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Chemistry module 4 > 4.2.3 organic synthesis > Flashcards

4.2.3 organic synthesis Flashcards

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1
Q

why are organic reactions commonly heated?

A

many occur slowly at room temperature so this overcomes activation energy and increases the rate of reaction

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2
Q

what is heating under reflux?

A

continual boiling and condensing of a reaction mixture back to its original container so the reaction takes place without contents of flask boiling dry

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3
Q

what apparatus is used to boil an organic liquid?

A

quick fit apparatus

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4
Q

what can be used to heat the reaction mixture in a reflux experiment?

A

bunsen burner, water bath if below 100℃, heating mantle

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5
Q

when would you specifically use a heating mantle as a heat source when preparing an organic liquid?

A

if you are using flammable liquids so no naked flames are present, adds safety if apparatus leaks or cracks

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6
Q

draw and label the apparatus needs to her under reflux

A

labels should include: noun-bottom/pear-shaped flask, condenser, rubber tubing, stand and clamp, heat source

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7
Q

Why are anti-bumping granules added to the reaction mixture?

A

so contents boil smoothly, bubbles could make mixture jump or vibrate

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8
Q

why is grease added to the glass joint of the condenser?

A

provides a good seal and comes off more easily

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9
Q

Why should u NEVER put a stopper in the top of the condenser ?

A

creates a closed system, pressure would build up and could cause explosion

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10
Q

what connects the condenser with water from the tap?

A

Rubber tubing

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11
Q

Does water enter the condenser at the bottom or the top and why?

A

the bottom, ensures outer jacket is always full

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12
Q

How does heating under reflux prevent substances from evaporating and the flask from boiling dry?

A

vapour rises until it meets outer jacket of cold water, it condenses and drips back into the flask

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13
Q

why is distillation used after reflux?

A

in reflux, reaction may not go to completion or by products may form. Distillation helps to remove these.

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14
Q

Draw and label the apparatus needed for distillation

A

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

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15
Q

what shape is a still head adaptor?

A

T - shape

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16
Q

water always enters the condenser…

A

at the lowest point

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17
Q

How does distillation help to separate out impurities in an organic liquid ?

A

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

18
Q

what occurs in the purifying process of an organic liquid?

A

water/aqueous layer is separated from the organic layer

19
Q

How would you know if you needed to purify your organic product?

A

if there are two liquid layers in the collection flask

20
Q

How do you know which layer is the aqueous layer during purification?

A

add some water to the mixture, the layer than gets bigger is the aq layer

21
Q

outline the purification procedure to purify organic liquid

A
  • 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
22
Q

How can you remove acid impurities from impure organic product?

A

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

23
Q

how can you remove traces of water from an organic liquid?

A

A drying agent

24
Q

what is a drying agent + examples

A

an anhydrous inorganic salt that can readily take uo water to become hydrated. eg magnesium sulphate, calcium sulphate

25
Q

procedure for drying an organic liquid

A
  • use spatula to add some agent to the liquid in a conical flask and swirl
  • use a stopper to prevent evaporation and leave for 10 minutes
  • solid in a lump = water still present. so, add more drying agent till solid is dispersed in the solution
  • decant/drain liquid from the solid
26
Q

How do you know if your organic liquid is dry?

A

should be clear

27
Q

Why is redistillation carried out?

A

some organic liquids have close boiling points so second distillation carried out to collect contents with the boiling point of your desired product and rid impurities

28
Q

what is the order of processes required to prepare an organic liquid?

A

heat under reflux, distillation , purification, drying and redistillation

29
Q

reagents and conditions for alkene to haloalkane (chloroalkane)

A

hydrogen halide (HCl) , room temp

30
Q

reagents and conditions for alkene to alkane

A
  • Hydrogen (hydrogenation)
  • Ni catalyst
  • 150℃
  • 5 atm
31
Q

reagents and conditions for haloalkane (chloro) to amine

A
  • excess NH3 (g)
  • ethanol solvent
  • heat under reflux then NaOH (aq)
32
Q

reagents and conditions for alcohol to alkene

A

dehydration
concentrated sulphuric/phosphoric acid catalyst
heat under reflux

33
Q

reagents and conditions for alkane to haloalkane

A

halogen, UV light (free radical substitution)

34
Q

reagents and conditions for alcohol to haloalkane

A
  • hydrogen halide or sodium salt and sulphuric acid in situ
  • heat under reflux
35
Q

reagents and conditions for alkene to alcohol

A
  • H2O steam
  • conc H3PO4 catalyst
  • 300-600℃ and high pressure
36
Q

reagents and conditions for secondary alcohol to ketone

A

acidified potassium dichromate [O]
heat under reflux

37
Q

reagents and conditions for haloalkane to alcohol

A

NaOH (aq)
heat under reflux

38
Q

reagents and conditions for primary alcohol to aldehyde

A

acidified potassium dichromate [O]
heat and distil

39
Q

what is a target molecule?

A

a compound you are trying to make through organic synthesis

40
Q

How do you carry out a two-step synthesis?

A

find functional group in start and end molecule
find the intermediate that would link those two together
identify reagents and conditions

Chemistry module 4 (1 decks)

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