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james smith lab > lab > Flashcards

lab Flashcards

1
Q

Sodium Hydroxide _______________

A
  • corrosive- causes burns
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2
Q

Gramine is _________________

A

Harmful -if swallowed or in contact with skin

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3
Q

Indole is ____________-#

4

A

3 Harmful- in contact with skin and if swallowed. Irritant. May cause serious eye damage

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4
Q

Indole is ____________

A

Harmful- in contact with skin and if swallowed. Irritant. May cause serious eye damage

AQATIC LIFE

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5
Q

Dimethylamine is __________________

4

A

Highly flammable. Harmful by inhalation and if swallowed.

Corrosive causes burns

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6
Q

Petroleum ether is _____________

5

A

Highly flammable. Harmful. May cause lung damage if swallowed. Do not breathe gas. Avoid skin contact, DROWSY

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7
Q

Acetone is _____________

3

A

Highly flammable- irritating to eyes, DROWSINESS

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8
Q

Formaldehyde is ___________

7

A 
Toxic by Inhalation, Skin contact and if swallowed 
Dangers of irreversible effects
Corrosive 
Carcinogenic category 3
Caused burns
Sensitization by skin contact
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9
Q

how did the recrystallization happen

A

Boiling mixture used for recrystalization
Pet ether 40ml
Then add 5ml acetone

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10
Q

describe the principle of recrystallization

A

Principle of crystallisation

To purify the product by reforming the crystal with impurities remaining in solution

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11
Q

Why use a Boiling stick?

A

So solvent will boil evenly and will not boil over

Gramine is very soluble in acetone

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12
Q

Slower cooling produces _________________

A

better quality crystals formed

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13
Q

What chemicals in the synthesis of Gramine require students to wear gloves AND handle in the fume cupboard.

A
  • Indole
  • Dimethylamine
  • Formaldehyde
  • Acetic acid
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14
Q

What chemicals in the synthesis of Gramine require students to JUST wear gloves

A
  • NaOH
  • Petroleum ether
  • Acetone
  • Gramine
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15
Q

Why does the dimethylamine, formaldehyde, and glacial acetic acid need to be ice-cooled?

A

The iminium ion only forms when it is cold

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16
Q

What happens to the formulations when dimethylamine, formaldehyde, glacial acetic acid and indole is heated?

A

A clear solution forms with a rise in temperature

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17
Q

What temperature water bath is used to warm the dimethylamine, formaldehyde, glacial acetic acid and indole mix is heated?

A

35oC for 30 mins

18
Q

What is added to dimethylamine, formaldehyde, glacial acetic acid and indole mix after it is heated in a water bath?

A

Dilute sodium hydroxide solution OR NaOH

19
Q

How can the first lots of crystals form after adding NaOH?

A

Cooled down (ice bath) and the white precipitate forms

20
Q

How are the crystals separated from suspension?

A

Vacuum filtration after cooling in an ice bath

21
Q

What can be used to wash the crystals in vacuum filtration for the first time?

A

Cold water - wash twice

22
Q

How can the first crystals be treated to remove as much water as possible from the suspension?

A
  • Vacuum filtration

- Oven at 60oC

23
Q

What should be done after the first crystals have been dried, in order to purify them?

A

Recrystallisation

24
Q

What agents are used to recrystallise the gramine?

A
  • Acetone

- Petroleum ether

25
Q

In what way are the acetone and petroleum ether added to the crystals in the recrystallisation step?

A

Start with a boiling mixture of 40 mL petroleum ether and 5 mL acetone, then increase gradually the acetone content with 5 mL additions, until all the gramine has just dissolved in hot solvent.

26
Q

How should dimethylamine, formaldehyde and acetic acid be pipetted?

A

Use separate, graduated, glass pipettes from ‘stock bottles’ and do not rinse the pipettes with water or for reuse. Use the correct pipette:

1mL - Acetic acid

2mL - Formaldehyde

5mL - Dimethylamine

27
Q

How can the mass of the non-recrystallised and recrystallised powders be calculated?

A

Find the mass of a watch glass first, then transfer the solid to it, dry it in the oven (to constant mass or until freely flowing) and then obtain the mass

28
Q

Will the (gramine) crystals dissolve in pet ether?

A

The solid will not dissolve as it is not soluble

29
Q

What amount of acetone is expected to be used to make it soluble?

A

~15mL

30
Q

Why should the process allow for slow crystallisation?

A

Slower cooling produces better quality crystals - and more solid forms

31
Q

The expected mass of product does not look as if it has formed after the acetone AND pet ether has been added - why might this be?

A

Too much acetone may have been added

32
Q

The expected mass of product does not look as if it has formed after the acetone AND pet ether has been added - what can be done to recify this?

A

Take the flask back to hot plate and boil off half the volume of solvent. Cool in air and in an ice-bath again. More solid should form

33
Q

What can be used to wash a second lot of crystals during vacuum filtration?

A

Pet ether (<15mL)

34
Q

Why can water NOT be used to wash the second lot of crystals during vacuum filtration after recrystallisation?

A

Leads to poor quality crystals

35
Q

Why can acetone NOT be used to wash the second lot of crystals during vacuum filtration after recrystallisation?

A

They will dissolve

36
Q

What is donated from acetic acid that is attacked by the lone pair on formaldehyde?

A

H+

37
Q

What nucleophile attacks the carbon on the protonated formaldehyde?

A

N: on dimethylamine

38
Q

What ion is formed from the mechanism between formaldehyde and dimethylamine?

A

Iminium ion

39
Q

What synthesized ion is attacked by indole in the synthesis of gramine?

A

Iminium ion

40
Q

What other agent is necessary for the formation of Gramine?

  • Dimethylamine
  • Formaldehyde
  • Acetic acid
A
  • NaOH
41
Q

What other agent is necessary for the formation of Gramine?

  • Formaldehyde
  • Acetic acid
  • NaOH
A

Dimethylamine
Formaldehyde
- Acetic acid

42
Q

What is the end structure of Gramine?

A

draw it

james smith lab (4 decks)

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