Organic Synthesis Y1

Question 1

Draw a reflux set-up. Also state why reflux is used?

Answer 1

Look at PMT
To continually heat the contents of the flask. The condenser helps ensure the vapours condense and return to the flask for further heating. Ensure the product vapours can not escape

Question 2

Draw a Distillation set-up. And why is this technique used?

Answer 2

Look at PMT
Used to separate liquids with different boiling points. Condenser causes the vapour to condense back into a liquid, which is then collected in a separate flask.

Question 3

Describe the steps for preparation and purification of and organic liquid.

Answer 3

Separating Funnel - Separate two liquids with different densities. Stopper it and invert it to mix contents. allow liquids to separate into organic aqueous layers. Denser at the bottom and less dense at the top.

Drying with anhydrous salt - Use of MgSO4 or CaCl2

Re-distillation - Subsequent distillations can be carried out to obtain a purer product.

Question 4

How do I test for Alkenes/unsaturated compounds?

Answer 4

When you shake an alkene with orange bromine water, the solution quickly decolourises.
Because bromine is added across the double bond to forma colourless dibromoalkane

Question 5

How do I test for haloalkanes?

Answer 5

If you put silver nitrate solution AgNO3 and ethanol in the mixture, silver ions react with the halide ions as spam as they form giving a silver halide precipitate.
Iodoalkanes are most reactive and fluroalkanes are the least reactive.

Question 6

How do I get from an alkane to a haloalkane?

Answer 6

RTP, halogen and UV light

Question 7

How do I get from a haloalkane to an alcohol?

Answer 7

Reflux NaOH (aq)

Question 8

How do I go from a primary alcohol to an aldehyde. A carboxylic acid?

Answer 8

K2Cr2O7 / H2SO4 distillation.
To get carboxylic acid just reflux instead of

Question 9

How do I go from a secondary alcohol to a ketone?

Answer 9

K2Cr2O7 / H2SO4 reflux

Question 10

How do I go to an alcohol from a ketone and aldehyde?

Answer 10

Ketone - NaBH4 (aq), warm goes to secondary alcohol
Aldehyde - NaBH4 (aq), warm goes to primary alcohol

Question 11

How do I go from an alcohol to a haloalkane?

Answer 11

Sodium halide (NaX) / H2SO4 / HX , reflux

Question 12

How do I go from an alkene to an alkane?

Answer 12

H2/ Ni catalyst , 150degreescelcius (1000kPa)

Question 13

How do I go from an alkene to an alkane?

Answer 13

Hydrogen halide RTP

Question 14

How do I go from an alkene to an alcohol?

Answer 14

H2O (steam) / H3PO4, 300degreescelcius (60-70atm)

Question 15

How do I go from an alcohol to an alkene?

Answer 15

H3PO4 or H2SO4, heat (reflux)