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chemistry > Organic- Carbonyls, carb acids, esters > Flashcards

Organic- Carbonyls, carb acids, esters Flashcards

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1
Q

what are the reagents and conditions for the oxidation of an primary alcohol?

A

acidified potassium dichromate and sulfuric acid

heat and distillation

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2
Q

what does the oxidation of an primary alcohol form?

A

an aldehyde, which can undergo further oxidation via heat and reflux to form a carboxylic acid

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3
Q

what are the reagents and conditions for the oxidation of a secondary alcohol?

A

acidified potassium dichromate and sulfuric acid

heat and reflux

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4
Q

what does the oxidation of a secondary alcohol form?

A

a ketone, which cannot undergo further oxidation

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5
Q

why don’t ketones undergo further oxidation?

A

due to there being no H attached to the carbonyl carbon

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6
Q

do tertiary alcohols undergo oxidation?

A

no

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7
Q

why does propanal have a lower boiling point than propan-1-ol or propanoic acid?

A

propanal does not contain an OH bond, so does not involve hydrogen bonding, the strongest IMF. therefore less energy is required to break the bonds, as temporary induced dipole interactions are not as strong

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8
Q

what does tollen’s reagent/ammonical silver nitrate do?

A

differentiates between aldehydes and ketones/oxidises aldehydes to carboxylic acids

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9
Q

what are the reagents and conditions for the tollen’s test?

A

ammonical silver nitrate

gently warm in a boiling water bath

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10
Q

how can you tell if an aldehyde or ketone is present during the tollen’s test?

A

an aldehyde will form a silver mirror/black precipitate of silver

a ketone will not give a silver mirror

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11
Q

what is the half equation that you need to know for the tollen’s test and what does it show?

A

Ag+ (aq) + e- —-> Ag (s)

it shows the reduction of silver ions to silver

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12
Q

how would you reduce an aldehyde or ketone to an alcohol?

A

add NaBH4 (sodium borohydride) at room temperature, then dilute sulfuric acid

aldehydes will form primary alcohols, ketones will form secondary alcohols

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13
Q

how many hydrogens do you need in the equation for adding NaBH4 to balance and form the alcohols? *also need to know the nucleophilic addition mechanism

A

2[H]

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14
Q

how would you convert aldehydes and ketones to 2-hydroxynitriles? *need to know mechanism for this nucleophilic addition

A

add KCN, then dilute sulfuric acid at room temperature

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15
Q

why do we need to use KCN as well as HCN, which is what is written in the equation?

A

HCN is a poisonous gas and not a strong enough acid to give enough of the -CN nucleophile, so KCN is used with the conditions

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16
Q

what do aldehydes and unsymmetrical ketones form in the nucleophilic addition of HCN?

A

a mixture of enantiomers (a racemic mixture)

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17
Q

what are the reagents and conditions needed for the 2,4-DNP test?

A

2,4-DNP in methanol

room temperature

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18
Q

what is the 2,4-DNP test used for and what would the positive result look like?

A

to identify the presence of an aldehyde OR ketone

a crystalline orange precipitate

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19
Q

after the 2,4-DNP test, how would you distinguish between an aldehyde or ketone?

A

by looking at the melting point and matching them up on the data table

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20
Q

do carboxylic acids and esters react with 2,4-DNP?

A

no

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21
Q

explain how you would identify an aldehyde or ketone? (practical)

A

1) filter the impure orange solid to separate the solid precipitate from the solution
2) recrystalise the solid to produce a pure sample of crystals
3) measure and record the melting point of the purified 2,4-DNP and compare to the database of melting points to determine the specific carbonyl compound

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22
Q

CH3CH2CH2CHO, CH3CH2COCH3, CH3CH2CH2CH2OH

Describe a sequence of tests to identify which compound is which (6)

A

1) add each sample to a test tube and add 2,4-DNP to distinguish whether an aldehyde or ketone is present. if present, a crystalline orange precipitate will form. the sample with no precipitate is the alcohol.
2) add fresh samples of those remaining to 2 test tubes, add tollen’s reagent in a boiling water bath which will form a black precipitate of silver if an aldehyde is present. the sample without the precipitate is the ketone.

