organic chemistry 3

Question 1

what is the formula for benzene

Answer 1

C₆H₆

Question 2

what are the two ways of representing benzene

Answer 2

kekule model delocalised model

Question 3

What was Friedrich August Kekulé’s proposal about the structure of benzene?

Answer 3

Kekulé proposed that benzene was made up of a planar (flat) ring of carbon atoms with alternating single and double bonds between them.

Question 4

What additional atoms did Kekulé propose were bonded to each carbon atom in benzene?

Answer 4

In Kekulé’s model, each carbon atom is also bonded to one hydrogen atom.

Question 5

How did Kekulé adapt his model of the benzene molecule?

Answer 5

He later adapted the model to propose that the benzene molecule was constantly flipping between two forms (isomers) by switching over the double and single bonds.

Question 6

What would you expect the bond lengths to be in benzene according to the Kekulé model?

Answer 6

According to the Kekulé model, you’d expect benzene to have three bonds with the length of a C–C bond (154 pm) and three bonds with the length of a C=C bond (134 pm).

Question 7

What have X-ray diffraction studies revealed about the carbon-carbon bonds in benzene?

Answer 7

X-ray diffraction studies have shown that all the carbon-carbon bonds in benzene have the same length of 140 pm, which is between the length of a single bond and a double bond.

Question 8

What does the consistency in bond lengths observed in benzene indicate about the Kekulé model?

Answer 8

The consistent bond length of 140 pm observed in benzene suggests that the Kekulé structure cannot be entirely accurate.

Question 9

What does the delocalised model propose about the bonding in benzene?

Answer 9

The delocalised model proposes that benzene’s bonding involves delocalised pi-bonds formed by the overlapping of p-orbitals on carbon atoms.

Question 10

How are sigma-bonds formed in the delocalised model of benzene?

Answer 10

In the delocalised model, each carbon atom forms three s-bonds—one to a hydrogen atom and one to each of its neighboring carbon atoms—due to head-on overlap of their atomic orbitals.

Question 11

What happens to the remaining p-orbital on each carbon atom in the delocalised model of benzene?

Answer 11

Each carbon atom has one remaining p-orbital containing one electron, which overlaps sideways with the p-orbitals of neighboring carbon atoms to form a ring of delocalised p-bonds.

Question 12

How are the electrons in the delocalised model of benzene represented, and why?

Answer 12

The electrons in the delocalised model are represented as a circle inside the ring of carbons rather than as double or single bonds because they are delocalised and do not belong to a specific carbon atom.

Question 13

What happens when you react an alkene with hydrogen gas?

Answer 13

Two atoms of hydrogen add across the double bond, a process known as hydrogenation, and the enthalpy change of the reaction is called the enthalpy change of hydrogenation.

Question 14

What is the expected enthalpy change of hydrogenation for benzene based on the Kekulé structure?

Answer 14

If benzene had three double bonds (as in the Kekulé structure), the expected enthalpy change of hydrogenation would be (3 × 120 =) –360 kJ mol–1.

Question 15

when cyclohexane is hydrogenated what is the enthalpy change of hydrogenation

Answer 15

-120 kj mol⁻¹

Question 16

What is the experimental enthalpy change of hydrogenation for benzene, and how does it compare to the expected value?

Answer 16

The experimental enthalpy change of hydrogenation for benzene is –208 kJ mol–1, which is far less exothermic than the expected value.

Question 17

What conclusion can be drawn from the discrepancy between the expected and experimental enthalpy changes of hydrogenation for benzene?

Answer 17

The discrepancy suggests that more energy must have been put in to break the bonds in benzene than would be needed to break the bonds in the Kekulé structure.

Question 18

What does the discrepancy between the expected and experimental enthalpy changes of hydrogenation for benzene indicate about its stability?

Answer 18

The difference indicates that benzene is more stable than the Kekulé structure would be.

Question 19

what does the difference in in energy indicate about benzene and the kekule model

Answer 19

This difference indicates that benzene is more stable than the Kekulé structure would be.

Question 20

What is thought to be the reason for benzene’s extra stability compared to the Kekulé structure?

Answer 20

The extra stability of benzene is thought to be due to the delocalised ring of electrons.

Question 21

How do alkenes react with bromine water at room temperature, and what is the result?

Answer 21

Alkenes react easily with bromine water at room temperature, decolorizing the brown bromine water. This reaction is an electrophilic addition reaction, where the bromine atoms are added across the double bond of the alkene.

Question 22

What is the expected reaction between benzene and bromine based on the Kekulé structure, and what are the actual conditions required for this reaction?

Answer 22

Based on the Kekulé structure, one would expect a similar reaction between benzene and bromine. However, to make it happen, you need hot benzene and ultraviolet light, and it remains difficult.

Question 23

How is the difference in reactivity between benzene and other alkenes explained?

Answer 23

The difference is explained by the presence of delocalized p-bonds in benzene, which spread out the negative charge and make the benzene ring very stable. Therefore, benzene is reluctant to undergo addition reactions that would destroy the stable ring.

Question 24

what type of reaction does benzene prefer to undergo, and why?

Answer 24

Benzene prefers to undergo electrophilic substitution reactions instead of addition reactions. This is because in alkenes, the p-bond in the C=C double bond attracts electrophiles strongly due to its localized high electron density. In benzene, however, this attraction is reduced due to the negative charge being spread out.

