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Chemistry Unit 4 > Chem 4:5 - Compounds Containing the Carbonyl Group > Flashcards

Chem 4:5 - Compounds Containing the Carbonyl Group Flashcards

1
Q

Carbonyl Group Formula

A

> C=O

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2
Q

What are carbonyl groups present in ?

A

Aldehydes and Ketones

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3
Q

Aldehydes Formula

A

H
> C = O
R

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4
Q

Ketones Formula

A

R
> C = O
R

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5
Q

What can the R groups on the aldehydes and ketones be ?

A

Alkyl or Aryl

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6
Q

How do you name aldehydes?

A

1) Suffix = al
2) FG counted as par of the C chain.
3) No numbers needed because the ald group is always at the end.
4) CH2O = methanal

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7
Q

How do you name ketones?

A

1) suffix = one
2) C atom of FG part of the C chain.
3) C3H6O = propanone
4) No ketone with less than 3 C’s possible
5) no need to number C in prop or but because it can only be in one position.

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8
Q

What do you know about the reactivity of the carbonyl compounds?

A
  • Delta positive C makes it easy for nucleophilic reagents to attack.
  • Double bond means additions reactions possible due to the unsaturated carbonyl group.
  • Most common reaction in carbonyl groups = NUCLEOPHILIC ADDITION.
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9
Q

What can you use as the nucleophile for these nucleophilic addition reactions?

A

HCN/NaCN/KCN

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10
Q

Describe the mechanism for nucleophilic addition in words.

A

1) Arrow from Nu to C and arrow from double bond to O
2) C is now attached to Nu and O:-
Also arrow going from O to H+
3) Product is RR’CNuOH

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11
Q

What are the products of these nucleophilic addition reactions called?

A

Hydroxynitriles

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12
Q

What can the reaction produce?

A

A racemic mixture

  • forms an aldehyde and an unsymmetrical ketone
  • Because the CN ion may attack from above or below the C=O group.
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13
Q

What do these reactions do in terms of C chain length?

A

Increase it

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14
Q

What can aldehydes be oxidised to ?
what denotes the oxidising agent?
and what would the oxidising agent be?

A

Carboxylic acids
[o]
Potassium Dichromate (K2Cr2O7/H+) with dilute sulphuric acid.

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15
Q

Can ketones be oxidised to carboxylic acids? and why?

A

No

Because unlike Ald, a C-C bod must be broken.

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16
Q

What CAN oxidise ketones?

A

A stronger [o] can break ketones down into CO2 and H2O

This shortens the C chain

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17
Q

What tests can you use to distinguish aldehydes and ketones?

A

1) Fehlings test

2) Silver mirror test

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18
Q

What is Fehlings test?

A

Made from:
Fehlings A - Cu2+ (blue)
Fehlings B - alkali and complexing agent.

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19
Q

What is the silver mirror test?

A

Tollens Reagent

  • Complex of silver nitrate and ammonia
  • (Ag[NH3]2)
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20
Q

What occurs when an aldehyde is warmed with fehlings solution?

A

Brick red precipitate formed

  • of Cu(I) oxide
  • because copper oxide oxidises the aldehyde to a carbox acid.
  • Cu(II) reduced to Cu(I)
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21
Q

What happens when ketones are warmed with fehlings solution?

A

No reaction

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22
Q

What happens when an aldehyde is warmed with tollens reagent?

A

Metallic silver formed

  • Ald oxidised by tollens reagent
  • Ag+ reducd to metallic silver
  • Silver mirror formed on outside of test tube (spotlessly clean)
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23
Q

What is the reaction for an aldehyde and tollens reagent?

A

RCHO + [o]&raquo_space;> RCOOH

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24
Q

What happens when a ketone is warmed with tollens reagent?

A

No reaction

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25
Q

Many reducing agent can reduce Aldehydes and ketones to alcohols, what is an eg of a reducing agent and how does it work?

A

Sodium tetrahydridoborate (NaBH4)

  • In aqueous solution : H- ion formed.
  • This attacks the C=O (but not C=C because its repelled by e density)
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26
Q

Describe the mechanism of reducing an aldehyde and what is the only difference in reducing a ketone

A

1) Arrow from :H- to C and double bond to O
2) arrow from RHCHO:- to H+
3)RHCHOH molecule formed.
- PRIMARY ALC formed
In an ester - a secondary alcohol is formed.

27
Q

Formula of a carboxylic acid

A

COOH/CO2H

28
Q

What do you know about the FG’s and the properties of carboxylic acids

A

Has 2 FG’s - OH and C=O
This means they have different properties.
Eg the OH is more acidic in CA’s than alcohols.
Look at flashcard to see how to name CA

29
Q

Properties of CA’s

A
  • Form H-bonds with water
  • Up to butanoic acid are completely soluble in water
  • CA in solid state form H- bonds with eachother therefore MP is higher than alkanes of similar RM
30
Q

Identify the smells of ethanoic and butanoic acid.

A

Ethanoic acid = VINEGAR

Butanoic acid = RANCID BUTTER

31
Q

Formula Of esters

A

RCOOR’

32
Q

Compare Esters to CA’s

A

Esters derived from CA’s

H in the alc group of CA’s replaced by a hydrocarbon group (alkyl or aryl) therefore OH replaced by OR

33
Q

What are the properties of esters?

A

Volatile ad have pleasant smells
Look in txtbk for smells
look at flashcard for how to name esters

34
Q

What 3 things do you know about the reactivity of carboxylic acids?

