alcohols part 2 Flashcards

1
Q

what three important reactions do alcohols take part in

A
  • combustion
  • elimination
  • oxidation
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2
Q

what do alcohols burn in oxygen to form

A

co2 and water

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3
Q

why do alcohols combust more efficiently than alkanes

A

presence of O atom

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4
Q

what does an alcohol react to form in an elimination reaction

A

an alkene

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5
Q

elimination

A

a reaction in which an atom/group of atoms is removed from a reactant

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6
Q

why do elimination reactions of alcohol involve dehydration

A

water is eliminated

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7
Q

reagent elimination

A

conc h2so4

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8
Q

conditions elimination

A

heat

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9
Q

elimination of alchools what happens

A
  • oh group always removed
  • h atom from an adjacent c also removed
  • double bond forms between 2 c atoms
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10
Q

what can alcohols be oxidised by

A

oxidising agents such as acidifed potassium dichromate

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11
Q

what happens to acidified potassium dichromate when it acts as an oxidising agent

A

changes orange to green

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12
Q

half equation oxidation of alcohols

A

Cr2O72- + 14H+ + 6e- > 2Cr3+ + 7h2o

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13
Q

what is a primary alcohol oxidised to

A

an aldehyde and then to a carboxylic acid

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14
Q

general equation oxidation of primary alcohol

A

RCH2OH + {O} > RCOH + H2O

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15
Q

reagent and conditions oxidation primary

A

acidified potassium dichromate/ H+

gentle heat and distil

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16
Q

observation oxidation primary

A

orange to green

17
Q

why is the product of oxidation of primary alcohol likely to be an aldehyde

A

aldehyde will have lower boiling point than alcohol it was formed from
reaction hasn’t been given chance to go any further

18
Q

oxidation of ethanol symbol equation

A

CH3CH2OH + [O] > CH3CHO + H2O

19
Q

oxidation to carboxylic acid general equation

A

RCH2OH + 2[O] > RCOOH + H2O

20
Q

why is it 2[O] in symbol equation oxidation to carboxylic acid

A

alcohol being oxidised further

21
Q

conditions oxidation to carboxylic acid

A

cr2o72-/H+ heat and reflux

22
Q

why is product likely to be carboxylic acid

A
  • reaction given chance to go to completion

- no products able to condense and separate

23
Q

how can the carboxylic acid be removed from the reaction mixture when the reaction is complete

A

distillation

24
Q

oxidation of ethanol to carboxylic acid symbol equation

A

CH3CH2OH + 2[O] > CH3COOH H2O

25
what is a secondary alcohol oxidised to
a ketone
26
can ketones be oxidised
no
27
general equation oxidation secondary alcohols
RCOHR1 + [O] > RCOR1 + H2O
28
reagents and conditions oxidation secondary alcohol
acidified potassium dichromate | heat and relflux
29
symbol equation oxidation of propan-2-ol (seoncdary)
CH3CHOHCH3 + [O] > CH3COCH3 + H2O
30
Apparatus for oxidation to a carboxylic acid
Reflux
31
Apparatus oxidation of primary alcohols
Immediate distillation
32
How can the presence of an aldehyde functional group be confirmed
Using mild oxidising agents such as tollens or fehlings
33
Observations tollens reagent
Silver mirror seen
34
Organic product silver mirror test
Carboxylic acid
35
Observations fehlings solution
Blue solution to brick red pot
36
How can the presence of a carboxylic acid functional group be confirmed
Using sodium carbonate
37
Observations carboxylic acid and sodium carbonate
Effervescence
38
Organic product sodium carbonate and carboxylic acid
Carboxylate salt RCOO-Na+
39
General equation carboxylic acid and sodium carbonate
2RCOOH+ Na2CO3 > 2RCOONa + CO2 + H2O