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Chemistry :) > 6.1 Aromatic Compounds, Carbonyls and Acids (completed) > Flashcards

6.1 Aromatic Compounds, Carbonyls and Acids (completed) Flashcards

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1
Q

What is the carbonyl group?

A

Carbon oxygen double bond

C=O

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2
Q

What are examples of carbonyl compounds?

A

Aldehydes (from primary alcohols)

Ketones (from secondary alcohols)

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3
Q

How do you produce the carbonyl compounds?

A

Acidified potassium dichromate [O]

Aldehyde distill primary alcohol
Ketone reflux secondary alcohol
Carboxylic acid reflux primary alcohol

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4
Q

What is the test for aldehydes?

A 
Tollen’s reagant 
Heat in hot water bath
Silver compund is reduced to silver metal
Forms a silver mirror 
Aldehyde is reduced to carboxylic acid
Also NH4+ ions
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5
Q

What is the test for aldehydes and ketones?

A

2,4-DNPH Brady’s Reagent

Produce an orange precipitate

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6
Q

How can you find which carbonyl compound has tested positive with Brady’s reagent?

A

Purify and recrystallise and precipitate

Find its’s melting point and compare with known values

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7
Q

What is the reduction of aldehydes and ketones?

A

Nucleophilic addition to produce alcohols

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8
Q

How do you reduce aldehyde’s and ketones?

A 
With NaBH4 (sodium tetrahydridoborate) 
To produce a hydride ion H- with a lone pair
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9
Q

What is the first step in the mechanism of nucleophillic addition?

A

δ+ and δ- on C=O bond
Curly arrow from hydride ion lone pair to carbon
Curly arrow from C=O bond to oxygen

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10
Q

What is the second step in the mechanism of nucleophillic addition?

A

Lone pair and negative charge on oxygen
δ+ and δ- on H and O in water
Curly arrow from lone oxygen pair to hydrogen in H2O
Curly arrow from O-H bond to oxygen

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11
Q

What is the third step in the mechanism of nucleophillic addition?

A

Alcohol produced and OH- ion

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12
Q

What are the reagents and conditions needed to produce a nitrile from a carbonyl?

A

CN- ions
In dilute acid e.g. H2SO4
Nucleophilic addition

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13
Q

What does adding a cyanide ion do to the carbon chain?

A

Increases the length

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14
Q

What is the molecular formula of benzene?

A

C6H6

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15
Q

What was kekulé’s model for benzene?

A

Cyclic
Planar
Alternating double and single bonds

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16
Q

What were the problems with Kekulé’s model?

A

All the bonds are same length BUT in Kekulé’s model the C=C bonds will be shorter
Benzene does not behave like an alkene with C=C bonds as it does not easily undergo addition reactions
The enthalpy is not as exothermic as predicted (it’s too stable)

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17
Q

What is the updated benzene model?

A

π electrons are in delocalised rings of overlapping p orbitals above and below the carbon ring
Planar ring
120° bond angle
Carbon bonds are all the same length

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18
Q

Describe the mechanism for electrophilic substitution

A

Curly arrow from benzene ring to Electrophile (E+)

Half ring with + inside
H and E bonded to carbon ring
Curly arrow from H bond to +

Electrophile bonded to carbon ring
H+ as other product

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19
Q

What are the reagants of the nitration of benzene?

A

Conc. nitric acid
Conc. sulphuric acid (catalyst)
Reflux
55°c

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20
Q

What is the nitration of benzene used for?

A

Explosives, dyes

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21
Q

How is sulphuric acid regenerated as a catalyst in the nitration of benzene?

A

H2SO4 + HNO3 → HSO4- + NO2+ + H2O
NO2+ is electrophile which generates H+ inmechanism
H+ + HSO4- → H2SO4

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22
Q

What happens if you added bromine water to benzene?

A

Nothing happens

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23
Q

How does the halogenation of benzene occur?