A

1) delta positive carbon can be attacked by a nucleophile
2) Delta negative O can be attacked by charge species eg H+
3) Can act as an acid and lose a proton

35
Q

How are esters formed? and why is an equilibrium formed?

A

CA reacts with an alcohol
Sped up by strong acid catalyst.
Reversible reaction
The H from the OH group substituted for the hydrocarbon grp on the alcohol
read flashcard about hydrolysis of esters NOW

36
Q

Hydrolysis of esters

A

Delta positive carbon gets attacked by water acting as a weak nucleophile.
RCOOR’ +H2O&raquo_space;» RCOOH +R’OH
An equilibrium is produced because the reaction doesn’t go to completion.
An acid catalyst is used - speeds up rate at which eq reached but doesn’t change composition of elements

37
Q

How do you name carboxylic acids?

A

1) CA group counted as part of the carbon chain
2) CA Carbon is counted as the 1st C if it has any side chains
Eg. HCOOH - Methanoic acid

38
Q

How do you name esters?

A

1) Based on the parent acid therefore the name always begins with the alkyl/aryl group that has replaced the hydrogen from the carboxylic acid
2) Eg CH3COOCH3 =Methyl (from he alkyl/aryl group) Ethanoate because theres 2 carbons attatched to the CH3.

39
Q

How does a carboxylic acid act as a proton? And what do you know about the resulting ion?

A
  • H from OH group is lost to form a Carboxylate ion : RCOO-
  • Therefore now the negative charge is shared over the whole molecule
  • The delocalisation makes the ion very stable.
40
Q

Carboxylic acids are weak acids, therefore the equilibrium lies well to the left. But what are they still able to do ?

A

React with sodium hydrogen carbonate and release CO2. This distinguishes them from other organic groups that contain OH (eg Alcohols)

41
Q

What is the equation when ethanoic acid (carboxylic acid) reacts with sodium hydrogen carbonate?

A

CH3COOH + NaHCO3&raquo_space;»> CH3COONa + H2O + CO2

42
Q

Carboxylic acids are proton donors therefore they act as acids, how does this work?

A

-They form ionic salts with reactive metals/alkalis/metal oxides/metal carbonates
-Salts formed have the general name CARBOXYLATES.
Eg methanoic acid = methanoates
ethanoic acid = ethanoates etc

43
Q

What would the equation be between ethanoic acid and sodium hydroxide?

A

CH3COOH + NaOH&raquo_space;»» CH3COONa + H2O

44
Q

Hydrolysis of esters part 2

A
  • Esters can be hydrolysed at room temperature using strong acid catalyst.
  • Base can also be used as catalyst but produces the salt of the acid instead of the acid therefore the reaction goes to completion.
45
Q

2 equations showing hydrolysis of esters using strong acid catalyst and base

A

1) CH3COOCH3 + H2O&raquo_space;(reversible reaction)»(base catalyst - NaOH)»> CH3COONA + H2O

46
Q

Uses of esters

A
  • Animal and veg oils = Esters of propan 1,2,3 - triol (glycerol)
47
Q

What are the difference between fats and oils

?

A

Fats are solid at RT

Oils are liquid at RT

48
Q

What do fats and oils contain?

A

3 molecules of long chain CA’s - FATTY ACIDS

49
Q

What are oils and fats called?

A

Triglycerides

50
Q

Can fats and oils be hydrolysed in acid conditions? and if so, what are the products

A

yes, Fatty acids and glycerol

51
Q

Can fats and oils be hydrolysed with boiling with NaOH? if so, what are the products?

A

yes, Glycerol and a mixture of the salts that made up the esters

52
Q

What are the salts? And what makes the salt the type it is

A

soaps

the amount of fatty acid originally in the ester

53
Q

Properties of glycerol

A

3 O-H bonds therefore readily forms Hydrogen bonds

V soluble in water

54
Q

Uses of glycerol

A

Pharmecutical products (attracts waters therefore stops creams from drying)
Solvent in medicines and present in toothpaste
Solvent in food industry - food colouring
Plasticies

55
Q

Acyl Group?

A

RC(x2bondO) and something else

56
Q

What is acylation?

A

where an acyl group is introduced to another molecule

57
Q

all acid derivatives have an acyl group, what are 2 other acid derivatives?

A

Acid chlorides

acid anhydrides

58
Q

What are acid derivatives?

A

Derived from carboxylic acids
Formula RCOZ (Z can be a variety of groups)
if Z was CH3 then molec called - ETHANOYL

59
Q

Why is an acid derivative susceptible to nucleophilic attack?

A

Because it is polarised (delta C positive and negative delta O)
The Z is replaced by the nucleophile

60
Q

How readily this acid derivative nucleophilic substitution reaction is dependant on 3 factors, what are they??

A

1) magnitude of Delta positive carbon
2) how easily Z is lost
3) Hoe good the nucleophile is

61
Q

What 2 things make a good nucleophile

A

1) Lone pair to attack e- deficient carbon

2) Good at donating its lone pair

62
Q

What 4 molecules do acid cl and acid anhydrides react with ?

A

NH3 - ammonia
NH2R - Primary amine
H2O - Water
HOR- Alcohol

63
Q

What are the reactions of nucleophiles and acid anh/cl called?

A

Addition elimination reactions

64
Q

NOW READ FLASHCARDS FOR MECHANISMS

A

LOL

Chemistry Unit 4 (5 decks)

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