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Chem 25 > Extraction > Flashcards

Extraction Flashcards

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1
Q

What is the purpose of extraction

A

to separate compounds based on solubility between two immiscible layers

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2
Q

what is the partition coefficient

A

it is a measure of how a substance distributes itself between two immiscible solvents at equilibrium

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3
Q

How can we efficiently extract solvents

A

it is more efficient to extract small volumes multiple times

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4
Q

for an extracting solvent, do we want a solvent with a higher or lower boiling point?

A

we want a lower boiling point so that it is easier to boil off

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5
Q

why is density important

A

the solvent with the lower density will be on top while the higher density solvent will be on the bottom

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6
Q

Why do we shake the separatory funnel thoroughly

A

it mixes the layers and pulls the organic compounds out of the aqueous layer

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7
Q

why do we need to vent the separatory funnel

A

as we shake it, vapor pressure can build u and explode

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8
Q

why do we wait before draining the separatory funnel

A

the layers need time to separate

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9
Q

why do we drain one layer from the bottom and one on top

A

to prevent contamination of the organic and aqueous layers

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10
Q

how do we tell what layer is aqueous

A

you can do a water test and see which layer the water disappears in

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11
Q

what does the organic layer contain

A

it contains neutral organic compounds

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12
Q

what do we do with the organic layer

A

we wash it with aqueous phases to remove excess aqueous molecules

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13
Q

what are the aqueous phases we use for washing

A

NaCl and NH4Cl

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14
Q

what are the drying agents we use and why do we use them

A

MgSo4, CaCl2, Na2SO4, K2CO3

they are drying agents that remove traces of water

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15
Q

why do we evaporate our organic layer after we are done

A

it removes excess solvent and leaves the compound of interest

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16
Q

what does the aqueous layer contain

A

it contains undesired inorganic compounds

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17
Q

what do we do with the aqueous layer once we obtain it

A

we can extract it multiple times to obtain the desired compiund

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18
Q

in an acid-base extraction, what do we do with the acqueous layer

A

we neutralize it and extract with a fresh organic solvent

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19
Q

Why do we do acid-base extractions

A

it allows us to separate two organic compounds by converting one into a water soluble salt

20
Q

what types of organic compounds can be made water soluble

A

acidic and basic compounds

21
Q

how can acidic compounds be made water soluble

A

they can be deprotonated with a basic wash

22
Q

what are the two acidic compounds we can make water soluble

A

phenols and carboxylic acids

23
Q

what are the basic compounds that we can make water soluble

A

amines

24
Q

how can basic compounds be made water soluble

A

they can be protonated with an acidic wash

25
Q

to deprotonate phenol, what is required

A

a strong base like hydroxide

26
Q

to deprotonate carboxylic acid, what is required

A

a weaker base like NaHCO3 (sodium bicarbonate)

27
Q

why do we have to be careful when using NaHCO3

A

it can decompose into gaseous CO2 and water

28
Q

what happens if we overshake/undershake a sep funnel

A

it we overshake it, it could cause an emulsion

if we undershake it, it may not establish equillibirum

29
Q

can you shake while its bubbling

A

lol no

30
Q

why do we use saturated NaCl in the organic layer and when do we do it?

A

it helps remove h20 before adding the drying agent

31
Q

why do we use a microwave

A

it is green chemistry, is faster, efficiently heats smaller samples, and has the microwave effect

32
Q

what is dipolar polarization? what is it best for

A

polar molecules

they will oscillate with the electric field and the collisions will produce heat

33
Q

what is conduction

A

ions or conductive molecules will oscillate with the electric field, causing polarization and resistance produces heat

it is very dangerous and should never be done with metals

34
Q

what was our extracting solvent

A

diethyl ether

35
Q

what did we use to isolate organic compounds from eachother

A

acid base extraction with sodium bicarbonate which deprotonated acetic acid and made it water soluble

36
Q

how would the hnmr for an ester differ than acetic acid

A

there would be a spilt peak around 4.1 ppm. For acetic acid, there would just be a singlet representing the methyl group

37
Q

how would butyl amine exist in Ph3 solution

A

it would be eprotonated and water soluble

38
Q

how would phenol exist in Ph3 solution

A

it would remain neutral

39
Q

how would cyclohexanol exist in Ph3 solution

A

it would remain neutral

40
Q

how would benzoic acid exist in Ph3 solution

A

it would remain neutral

41
Q

how would butyl amine exist in Ph12 solution

A

it would remain neutral

42
Q

how would phenol exist in Ph12 solution

A

it would be deprotonated

43
Q

how would cyclohexanol exist in Ph12 solution

A

it would remain neutral

44
Q

how would benzoic acid exist in Ph12 solution

A

it would be deprotonated

45
Q

what was the purpose of NaHCO3 extraction? what if it was omitted

A

it deprotonated the acetic acid and separated it from the organic product, without this we would have an impure mixture

46
Q

what method of microwave heating did we use

A

dipolar polarization, the compounds were btoh polar and oscillated in the magnetic field and causing collisions which heated the reaction

47
Q

why was this method more green

A

it allowed for less waste and heated things in faster time with less cleaning

Chem 25 (11 decks)

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