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GAMSAT Chemistry organic reaction pathways > 7. Aldehydes & Ketones > Flashcards

7. Aldehydes & Ketones Flashcards

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1
Q

how can aldehydes be prepared - what reagents and reactants are needed

A

via PCC and primary alcohol

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2
Q

what are the 2 ways that ketones can be prepared

A

oxidation of alcohol

friedel craft acylation of aromatic ring

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3
Q

what reagents and reactants are needed when preparing ketones from alcohols via oxidation

A

H2CrO4 and secondary alcohol

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4
Q

what reagents and reactants are needed when preparing ketones via friedel craft acylation of aromatic ring

A

RXC=O/AlX3

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5
Q

what is tollens test in terms of reagents and reactants it involves and what it distinguishes between plus its observations

A

Ag(NH3)2+/heat

Ag+ ions reduced to form silver mirror for aldehydes and it produces COOH

no reaction or silver mirror for ketones - stays colourless

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6
Q

what is benedicts test in terms of reagents and reactants it involves and what it distinguishes between plus its observations

A

CuSO4/heat

blue to brick red colour change for aldehydes and COOH is produced

no colour change for ketone, stays blue

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7
Q

what is fehlings test in terms of reagents and reactants it involves and what it distinguishes between plus its observations

A

Cu2+ ions

blue to brick red precipitate for aldehydes

no reaction for ketones, stays blue

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8
Q

what reactants and reagents are needed when aldehydes are oxidised to COOH

A

H2CrO4

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9
Q

do ketones oxidise

A

no

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10
Q

what do you get when you oxidise aldehydes with H2CrO4

A

COOH

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11
Q

what reactants and reagents are needed when aldehydes and ketones are reduced to alcohols

A

NaBH4/H3O+

or

LiAlH4/H3O+

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12
Q

what do you get if you reduce an aldehyde with NaBH4/H3O+ or LiAlH4/H3O+

A

primary alcohol

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13
Q

what do you get if you reduce an ketone with NaBH4/H3O+ or LiAlH4/H3O+

A

secondary alcohol

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14
Q

what reagent and reactants do you need for aldehydes and ketones to react with grignards reagent

A

+RMgX

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15
Q

what do you get when methanal reacts with grignards reagent (+RMgX)

A

primary alcohol

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16
Q

what do you get when aldehyde reacts with grignards reagent (+RMgX)

A

secondary alcohol

17
Q

what do you get when aldehydes and ketones reacts cyanide followed by H3O+

  1. CN- 2. H3O+
A

COOH

18
Q

what reagents and reactants do you need to form a COOH from an aldehydes or ketone

A
  1. CN-
  2. H3O+
19
Q

what are the 2 steps involved in nucleophillic addition of aldehydes or ketones for strong nucleophile

A
  1. +Nu-
  2. +H+
20
Q

what are the 2 steps involved in nucleophillic addition of aldehydes or ketones for weak nucleophile

what other condition must be present for this to be possible

A
  1. +Nu-H
  2. -H+

must be where nucleophile is available in presence of an acid

21
Q

for nucleophillic addition of aldehydes or ketones what is the rate limiting step

A

formation of Nu-

22
Q

order these from fastest to slowest when udnergoing nucleophillic addition

aldehyde/methanal/ketone

why is there this difference in speed of reaction

A

methanal > aldehyde > ketone

due to increasing e- density with methanal progression to ketone (electronic and steric effects)

23
Q

what reagents or reactants are needed for aldehydes and ketones to undergo addition of oxygen nucleophile to produce a hemiacetal and acetal

A

to form hemiacetal = +1ROH/H+

to form acetal = +2ROH/H+

24
Q

what is produced when you react aldehydes or ketones with 1ROH/H+ and 2ROH/H+

A

1ROH/H+ = hemiacetal

2ROH/H+ = acetal

25
Q

what is an acetal

A

has 2 OR groups on it

26
Q

what is a hemiacetal

A

has -OR and -OH on it

27
Q

what reagents are needed to produce a imine or hemiaminal when an alcohol undergoes addition of nitrogen nucleophiles

A

NH3 or RNH2

+RNH2 = prod hemiaminal

-H2O = prod imine

28
Q

what is produced when you add NH3 or RNH2 to an alcohol

A

hemiaminal and then an imine

GAMSAT Chemistry organic reaction pathways (12 decks)

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