the techniques described in chapter 7 Use the techniques described in chapter 7 for drying, filtering, and evaporating the t-for drying, filtering, and evaporating the t-butyl ether.butyl ether.

ExtractionExtraction

Take the tare of a 1-g tincture bottle,Take the tare of a 1-g tincture bottle,

transfer the citral to it with a pasture pipette, transfer the citral to it with a pasture pipette,

and determine the weight and yield from the and determine the weight and yield from the

lemongrass oil.lemongrass oil.

ExtractionExtraction

Label the bottle and store (in the dark) for Label the bottle and store (in the dark) for later testing for the presence of double later testing for the presence of double bonds (alkenes) and aldehyde groupsbonds (alkenes) and aldehyde groups

ExtractionExtraction

Looks like that’s it!Looks like that’s it!

Recovery of a Dissolved Recovery of a Dissolved Substance!Substance!

Should continue this???Should continue this???

Hit the lab!!!Hit the lab!!!

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