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chemistry > colour by design > Flashcards

colour by design Flashcards

1
Q

bonds attaching dyes to fibres

A
  • hydrogen bonds
  • ionic bonds
  • covalent bonds
  • id-id bonds
  • pd-pd bonds
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2
Q

hydrogen bonds and attaching dyes to fibres

A
  • hydrogen bonds are formed between OH groups on fibre molecules and some dyes (like those with an NH2 group)
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3
Q

ionic bonds and attaching dyes to fibres

A
  • ionic bonds may bind a dye to a fibre
  • this is usually with an -NH3+ group on the fibre and -SO3- on the dye
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4
Q

covalent bonds and attaching dyes to fibres

A

covalent bonds are strongest and dyes which bond covalently have a functional group which will react with the fibre

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5
Q

id-id bonds and attaching dyes to fibres

A

id-id bond can also bind a dye to a fibre, usually only happens with small dye molecules since the bonds are very weak

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6
Q

pd-pd bonds and attaching dyes to fibres

A

pd-pd bonds can occur alongside hydrogen bonding when both the dye and fabric are polar (pd-pd is stronger than id-id)

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7
Q

functional groups of fibres

A

most fibres have functional groups which dyes bind to, such as
COOH
NH
CONH

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8
Q

what are fibre reactive dyes

A

Dyes which form covalent bonds with the fabric

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9
Q

what are colour fast dyes

A

dyes that don’t fade or wash out very easily due to strong bonds between the dye and fabric - (typically only ionic bonds and covalent bonds are strong enough to be colourfast)

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10
Q

chromophore definition

A

the part of a dye which gives it its colour (a chain of double and single bonds)

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11
Q

functional groups that affect dye solubility

A

ionic groups such as sulfonate (SO3 2-)

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12
Q

structure of fats and oils

A

mixed esters of propane-1,2,3-triol with varying degrees of saturation

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13
Q

triglyceride structure

A

one glycerol (propane-1,2,3-triol) constant and three fatty acid chains long chained carboxylic acids that vary

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14
Q

triglyceride formation

A

condensation reaction between glycerol and three fatty acids

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15
Q

triglyceride breaking
name of process and conditions

A

hydrolysis reaction, alkane solution (NaOH) and head under reflux conditions required

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16
Q

features of saturated fatty acids

A

contain only C-C single bonds
form straight chained molecules
pack closely together
high density
have higher bpt/mpt due to stronger intermolecular forces (id-id), heavier fats e.g. lard

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17
Q

features of unsaturated fatty acids

A

contain C=C double bonds
monounsaturated (one C=C) or polyunsaturated (many C=C bonds)
form kinks in structure
can’t pack as close together
lower density
weaker imf (id-id), so lower bpt/mpt

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18
Q

difference between fats and oils

A

oils have mpt below room temp
fats have mpt above room temp

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19
Q

features of arenes

A
  • cyclic hydrocarbons
  • planar shape
  • the pi electrons are stabilised by electron delocalisation
  • the number of pi electrons is 4n+2
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20
Q

phenyl group meaning

A

a benzene ring with one H replaced by another group

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21
Q

what is an aromatic compound

A

a molecule with a benzene ring

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22
Q

naming arenes

A

all groups attached to a benzene ring use the suffix ‘-benzene’
if benzene is not the main functional group, benzene is shown through the prefix ‘phenyl-‘

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23
Q

benzene and addition reactions

A

benzene does not easily take part in addition reactions because
- delocalised electrons stabilise benzene
-any disruption of electrons makes benzene unstable

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24
Q

benzene and substitution reactions

A

benzene will readily undergo substitution reactions with electrophiles
this is because the ring system is electron rich and will attack positive centres

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25
Q

electrophile definition

A

accepts a pair of electrons to make a covalent bond

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26
Q

position of delocalised ring in benzene

A

delocalised ring is above and below the plane of the molecule, made from p-orbitals

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27
Q

Hydrogenation evidence for the delocalised model of benzene

A
  • Hydrogenation is a reaction where H2 is added to an alkene to remove its double bonds
  • Cyclohexene is a six-carbon ring with one double bond
  • Its hydrogenation enthalpy change is −120kJmol-1
  • With the three double-bond structure of benzene, it would have a hydrogenation enthalpy change of 3× this
  • However, experimental evidence suggests that it’s much less exothermic than this
  • This is explained by the delocalised ring’s increased stability - more energy would be needed to hydrogenate it
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28
Q

polyfunctional molecules meaning

A

molecules that have multuple functional groups

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29
Q

naming polyfunctional molecules

A

the highest presedence functional group is the suffix and all other functional groups are listed in alphabetical order as a prefix

30
Q

nitration of benzene conditions

A

under 55C in monosubstitutions
over 55C in multiple substitutions
sulfuric acid
heat to reflux

