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stay awhile, don't deny the violet chemistry > 18 - Organic Chemistry III > Flashcards

18 - Organic Chemistry III Flashcards

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1
Q

What are aromatic compounds?

A

Compounds containing a hydrocarbon ring containing delocalised electrons

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2
Q

What are aliphatic compounds?

A

Ones which do not have a hydrocarbon ring with delocatised electrons

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3
Q

What is benzene described as?

A

An arene

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4
Q

What are the physical properties of benzene?

A

A colourless liquid
Boiling temperature of 80 degrees
Insoluble in water

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5
Q

What is the molecular formula of benzene?

A

C6H6

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6
Q

What is the Kekule structure of benzene?

A

Alternating double and single bonds in a cyclic structure with a ring of hydrogen around it

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7
Q

How does bromine water disprove the Kekule structure?

A

If benzene contained three C=C bonds, it would readily decolourise bromine water, but it does not, suggesting there are no double bonds

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8
Q

How do the isomers of dibromobenzene disprove the Kekule structure?

A

If the Kekule structure is correct, there would be four isomers of dibromobenzene, however only three are known to exist as there are no C=C bonds

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9
Q

How do bond lengths disprove the Kekule structure?

A

C-C bonds and C=C bonds are different lengths, but in benzene the bonds lengths are all the same, so there cannot be different types of bonds in the molecule

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10
Q

How do enthalpy changes of hydrogenation disprove the Kekule structure?

A

The actual enthalpy change of hydrogenation of benzene differs from the theoretical value for if it had C=C double bonds

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11
Q

What are the four factors which disprove the Kekule structure?

A

Bromine water
Isomers of dibromobenzene
Bond lengths
Enthalpy change of hydrogenation

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12
Q

In the actual structure of benzene how are the electrons aranged?

A

In two delocalised rings, one above and one above the Carbon ring, of pi electrons

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13
Q

What are the conditions needed for hydrogenation of benzene?

A

Hydrogen, and heating under pressure with a nickel catalyst

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14
Q

What is the equation for the hydrogenation of benzene?

A

C6H6 + 3H2 ——> C6H12

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15
Q

What type of flame does benzene give?

A

A smoky flame

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16
Q

What are halogen carriers?

A

Usually metal-halogen compounds such as aluminium chloride

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17
Q

What are the products of bromination of benzene?

A

Bromobenzene and hydrogen bromide

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18
Q

What is nitration of benzene?

A

The substitution of a hydrogen atom by a nitro group, NO2

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19
Q

What are the conditions needed for nitration of benzene?

A

Warming it with a mixture of conc nitric acid and sulfuric acid catalyst

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20
Q

What are the products of nitration of benzene?

A

Nitrobenzene and water

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21
Q

What are two of the types of Friedel-Crafts reactions?

A

Alkylation and acylation

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22
Q

What are the features all Friedel-Crafts reactions have in common?

A

Using reagent XY, one of the hydrogens In benzene is substituted by Y, and the other product is HX
A catalyst is needed
Anyhydrous conditions are needed because water would react with catalyst and organic product

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23
Q

What is an alkyl group?

A

CH3

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24
Q

What is an acyl group?

A

COCH3

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25
Q

What is the reactant for alkylation of benzene?

A

A halogenalkane, such as CH3Cl

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26
Q

What are the products of alkylation of benzene?

A

An alkylbenzene such as methylbenzene and hydrogen chloride

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27
Q

What are the products of the acylation of benzene?

A

A ketone (phenylethanone) and hydrogen chloride

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28
Q

What name is often used when the benzene ring is attached of another functional group?

A

Phenyl or phen

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29
Q

What makes benzene act as an electrophile?

A

The delocalised electrons

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30
Q

How does Bromine react with the catalyst in Bromination of Benzene?

A

It forms Br+

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31
Q

What is the equation for the reaction between Bromine and the halogen carrier in Bromination?

A

AlCl3 + Br2 ——> Br+ + AlCl3Br-

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32
Q

What are the inorganic products formed in the bromination of benzene?

A

AlCl3 and HBr

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33
Q

What is the first step in Nitration of Benzene?

A

Formation of an electrophile through nitric acid and sulfuric acid reacting to form NO2+

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34
Q

What is the equation for the reaction to form an electrophile?

A

HNO3 + H2SO4 ——> NO2+ HSO4- +H2O

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35
Q

What type of mechanism is Alkylation of benzene?

A

Electrophillic substitution

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36
Q

What are the inorganic products in alkylation?

A

HCl and AlCl3

37
Q

What are the organic products in acylation?

A

HCl and AlCl3

38
Q

What does Friedel-Crafts Acylation produce?

A

Phenylketones

39
Q

What is benzene refluxed with in acylation?

A

An acyl chloride

40
Q

What must the temperature be kept below for nitration of benzene?