A

By using a halogen and a halogen carrier catalyst
e.g. Fe, FeCl3, AlCl3
Reflux

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24
Q

How does the halogen carrier catalyst produce a halogen electrophile?
(use chlorine and AlCl3)

A

Cl2 + AlCl3 → AlCl4- + Cl+
it’s regenerated so is a catalyst
AlCl4- + H+ → AlCl3 + HCl

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25
What are the two types of Friedal Crafts Reactions?
Alkylation - substitution with an alkane R e.g. CH3Cl | Acylation - substitution with a carbonyl R-CO e.g. CH3COCl
26
What are the Friedal Crafts Reactions?
Formation of a C-C bond to an aromatic ring
27
What are the reagants and conditions needed for alkylation?
Alkyl Chloride - RCl Halogen carrier catalyst e.g. AlCl3 Anhydrous conditions Electrophilic Substitution Mechanism
28
What are the reagants and conditions needed for acylation?
C=O RCOCl Halogen carrier catalyst e.g. AlCl3 Anhydrous conditions Electrophilic Substitution Mechanism
29
Why does the hydrogenation of benzene have a higher value?
It's resistant to hydrogenation becuase it destroys the stable delocalised electron system giving it a high activation energy
30
What is phenol?
C6H5OH | A very weak acid with an OH group attached directly to the benzene ring
31
Why is phenol solid at room temperature?
It can form hydrogen bonds which require more energy to break It's an almost colourless cyrstaline solid
32
What does phenol react with?
Metals Hydroxide NOT carbonates (it's too weak an acid)
33
Why can phenol react with bromine without a halogen carrier?
The lone electron pair on OH is drawn into the deloclaised benzene ring increases the electron density of the ring activating it able to induce a dipole on Bromine
34
What is the reaction of phenol with sodium and sodium hydroxide?
``` Produces Sodium Phenoxide C6H5O-Na+ and H2O (NaOH) or H2 (2Na) ```
35
How do 2- 4- directing groups affect the reactivity of the ring when activating it?
Increase it by donating an electron onto the ring
36
How do 3- directing groups affect the reactivity of the ring when activating it?
Decrease it by withdrawing an electron from the ring
37
What are examples of 2- 4- directing groups?
OH | NH2
38
What are examples of 3- directing groups?
NO2
39
What are the uses of phenols?
TCP Adhesives Compact discs
40
What are nitriles used to make?
Amines
41
What is the addition of HCN to a carbonyl?
Nucleophilic addition
42
What is the functional group of carboxylic acids?
-COOH
43
Are carboxylic acids soluble and if so why?
Yes, they have hydrogen bonding
44
How does the solubility change as the chain length increases?
Decreases as a result of the increasing nonpolar chain which can’t interact with water molecules
45
What is the reaction of a metal and a carboxylic acid?
Salt e.g. magnesium ethanoate | Hydrogen 
46
What is the reaction of a hydroxide and a carboxylic acid?
Salt e.g. potassium propanoate | Water
47
What is the reaction of a carbonate and a carboxylic acid?
Salt e.g. Calcium methanoate Water CO2
48
What are the uses of esters?
Perfumes, flavourings, essential oils, adhesives
49
What is the conditions needed for esterification?
Strong catalyst | e.g. concentrated sulphuric acid
50
What is the reaction of an acid and alcohol?
RCOOH + R'OH → RCOOR' + H2O
51
Name these esters 1) CH3CH2COOCH3 2) HCOOCH2CH3 3) CH3OOCCH3
1) Methyl Propanoate 2) Ethyl Methanoate 3) Methyl Ethanoate
52
What is the reaction between an acid anhydride and an alcohol?
Acid anhydride + alcohol → Ester + carboxylic acid
53
How can Esters be hydrolysed?
Under acidic or alkaline conditions | Reflux
54
What is hydrolysis for esters with acidic conditions?
Produces a carboxylic acid and alcohol Requires reflux Same conditions as esterification so dynamic equilibrium is formed
55
What is hydrolysis for esters with alkaline conditions?
Produces a salt E.g. sodium ethanoate | And alcohol
56
What is the acyl group?
RCOR’
57
What is an acyl chloride?
RCOCl
58
How do you produce an acyl chloride?
Carboxylic acid + Thionyl chloride (SOCl2) → Acyl Chloride + SO2 + H2O
59
What is the reaction of an acyl chloride and water?
Produces carboxylic acid and HCl
60
What do acyl chlorides react with?
Nucleophiles
61
What is the reaction of an acyl chloride and alcohol?
Ester + HCl
62
What is the reaction of an acyl chloride and ammonia?
Primary amide
63
What is the reaction of an acyl chloride and primary amide? 
Secondary amide

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