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chem > topic 6e: alcohols > Flashcards

topic 6e: alcohols Flashcards

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1
Q

primary alcohol

A

OH group bonded to a C bonded to only 1 other carbon atom

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2
Q

combustino of alcohols produces

A

carbon dioxide and water (complete)

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3
Q

halogenation

A

-OH is replaced bya halogen

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4
Q

how to holgenate to add chlorine

A

PCL5

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5
Q

ALCOHOLS REACTION WITH pcl5 product

A

POCl3 + HCl + substituted product

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6
Q

alcohols + PCl5 observation

A

steamy fumes (HCl gas)

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7
Q

chlorination of TERTIARY Alcohols

A
  • shake with HCl at room temp
  • forms compound + H2O
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8
Q

how to do iodination

A
  • red phosphorus + iodine
  • heat under reflux
  • 2P + 3I2 = 2PI3
  • alc + PI3 = halkane + h3po3
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9
Q

extfa product of iodination

A

H3PO3
(phosphoric acid)

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10
Q

how to dehydrate alcohol (elimination)

A

heat with a concentratred phosphoric acid
forms an alkene

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11
Q

dehydration (elimination) alcohol product

A

alkene + water

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12
Q

primary alcohols oxidise to …

A

ALDEHYDES (then to carboxylic acids)

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13
Q

seconadry alcohols oxidise to

A

KETONS

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14
Q

tertiary alcohols oxidise to

A

do not oxidise

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15
Q

usual oxidisiing agent

A

acidified potassium dichromate
K2Cr2O7 in DILUTE sulfuric acid

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16
Q

colour change oxidation of alcohols

A

orange (cr207)2- to green cr3+

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17
Q

cr2o7 2- colour

A

orange

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18
Q

cr 3+ colour

A

green

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19
Q

how to bromonate

A
  • potassium bromide + 50% sulfuric acid to form HBr. REFLUXXXXXXXXX
  • HBr + alc = halkane + h2o
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20
Q

reaction for potassium bromide + 50% conc sulfuric acid

A

2KBr+H2SO4 = K2SO4 + 2HBr

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21
Q

why does aldehyde need to be distilled off as soon as its formed

A

so it doesnt further oxidise to a carboxylic acid

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22
Q

heating under reflux

A
  • FULL OXIDATION eg carboxylic acid from primary, keton from secondary
  • products of oxidation remain in the reaction mixture; condense and then return to the heating flask
  • OPEN TOP!!!!!!
23
Q

DISTILLATION

A
  • PARTIAL oxidation eg aldehyde from primary alcohol
  • aldehyde is dsitilled off as its formed, (lower BP than alcohol)
  • collected in the receiver
24
Q

what to change to go from distillation to heat under reflux

A
  • open top condsner
  • vertical condenser
25
Q

why is x more soluble in ETHANOL than in WATER (2)

A
  • water has 2 h bonds/ molecule, ethanol only 1
  • h bonding in water stornger, requires more enegy to break
26
Q

why is yield low of the aldehyde when heating under reflux?

A
  • aldehyde is condesned
  • fully oxidises to a carboxylic acid
27
Q

purpose of anti bumping granules

A

-provides a surface for bubbles to form
- PREVENTS LARGE BUBBLES FROM FORMING

28
Q

why are SMALL alcohols soluble in water?

A
  • h bonds in water and in alcohols
  • of similar strenght
  • therefore h bonds form between the 2
29
Q

why are larger alcohols less soluble?

A
  • proporition of molecule that can H Bond is smaller
30
Q

ethanol from ethene (hydration of ethene)

A
  • ethene + steam
  • phosphoric (V) acid CATALYST
  • 300 degrees
  • 60-70 atmospheres
31
Q

ethanol can also be made by…

A

fermentation

32
Q

stereoisomers (2)

A
  • same structural formula
  • sifferent arrangement in space
33
Q

3 reasons for lower yeild

A
  • transfer losses (residue left on apparatus)
  • incomplete
  • side reactions
34
Q

why not use distillation to produce carboxylic acid

A
  • produces aldehyde
  • aldehyde will distil as soon as produced (before it turns into carboxylic acid)
35
Q

how to dry organic layer to preapre for distillation (2)

A
  • mix with drying agent eg anhydrous cacl2
  • leave until adding drying agent doesnt clump together
36
Q

how to improve distillation

A
  • add antibumbing granules
  • surface for bubbles to form
    -thermometer should be opposite entrance of condenser
  • collecting over wrong temperature range
  • ## add more ice water
37
Q

why add sodium hydrogen carbonate in the experiment?

A
  • react with HCl
  • to release CO2
38
Q

drying agent

A

sodium sulfate

39
Q

thermometer in experiment distillation must be

A

OPPOSITE TO OPENING OF CONDENSER

40
Q

in reactions, water enters the … of the condsner

A

BOTTOM

41
Q

conical flask in distillation must be …

A

open

42
Q

why no stopper in reflux?

A

so pressure doesnt build up

43
Q

why might you se brown vapour in bromonation?

A
  • Br2 gas produced
    -bromide ions have been oxidised by the acid
44
Q

why add HCl in the experiment?

A

remove any unreacted alcohol

45
Q

why open tap from time to time?

A

prevent build up of pressure (allow co2 to escape)

46
Q

explain why reaction is slow, then speeds up, then slows

A
  • slow due to repulsion
  • speeds up as mn2+ autocatalytic
  • slows down cos conc reactants decreases
47
Q

fermentation

A

glucoe = ethanol +co2

48
Q

fermentation conditions

A
  • anaerobic
  • yeast
  • 25-42 degrees c
49
Q

why can fermentation thought to be NOT carbon neutral

A

co2 emissions with vehicles for transporting

50
Q

how to turn a halogenoalkane into an alcohol

A
  • sodium hydroxide
  • aqueous
  • heat under reflux
    NUCLEOPHILIC SUBSTIUTION
51
Q

HYDRATION OF ETHENE name of mechanism

A

electrophilic addition

52
Q

WHY DONT TERTIARY OXIDISE

A
  • no H atom on central carbon
53
Q

why hydration of ethene over fermentation

A
  • fast reaction
  • purer product2
54
Q

alkene to diol

A

add acidified potassium 2 manganate

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