A

55 degrees C

41
Q

What happens if the temperature is above 55 for nitration of benzene?

A

Multiple substitutions occur

42
Q

Why is phenol more reactive than benzene

A

The OH group makes it more likely to undergo electrophillic substitution
One of the lone pairs in oxygen p orbital overlaps with the delocalised pi bonds in benzene ring
This means lone pair of oxygen electrons becomes partially delocalised, increasing electron density of the ring

43
Q

What happens if you shake phenol with bromine water?

A

It decolourises it

44
Q

Why does substitution occur more than once on phenol?

A

The OH group makes it very attractive to electrophiles

45
Q

What can aspirin be synthesised from?

A

Salicylic acid and ethanoic anhydride

46
Q

What is the amine functional group?

A

-NR2, where R is an alkyl group or hydrogen

47
Q

What can aliphatic amines be made from?

A

Halogenoalkanes or nitriles

48
Q

What are amines?

A

Weak bases, as they accept protons

49
Q

What does the strength of the amine base depend on?

A

How available the nitrogen’s lone pair of electrons is

50
Q

What is the order of basicity?

A

Primary aromatic amine < Ammonia < Primary aliphatic amine

51
Q

Why are the aliphatic amines the strongest bases?

A

The distribution of negative charge is distributed entirely on the lone pair, whereas in the aromatic amine it is distributed widely

52
Q

What are small amines soluble in?

A

Water, as the amine group can form hydrogen bonds with the water molecule

53
Q

The bigger the amine the greater the…

A

…London forces

54
Q

What kind of solutions do amines form?

A

Alkaline

55
Q

What do amines form with Copper (II) ions?

A

Complex ions

56
Q

What complexes do Cu2+ ions form with water?

A

[Cu(H2O)6]2+ - a blue solution

57
Q

What complex is formed if a small amount of butylamine solution is added?

A

[Cu(OH)2(H2O)4] - a blue precipitate

58
Q

If more butylamine solution is added, how does the complex change?

A

[Cu(CH3(CH2)3NH2)4(H2O)2]2+ - a deep blue solution

59
Q

How do amines react with halogenoalkanes?

A

In nucleophillic substitution reactions

60
Q

How can N-Substituted Amides be made from amines?

A

By acetylation

61
Q

Amides are…

A

…carboxylic acid derivatives

62
Q

What is the amide functional group?

A

-CONH2

63
Q

Why do amides behave differently from amines?

A

Because the carbonyl group pulls electrons away from the rest of the group

64
Q

What suffix do amides have?

A

-amide

65
Q

What can amides be made from?

A

Acyl chlorides

66
Q

What are the reactants needed to make a primary amide?

A

An acyl chloride and concentrated ammonia

67
Q

What reactants are needed to make an N-substituted amide?

A

An acyl chloride and primary amine

68
Q

What is an N-substituted amide?

A

One of the hydrogens in NH2 is substituted with an alkyl group

69
Q

What are amide links?

A

-CONH-

70
Q

What reacts to form an amide link?

A

-COOH and -NH2

71
Q

Which two types of molecule form a polyamide?

A

Dicarboxylic acids and diamines

72
Q

What are proteins?

A

Condensation polymers of amino acids

73
Q

What is needed to hydrolyse a protein into amino acids?

A

6moldm-3 hydrochloric acid and reflux

74
Q

Which two types of molecule form a polyester?

A

Dicarboxylic acids and diols

75
Q

What is an ester link?

A

-COO-

76
Q

What functional groups do amino acids have?

A

NH2 and COOH

77
Q

What is a zwitterion?

A

An overall neutral molecule that has a positivie and negative charge on different parts of the molecule

78
Q

In acidic conditions, which part of the amino acid is changed?

A

The NH2 becomes protonated, forming NH3+

79
Q

What charges does the amino acid have at its isoelectric point?

A

The NH2 becomes NH3+ and the COOH becomes COO-

80
Q

In alkaline conditions, which part of the amino acid is changed?

A

The COOH group becomes COO-

81
Q

Most amino acids are…

A

…chiral

82
Q

What can be used to identify unknown amino acids?

A

Paper chromatography

83
Q

How would you calculate an Rf value?

A

Distance travelled by spot/distance travelled by solvent

84
Q

What is the general formula of a Gringard reagent?

A

RMgX

85
Q

How are Gringards reagents made?

A

By refluxing a halogenoalkane with magnesium in dry ether

86
Q

What would a Gringard’s reagent + CO2 form?

A

A carboxylic acid

87
Q

What are the conditions needed to form a carboxylic acid from Gringards and CO2?

A

Dry ether and dilute HCl

88
Q

What do Gringards form in reaction with aldehydes and ketones?

A

Alcohols

89
Q

What are the conditions needed to form an alcohol from Gringards + carbonyl?

A

Dry ether and dilute HCl

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