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PHA111 > Functional Group Chemistry > Flashcards

Functional Group Chemistry Flashcards

1
Q

what does ADME stand for?

A

absorption, distribution, metabolism, excretion

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2
Q

name 4 features of a nucleophile

A
  • nucleus-loving
  • electron rich
  • negative charge/lone pair of electrons
  • double bonds
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3
Q

name 3 features of an electrophile

A
  • electron-loving
  • electron poor
  • positive charge
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4
Q

what are leaving groups?

A

terminology used for ions or neutral molecules that are displaced from a reactant as part of a mechanistic sequence

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5
Q

how are leaving groups formed?

A

a consequence of a nucleophile attacking an electrophile, where the electrophile carries a suitable leaving group

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6
Q

what makes a good leaving group?

A

those that form stable ions or neutral molecules after they leave the substrate

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7
Q

what is heterolysis?

A

bond breaks such that both of the electrons stay with one of the atoms

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8
Q

what is homolysis?

A

bond breaks so that each of the atoms retains one of the bonding electrons

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9
Q

what is standard free energy?

A

the different energy levels between the reactants and the products

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10
Q

what is activation energy?

A

the energy difference between the starting material and the transition state

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11
Q

what happens to the boiling point of alkanes as molecular weight increases?

A

it increases

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12
Q

what are the ONLY intermolecular forces present in alkanes?

A

weak London forces

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13
Q

are alkanes reactive or unreactive?

A

unreactive

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14
Q

what do alkanes produce during combustion?

A

CO2, H2O and heat

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15
Q

during halogenation, what do alkanes react with?

A

chlorine and bromine

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16
Q

when can halogenation occur?

A
  • at high temperatures

- in the presence of high energy light

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17
Q

what mechanism is halogenation?

A

radical mechanism

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18
Q

what are the three steps in a radical mechanism?

A
  • initiation
  • propagation
  • termination
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19
Q

what happens during initiation?

A
  • formation of radical

- light induced formation of chlorine radicals through homolysis from neutral chlorine

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20
Q

what happens during propagation?

A
  • one radical is used to generate another radical

- the chlorine radical can now abstract a hydrogen from another neutral molecule CH4 producing a methyl radical

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21
Q

what happens during termination?

A

-the combination of two radicals to produce a neutral species

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22
Q

what is hyperconjugation, how does it occur and what does it result in?

A

it is a stabilising interaction that occurs when the electrons in a o bond interact with an adjacent unfilled p orbital or pi orbital. it results in an extended molecular orbital that increases the stability of the system

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23
Q

what two radicals are more stable than expected and why?

A

benzyl and allyl due to resonance:

  • delocalisation of electrons
  • partial radicals residing over several atoms instead of just one
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24
Q

what is resonance used to describe?

A

electron charge and delocalisation

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25
Q

why are cis isomers less stable than trans isomers?

A

there is a strain between the two larger substituents on the same side of the double bond

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26
Q

are alkenes more or less reactive than alkanes?

A

much more reactive

27
Q

how are alkanes prepared? (3)

A
  • cracking
  • dehydrohalogenation
  • dehydration
28
Q

what type of reactions do alkenes undergo?

A

electrophilic addition

29
Q

why do alkenes undergo electrophilic addition? (3)

A
  • electrons in pi bond are accessible reactants
  • they are nucleophilic and react with electrophiles
  • electrons move from bond to electrophile
30
Q

what are the two types of addition reactions in an alkene and what do they involve?

A
  • homolytic (involves radicals)

- heterolytic (involves cations)

31
Q

what is the rate limiting step in the addition of HX to an alkene?

A

carbocation formation

32
Q

why is the stability of the carbocation important?

A

it controls the overall outcome of the reaction

33
Q

what is Markovnikov’s rule?

A

in an electrophilic addition to an alkene, the electrophile adds in such a way as to form the most stable intermediate

34
Q

what occurs in order to keep markovnikov’s rule?

A

-reaction proceeds via the most stable carbocation
-the electrophile adds to the sp2 carbon in the double bond that is the most substituted
-

35
Q

what molecules add to alkenes to form markovnikov products in the absence of light or peroxide?

A

HCl, HBr, HI

36
Q

what happens in a regioselective reaction?

A

one constitutional isomer is the major, or the only, product

37
Q

what is determined by the stability of the intermediate carbocation?

A

the outcome of the product

38
Q

are alkyl groups electron donating or withdrawing?

A

electron donating (weakly)

39
Q

what is hyperconjugation

A

stabilising interaction between a p orbital and C-H o bonds on neighbouring carbons

40
Q

do alkyl groups increase or decrease the concentration of positive charge on C+

A

decrease

41
Q

in alcohols, what happens to the acidity as alkyl substitution increases? and what is this known as?

A

it decreases, known as a positive inductive effect

42
Q

in alcohols, what happens to the acidity when the number of halogen substituents increases? and what is it known as?

A

it also increases, known as a negative inductive effect

43
Q

how is ethanol produced?

A

industrially produced by fermentation of starch and grains

44
Q

what is the toxic dose of methanol?

A

100mL

45
Q

what is the toxic dose of ethanol?

A

200mL

46
Q

how are more complex alcohols prepared? (3 main methods)

A
  • hydration of alkenes
  • hydrolysis of alkyl halides (nucleophilic sub reactions)
  • reduction of carbonyl compounds
47
Q

what 2 substances can reduce aldehydes and ketones? how do they work?

A
  • sodium borohydride NaBH4
  • lithium aluminium hydride LiAlH4
  • they act as sources of hydride and as additions of H-H across C=O
48
Q

what is the only substance esters can be reduced by?

A

LiAlH4

49
Q

what is alkoxideformation?

A

reaction of alcohol with sodium metal

50
Q

are high oxidation state metal salts good oxidising agents? why?

A

yes, as they are soluble in water

51
Q

how does biological oxidation of alcohols occur in the body?

A

carried out by enzymes using NAD+ as a coenzyme

52
Q

what is the function of alcohol dehydrogenase?

A

converts alcohol to aldehyde

53
Q

what is the function of aldehyde dehydrogenase?

A

converts aldehyde to acid

54
Q

what can the process of biological oxidation be inhibited by?

A

disulfiram

55
Q

how can haloalkanes be used as anaesthetics?

A

accumulate in lipid membrane of nerve cells and interfere with transmission of nerve impulses

56
Q

does an alkane or haloalkane have higher BP?

A

haloalkane

57
Q

why do haloalkanes have higher BP than alkanes?

A

the greater polarisability of C-X bond

58
Q

how can haloalkanes be prepared? (4)

A
  • free radical substitution of alkanes
  • electrophilic addition (H-X) to alkenes
  • halogenation of alkenes or alkynes
  • halogenation of alcohols
59
Q

what happens to the rate of reaction with a given nucleophile when the size of the haloalkane increases?

A

decreases

60
Q

what is the name of a one step Sn2 reaction mechanism?

A

concerted

61
Q

what is nucleophilicity?

A

a measure of how readily a compound is able to react with an electron-deficient atom

62
Q

what is polarisability?

A

a measure of how well a nucleophile can encroach on the orbital used for bonding in the electrophile

63
Q

what is basicity? and how is it measured?

A

a measure of how well a compound is willing to donate a lone pair of electrons to a proton. it is measured using the acid dissociation constant Ka

PHA111 (9 decks)

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