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Chemistry A2 > Colour by Design - Carbonyl Reactions and Triesters > Flashcards

Colour by Design - Carbonyl Reactions and Triesters Flashcards

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1
Q

what is the product formed when aldehydes are oxidised with acidified dichromate?

A

carboxylic acids

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2
Q

what are the colour changes of the oxidation of aldehydes by acidified dichromate?

A

orange to green

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3
Q

what is the product formed when ketones are oxidised by acidified dichromate?

A

none - reaction doesn’t occur

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4
Q

what are the colour changes of oxidation of ketones by acidified dichromate

A

stays orange

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5
Q

what is Fehling’s solution?

A

a solution that tests whether a substance is an aldehyde or ketone

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6
Q

what is fehling’s solution made up of?

A

fehlings a -> aqueous copper ions

fehlings b -> alkaline solution with bidente ligand

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7
Q

describe how Fehling’s test is carried out

A

fehlings a and fehlings b warmed in water bath with sample

if aldehyde - transparent blue to brick red

if ketone - stays transparent blue

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8
Q

what is tollen’s reagent?

A

solution used to test for aldehydes/ketones

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9
Q

what is tollens reagent made up of?

A

silver oxide in ammonia

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10
Q

what is a positive result for tollens reagent?

A

test tube coated with silver mirror effect

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11
Q

draw an example reaction for esterification

A
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12
Q

what are the reaction conditions for esterification?

A

acid catalyst

heat under reflux

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13
Q

what is the difference between fats and oils?

A

fats - saturated, solid at rtp

oils - unsaturated, liquid at rtp

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14
Q

how are fats/oils formed?

A

when propane-1,2,3-triol (aka glycerol) reacts with long chain carboxylic acids in a condensation/esterification reaction

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15
Q

draw an example reaction of the formation of a triester/triglyceride

A
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16
Q

which part of triesters are carboxylic acid residues?

A

the long chains

17
Q

what are the properties of carboxylic acid residues in triesters?

A

usually unbranched hydrocarbon chains

usually an even number of carbon atoms

can be saturated or unsaturated

often not the same on each of the three ester links

18
Q

what is the significance of the carboxylic acid residues in triesters?

A

they determine the properties of the triester

19
Q

how do carboxylic acid residues determine the properties of triesters?

A

saturated = higher mtp, unsaturated = lower mtp

hydrophobic because they are long and unpolar

20
Q

why do unsaturated triesters have lower melting points?

A

the double bonds in the chains weakens the id-id bonds as they bend the chain so each chain is further apart from other chains

21
Q

what are the reaction conditions for the hydrolysis of triesters?

A

heat with conc NaOH

22
Q
A

Chemistry A2 (20 decks)

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