23
Q

explain the solubility of carboxylic acids

A

carboxylic acids tend to be soluble in water due to having a permanent dipole and hydrogen bonding, due to the OH bond present in the functional group. this makes them compatible with water, which also has hydrogen bonding.

24
Q

what are the products formed from carboxylic acid + metal?

A

a carboxylate salt + hydrogen

25
Q

what are the products formed from carboxylic acid + metal oxide?

A

a carboxylate salt + water

26
Q

what are the products formed from carboxylic acid + alkali?

A

a carboxylate salt + water

27
Q

what are the products formed from carboxylic acid + carbonate?

A

a carboxylate salt + water + carbon dioxide

28
Q

are carboxylic acids weak or strong?

A

weak

29
Q

what are the reagents and conditions needed for esterification?

A

carboxylic acid, alcohol, and concentrated sulfuric acid

heat and reflux (sometimes additional purification of the ester)

30
Q

what would you react in order to produce an ester?

A

a carboxylic acid and an alcohol

31
Q

what does reacting a carboxylic acid and an alcohol form?

A

an ester + water

32
Q

what type of reaction is esterification?

A

a condensation reaction

33
Q

how do you name an ester?

A

the first part comes from the alcohol, the second part comes from the carboxylic acid, which changes from -oic to -oate

34
Q

what are the uses of esters?

A

food flavourings and perfumes, due to having a smell (this can be used to identify an ester being produced)

also solvents, e.g. in nail polish, or plasticizers

35
Q

what molecules do acid anhydrides consist of?

A

2 acid molecules which have lost a water molecule

36
Q

if both R groups were methyl, what would the acid anhydride be?

A

ethanoic anhydride

37
Q

if both R groups were ethyl, what would the acid anhydride be?

A

propanoic anhydride

38
Q

what are the reagents and conditions needed to synthesise esters from acid anhydrides and what are the products?

A

acid anhydride and alcohol
room temp (faster if gently warmed)

carboxylic acid and ester

39
Q

what is the advantage of using acid anhydrides?

A

they are more reactive than carboxylic acids, so there is no equilibrium, so yield increases

40
Q

what is the famous reaction of ethanoic anhydride?

A

forming aspirin

41
Q

what are the reagents needed for the ester hydrolysis under acidic conditions?

A

ester and concentrated sulfuric acid

heat and reflux

42
Q

what are the products of ester hydrolysis under acidic conditions?

A

a carboxylic acid and alcohol

43
Q

what are the reagents and conditions needed for the ester hydrolysis under alkaline conditions?

A

ester and concentrated sodium hydroxide

heat and reflux

44
Q

what are the products of ester hydrolysis under alkaline conditions?

A

a carboxylate salt (which can be acidified to a carboxylic acid) and alcohol

45
Q

what are the reagents and conditions needed for the formation of acyl chlorides from carboxylic acids?

A

carboxylic acid and SOCl2

heat and reflux

46
Q

how does the name change for acyl chlorides?

A

the -e of the alkane changes to -oyl chloride

47
Q

what does acyl chloride + water make?

A

carboxylic acid + HCl

48
Q

what does acyl chloride + alcohol make?

A

ester + HCl

49
Q

what does acyl chloride + ammonia make?

A

primary amide + HCl

49
Q

what does acyl chloride + primary amine make?

A

N-substituted amide + Hcl

50
Q

what are the reagents and conditions needed to form products from acyl chlorides?

A

the reagent (alcohol etc)

room temperature

51
Q

what are the advantages of using ethanoic anhydride over ethanoyl chloride in aspirin manufacture?

A

-no HCl as a side product (only impurity is ethanoic acid which is easy to remove)
-cheaper

52
Q

how to name a primary amide from an acyl chloride?

A

remove the -oyl chloride and replace with -amide

chemistry (7 decks)

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