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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
electrophile definition
accepts a pair of electrons to make a covalent bond
26
position of delocalised ring in benzene
delocalised ring is above and below the plane of the molecule, made from p-orbitals
27
Hydrogenation evidence for the delocalised model of benzene
- 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
28
polyfunctional molecules meaning
molecules that have multuple functional groups
29
naming polyfunctional molecules
the highest presedence functional group is the suffix and all other functional groups are listed in alphabetical order as a prefix
30
nitration of benzene conditions
under 55C in monosubstitutions over 55C in multiple substitutions sulfuric acid heat to reflux
31
nitration of benzene mechanism steps
1. generating electrophile 2. formation of nitroarene 3. reforming catalyst
32
nitration of benzene electrophile
NO2 + nitronium
33
nitration of benzene overall reaction
benzene + nitric acid --> nitrobenzene + water
34
sulfonation of benzene condition
heat under reflux
35
sulfonation of benzene electrophile
SO3
36
sulfonation of benzene overall reaction
benzene + sulfuric acid --> benzenesulfonic acid + water
37
friedel-craft alkylation of benzene conditions
heat under reflux, halogen carrier (AlCl3), anhydrous
38
friedel-craft alkylation of benzene electrophile
CH3CH2+
39
friedel-craft alkylation of benzene overall reaction
benezene + chloroethane --> ethyl benzene + hydrochloric acid
40
friedel-craft acylation of benzene conditions
heat under reflux, anhydrous, halogen carrier (AlCl3)
41
friedel-craft acylation of benzene electrophile
+COCH3
42
friedel-craft acylation of benzene overall reaction
benzene + acetyl chloride --> phenylethanone + hydrochloric acid
43
halogenation of benzene conditions
room temperature, anhydrous, halogen carrier (AlCl3)
44
halogenation of benzene electrophile
Cl+
45
halogenation of benzene overall reaction
benzene + chlorine --> chlorobenzene + hydrochloric acid
46
what are azo dyes
dyes containing an azo group
47
what is an azo functional group
R-N=N-R
48
creating a diazonium compound
1. formation of nitrous acid NaNO2 + HCl -> HNO2 + NaCl 2. diazotisation reaction phenyl amine + nitrous acid -> benzenediazonium chloride
49
creating an azo dye
diazonium salt + coupling agent (benzene ring with groups containing an OH or an NH2 group) -> an azo dye
50
what are carbonyl compounds
compounds containing a C=O group with a polarised carbon=oxygen double bond either ketones or aldehydes
51
creating carboxylic acids from aldehydes
aldehyde --> carboxylic acid heat under reflux acidified potassium dichromate
52
conditions of carbonyl reaction with fehling's solution
warm (water bath, not flame as carbonyls are flammable)
53
aldehyde reaction with fehling's solution
aldehyde + fehling's solution -> carboxylic acid + CuO2 blue --> brick red ppt
54
ketone reaction with fehling's solution
no reaction remains blue
55
conditions of carbonyl reaction with tollen's reagent
warm
56
aldehyde reaction with tollen's reagent
aldehyde + tollens reagent -> Ag(s) + RCOO- + H2O + 4NH3 forms shiny silver mirror ppt
57
ketone reaction with tollens reagent
no reaction
58
carbonyl + cyanide ion
O OH ll l - C- -> - C - I CN
59
addition reaction meaning
two molecules join, breaking a double bond, making one product
60
condensation reaction meaning
two molecules join, with a small molecule being lost (H2O, HCl)
61
elimination reaction meaning
a functional group is lot, released as part of a small molecule
62
substitution reaction meaning
a functional group on a molecule is replaced by another group
63
oxidation reaction meaning
the loss of electrons
64
reduction reaction meaning
the gain of electrons
65
hydrolysis reaction meaning
water splits a molecule into two
66
what causes colour
- 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
what allows substances to appear coloured
conjugated systems
68
what is a conjugated system
- 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
why are conjugated systems needed to show colour
- 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
gas liquid chromatography process
- 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 (12 decks)

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