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CHEM 2150 > PRELIM 2 > Flashcards

PRELIM 2 Flashcards

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1
Q

list 12 principles of green chemistry

A

catalysis
atom economy
reduce derivatives
degradation
safer solvents / chemicals
hazardous chemical syntheses
accident prevention
renewable feedstock
prevention, pollution prevention
energy efficiency

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2
Q

atom economy

A

MW of atoms in desired products / MW of atoms in all reactants * 100

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3
Q

what does an atom economy of 54% mean

A

46% wasted

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4
Q

prevention

A

better than remediation, avoid generating waste than dealing with it

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5
Q

solution to prevention

A

design syntheses to prevent waste
avoid waste treatment or clean up
minimize waste amount

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6
Q

what is E-factor (environmental factor)

A

total mass of waste from process / mass of product = all - product / product

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7
Q

ideal E-factor

A

0, no waste produced (crude oil refinement)

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8
Q

example of e-factor (bulky and pharmaceuticals)

A

bulky (solvents): 1-5
pharma: ~4000 (lots of steps and need to be pure)

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9
Q

what is NOT waste

A

water (not contaminated)
recyclable solvents
evaporable solvents

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10
Q

when is water considered waste

A

contaminated (i.e. with DCM or halogenated solvents)

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11
Q

process mass intensity

A

mass of all materials used / mass of product (includes silica, catalysts, solvents, magnesium sulfate, etc)

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12
Q

describe strong acid

A

lots of dissociation into H+ and A-, big Ka, small pKa

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13
Q

when pH = pKa…

A

[acid] = [conjugate base]

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14
Q

when pH solution > pKa molecule…

A

molecule is mostly de-protonated (mostly conjugate base)
negative if acid
neutral if base

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15
Q

when pH solution < pKa molecule…

A

molecule is mostly protonated (mostly acid)
neutral if acid
positive if base

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16
Q

Ka formula for acid and base

A

acid: [A-][H+] / [AH]
base: [B][H+] / [BH+]

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17
Q

relation between partition coefficient and pH

A

increase pH = strong acid de-protonates = partition coefficient decreases (moves to aqueous layer)

charged molecules are more soluble in water

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18
Q

why is DCM bad

A

goes through nitrile gloves

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19
Q

what is in anacin

A

caffeine + aspirin + starch

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20
Q

esterification formula

A

alcohol + COOH –(acid catalyst)–> ester + water

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21
Q

why is H2SO4 or sulfuric acid bad catalyst

A

thick, leaves mess, gives chemical burns

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22
Q

advantages of p-toluene sulfonic acid

A

crystal, solid

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23
Q

how to purify esters

A

use extraction

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24
Q

how to drive esterification to products

A

need to push towards products because equilibrium constant is small (by putting in excess of reactant, we did COOH)

OR remove H20 with sieve

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25
Q

why is catalyst needed in esterification

A

protonate the carbonyl oxygen of the carboxylic acid, which makes it more electrophilic and more susceptible to nucleophilic attack by the alcohol

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26
Q

if you start with achiral and add stereocenter, what will product be

A

racemic

27
Q

what did walter do wrong in the show?

A

he started with achiral so that means he didnt make enantiomerically pure meth, he made racemic

28
Q

sudafed and meth

A

sudafed is correct stereoisomer (SS) of meth but it has an additional OH

29
Q

equation for specific optical rotation

A

specific optical rotation = observed angle of rotation / (c * l)
[alpha] = alpha_observed / (c * l)

30
Q

EE

A

EE = (observed specific optical rotation )/(maximum specific rotation)

31
Q

% isomer in excess

A

EE / 2 + 50%

32
Q

chiral switch

A

switching drug from racemic to chiral (enantiomerically pure)

33
Q

what does S proline do

A

enantiomerically pure catalyst; makes chiral transition state and therefore induces stereospecificity

34
Q

how can we increase yield and decrease cost

A

reduce number of steps

35
Q

thalidomide

A

racemic mixture marketed as safe anti-nausea drug for pregnant women but deformed babies were born because of (R)

36
Q

distillation

A

used to separate liquids that ARE miscible in each other

37
Q

fractional distillation

A

pure vapors condense on fractioning column then boil again to be even more pure

38
Q

how are boiling point and vapor pressure related

A

lower boiling point = higher vapor pressure

39
Q

vapor pressure of mixture

A

p_total = p_1 + p_2

40
Q

mole fraction

A

x = mol x / mol total

41
Q

when does boiling happen

A

P_vapor = P_atmosphere (on mountain, lower atm so lower bp so it takes longer to cook)

42
Q

Raoult’s Law

A

vapor pressures can be calculated from mole fraction
(P_a = P_a* X x_A)
vapor pressure of A = vapor pressure of pure A * mol fraction A

43
Q

bottom curve of distillation (bubble point)

A

BP of 2 component system; ends show BP of A and B

44
Q

top curve of distillation (dew point curve)

A

BP of a liquid with that vapor composition; temperature at which vapor condenses

45
Q

simple distillation

A

works well when BP different of solvents is big (>50 C)

46
Q

refractive index

A

measures purity of liquids by measuring bending of light as it passes from one medium to another

47
Q

refractive index equation

A

n_obs = n_A * x_A + n_B * x_B
measured RI = RI of A * mole fraction A + RI of B * mole fraction B

note x_A + x_B = 1

48
Q

why did we use pyridinium tribromide instead of Br2 only

A

solid, easier to weigh; bromine is liquid BC polarization and vapors are dangerous

49
Q

is it easier to synthesize racemic or enantiomerically pure

A

racemic

50
Q

Sepracor scam

A

create 1 enantiomer of racemic mixture and sell back to company

51
Q

positive deviation from Raoults law

A
  • VP is greater than expected
  • cannot separate components completely because you cannot change composition of the vapor (boils both at same temperature)
  • BP azeotrope is less than both pure components
52
Q

negative deviations from Raoults Law

A
  • VP is lower than expected
  • can separate components depending on compositions
  • BP azeotrope is more than both pure components
53
Q

azetrope

A

constant boiling temperature, vapor and liquid have same composition

54
Q

do safer drugs have wider or narrower therapeutic windows

A

wider

55
Q

danger of narrow window

A

small increase in dose may produce toxic effects, higher risk of overdose

56
Q

lethal dose 50%

A

dose at which compound kills half the test animals

57
Q

effective dose 50

A

dose required for 50% of subjects to experience given effect

58
Q

toxic dose 50

A

dose where 50% experience toxic effect

59
Q

therapeutic index

A

LD50 / ED50 for animals
TD50 / ED50 for humans

60
Q

formaldehyde

A

carcinogen, causes cancers like leukemia, in vaccines (small amounts)

61
Q

aspartame

A

artificial sweetener that breaks down into formaldehyde inside the body

62
Q

are esters ionizable

A

no

63
Q

large esters low VP (smell)

A

never reaches nose

64
Q

purpose of bicarbonate wash

A

neutralize any remaining acidic components (carboxylic acid which was excess) in the organic layer

CHEM 2150 (2 decks)

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