Carbonyl compounds Flashcards

1
Q

Structural formula of propanone

A

CH3COCH3

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2
Q

structural formula of propanal

A

CH3CH2CHO

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3
Q

aldehyde + ketone functional group

A

C=O (carbonyl)

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4
Q

what type of boiling point to aldehydes and ketones have

A

lower boiling point than equivalent alcohols

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5
Q

explain why aldehydes and ketones have a low boiling point

A
  • don’t have polar OH bond so can’t form hydrogen bonds with other aldehyde/ketone molecules
  • lower boiling point than equivalent alcohols which do form hydrogen bonds (strongest intermolecular force)
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6
Q

name the forces within aldehydes and ketones

A
  • london forces
  • permanent dipole- permanent dipole
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7
Q

describe solubility of aldehydes and ketones

A
  • soluble in water
  • lone pair of electrons on O of C=O
  • form hydrogen bonds with H atoms on water molecules
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8
Q

when are aldehydes and ketones not soluble

A
  • longer chained ketones + aldehydes cannot H bond with water
  • hydrocarbon chains disrupt H bonding between water molecules
  • london forces between aldehyde + ketone molecules (+) hydrogen bonding between water molecules stronger than hydrogen bonding between water + aldehyde/ketone
  • compound won’t dissolve
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9
Q

which compound can be oxidised further

A

aldehydes

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10
Q

describe test for aldehyde with Fehlings/benedicts solution

A
  • Fehlings: Copper(II) ions dissolved in sodium hydroxide
    -Benedicts: Copper(II) ions dissolved in sodium carbonate
    -positive result- Blue- Brick red precipitate
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11
Q

Fehlings/Benedicts reduction equation

A

Cu2+ (aq) + e- –> Cu+ (s)

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12
Q

Describe tollens reagent

A

colourless solution of silver nitrate dissolved in aqueous ammonia

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13
Q

describe test with Tollens reagent

A
  • heated in a test tube (water bath) with sample
  • ‘silver mirror’ forms
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14
Q

tollens reagent reduction equation

A

Ag(NH3)2(aq)+ + e- –> Ag(s) + 2NH3(aq)

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15
Q

what is acidified potassium dichromate

A

oxidising agent

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16
Q

describe test with acidified (VI) potassium dichromate

A
  • heat sample with acidified potassium dichromate
  • aldehyde oxidised- colour change orange to green
17
Q

reduction equation of dichromate ions

A

Cr2O72- + 14H+ + 6e- –> 2Cr3+ + 7H2O

18
Q

what is an oxidising agent represented with

A

[O]

19
Q

oxidation equation of ethanol

A

CH3CH2OH + [O] –> CH3CHO + H2O

20
Q

name a reducing agent

A

Lithium aluminium tetrahydride (LiAlH4)

21
Q

what is a reducing agent represented with

A

[H]

22
Q

conditions for reduction of carbonyls

A

LiAlH4 in dry ether

23
Q

reduction equation of ethanal

A

CH3CHO + 2[H] –> CH3CH2OH

23
Q

reduction equation of propanone

A

CH3COCH3 + 2[H] –> CH3CH(OH)CH3

24
Q

Give the name for Brady’s reagent

A

2-4 DNPH

25
Q

what tests for a carbonyl group and what is the positive result

A
  • 2-4 DNPH
  • orange precipitate
26
Q

what is a methyl carbonyl and what is used to test for it

A
  • methyl group attached to C=O
  • iodine with heat and alkaline conditions
27
Q

positive result with test for methyl carbonyl

A

yellow precipitate (CH3I) + antiseptic smell

28
Q

conditions for formation of hydroxynitrile

A
  • HCN in presence of KCN
29
Q

what type of reaction forms hydroxynitriles

A

nucleophilic addition

30
Q

mechanism for reaction of carbonyl group + CN

A
31
Q

considerations with reaction with HCN

A

HCN highly toxic gas.
- reaction should be done in a lab, using solution of acidified potassium cyanide
- reaction in fume cupboard, wearing lab coat, gloves and safety glasses