31
Q

nitration of benzene mechanism steps

A
  1. generating electrophile
  2. formation of nitroarene
  3. reforming catalyst
32
Q

nitration of benzene electrophile

A

NO2 +
nitronium

33
Q

nitration of benzene overall reaction

A

benzene + nitric acid –> nitrobenzene + water

34
Q

sulfonation of benzene condition

A

heat under reflux

35
Q

sulfonation of benzene electrophile

36
Q

sulfonation of benzene overall reaction

A

benzene + sulfuric acid –> benzenesulfonic acid + water

37
Q

friedel-craft alkylation of benzene conditions

A

heat under reflux, halogen carrier (AlCl3), anhydrous

38
Q

friedel-craft alkylation of benzene electrophile

39
Q

friedel-craft alkylation of benzene overall reaction

A

benezene + chloroethane –> ethyl benzene + hydrochloric acid

40
Q

friedel-craft acylation of benzene conditions

A

heat under reflux, anhydrous, halogen carrier (AlCl3)

41
Q

friedel-craft acylation of benzene electrophile

42
Q

friedel-craft acylation of benzene overall reaction

A

benzene + acetyl chloride –> phenylethanone + hydrochloric acid

43
Q

halogenation of benzene conditions

A

room temperature, anhydrous, halogen carrier (AlCl3)

44
Q

halogenation of benzene electrophile

45
Q

halogenation of benzene overall reaction

A

benzene + chlorine –> chlorobenzene + hydrochloric acid

46
Q

what are azo dyes

A

dyes containing an azo group

47
Q

what is an azo functional group

48
Q

creating a diazonium compound

A
  1. formation of nitrous acid
    NaNO2 + HCl -> HNO2 + NaCl
  2. diazotisation reaction
    phenyl amine + nitrous acid -> benzenediazonium chloride
49
Q

creating an azo dye

A

diazonium salt + coupling agent (benzene ring with groups containing an OH or an NH2 group) -> an azo dye

50
Q

what are carbonyl compounds

A

compounds containing a C=O group with a polarised carbon=oxygen double bond
either ketones or aldehydes

51
Q

creating carboxylic acids from aldehydes

A

aldehyde –> carboxylic acid
heat under reflux
acidified potassium dichromate

52
Q

conditions of carbonyl reaction with fehling’s solution

A

warm (water bath, not flame as carbonyls are flammable)

53
Q

aldehyde reaction with fehling’s solution

A

aldehyde + fehling’s solution -> carboxylic acid + CuO2
blue –> brick red ppt

54
Q

ketone reaction with fehling’s solution

A

no reaction
remains blue

55
Q

conditions of carbonyl reaction with tollen’s reagent

56
Q

aldehyde reaction with tollen’s reagent

A

aldehyde + tollens reagent -> Ag(s) + RCOO- + H2O + 4NH3
forms shiny silver mirror ppt

57
Q

ketone reaction with tollens reagent

A

no reaction

58
Q

carbonyl + cyanide ion

A

O OH
ll l
- C- -> - C -
I
CN

59
Q

addition reaction meaning

A

two molecules join, breaking a double bond, making one product

60
Q

condensation reaction meaning

A

two molecules join, with a small molecule being lost (H2O, HCl)

61
Q

elimination reaction meaning

A

a functional group is lot, released as part of a small molecule

62
Q

substitution reaction meaning

A

a functional group on a molecule is replaced by another group

63
Q

oxidation reaction meaning

A

the loss of electrons

64
Q

reduction reaction meaning

A

the gain of electrons

65
Q

hydrolysis reaction meaning

A

water splits a molecule into two

66
Q

what causes colour

A
  • substances absorb photons
  • this provides energy for electrons to move from their ground state to an excited state
  • if this photon is visible light, that colour will be absorbed
  • because all other colours pass through the substance, it will appear the complementary colour of the absorbed colour
67
Q

what allows substances to appear coloured

A

conjugated systems

68
Q

what is a conjugated system

A
  • made up of alternating double and single bonds
  • electrons in pi bonds are able to become delocalised
  • can only occur when p-orbitals overlap on 3 or more adjacent atoms
69
Q

why are conjugated systems needed to show colour

A
  • double bonds have closer together energy levels than single covalent bonds
  • single bonds will absorb UV and not visible light and double bonds on their own will absorb low frequency UV
  • delocalisation occurring in conjugated system will decrease this frequency further, usually into the visible part of the spectrum
70
Q

gas liquid chromatography process

A
  • sample injected with syringe into a stream of carrier gas, an inert gas (e.g. He)
  • it enters an oven and turns into a gas, passing through a coiled column containing a very porous material and a liquid with a high boiling point (e.g. oil)
  • compounds with a high boiling point will spend a lot of time condensed in liquid form at the start of the column so they will spend a long time in the machine (will have a high retention time)

chemistry (10 decks)

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