Question 25

What happens when benzene is burned in oxygen?

Answer 25

When benzene is burned in oxygen, it produces carbon dioxide and water.

Question 26

What occurs if benzene is burned in air?

Answer 26

2C₆H₆ + 15O₂ ⟶ 12CO₂ + 6H₂O
If benzene is burned in air, a very smoky flame is produced due to insufficient oxygen for complete combustion. Many carbon atoms remain unburned and form particles of soot in the hot gas, resulting in a smoky flame.

Question 27

what happens when you burn benzene in air

Answer 27

If you burn benzene in air, you get a very smoky flame — there’s too little oxygen to burn the benzene completely. A lot of the carbon atoms stay as carbon and form particles of soot in the hot gas — making the flame smoke.

Question 28

What are compounds containing a benzene ring commonly called?

Answer 28

arenes or ‘aromatic compounds’

Question 29

Why doesn’t benzene undergo electrophilic addition reactions like alkenes?

Answer 29

Benzene doesn’t undergo electrophilic addition reactions like alkenes because addition reactions would break the very stable ring of delocalised pi-bonds.

Question 30

Describe the process of electrophilic substitution reactions in benzene.

Answer 30

In electrophilic substitution reactions, a hydrogen atom in benzene is substituted by an electrophile.

Question 31

What are the two steps involved in the mechanism of electrophilic substitution reactions in benzene?

Answer 31

The mechanism involves two steps: addition of the electrophile to form a positively charged intermediate, followed by loss of H+ from the carbon atom attached to the electrophile, reforming the delocalised ring.

Question 32

Why does an electrophile need to have a strong positive charge to attack the benzene ring?

Answer 32

The delocalised p-bonds in benzene spread out the charge density across the ring, requiring an electrophile with a strong positive charge to effectively attack the benzene ring.

Question 33

How can some compounds be made into stronger electrophiles for attacking the benzene ring?

Answer 33

Some compounds can be made into stronger electrophiles using a catalyst called a halogen carrier.

Question 34

What role does a halogen carrier play in making compounds stronger electrophiles?

Answer 34

a halogen carrier polarises halogens such as br2 and cl2 the positive part of the halogen acts as the electrophile

Question 35

Name some examples of halogen carriers.

Answer 35

Halogen carriers include aluminium halides, iron halides, and iron.

Question 36

What are Friedel-Crafts reactions used for in organic synthesis?

Answer 36

Friedel-Crafts reactions are used for forming C–C bonds in organic synthesis.

Question 37

What are the two types of Friedel-Crafts reactions?

Answer 37

The two types are Friedel-Crafts alkylation and Friedel-Crafts acylation.

Question 38

Describe Friedel-Crafts alkylation.

Answer 38

Friedel-Crafts alkylation puts any alkyl group onto a benzene ring using a halogenoalkane and a halogen carrier.

Question 39

Describe Friedel-Crafts acylation.

Answer 39

Friedel-Crafts acylation substitutes an acyl group for a hydrogen atom on benzene, typically using an acyl chloride instead of a halogenoalkane.

Question 40

What conditions are required for Friedel-Crafts reactions to occur?

Answer 40

The reactants need to be heated under reflux in a non-aqueous solvent (like dry ether) for Friedel-Crafts reactions to occur.

Question 41

What happens when benzene is warmed with concentrated nitric acid and concentrated sulfuric acid?

Answer 41

When benzene is warmed with concentrated nitric acid and concentrated sulfuric acid, a nitration reaction occurs, and nitrobenzene is formed.

Question 42

What role does sulfuric acid play in the nitration reaction of benzene?

Answer 42

Sulfuric acid acts as a catalyst in the nitration reaction of benzene, facilitating the formation of the nitronium ion (NO2+), which is the electrophile.

Question 43

what is the formula for phenol

Answer 43

C₆H₅OH

Question 44

What property of phenol makes it more likely to undergo electrophilic substitution than benzene?

Answer 44

The presence of the -OH group makes phenol more likely to undergo electrophilic substitution than benzene.

Question 45

How does the lone pair of electrons from the oxygen atom in the -OH group of phenol contribute to its reactivity?

Answer 45

One of the lone pairs of electrons in a p-orbital of the oxygen atom overlaps with the delocalised p-bonds in the benzene ring, causing the lone pair of electrons from the oxygen atom to be partially delocalised into the p-system.

Question 46

How does the partial delocalization of the lone pair of electrons from the oxygen atom affect the reactivity of phenol?

Answer 46

This increases the electron density of the ring, making it more likely to be attacked by electrophiles.

Question 47

How does phenol react with orange bromine water?

Answer 47

Phenol reacts with orange bromine water, causing it to decolorize.

Question 48

Why does substitution occur more than once when phenol reacts with electrophiles?

Answer 48

The -OH group in phenol makes the ring highly attractive to electrophiles, leading to multiple substitution reactions.

Question 49

What is the product formed when phenol reacts with orange bromine water, and what are its properties?

Answer 49

The product formed is 2,4,6-tribromophenol, which is insoluble in water and precipitates out of the mixture. It has a characteristic antiseptic smell.

Question 50

How can aspirin be synthesized using phenol?

Answer 50

Aspirin can be synthesized through an esterification reaction of salicylic acid, which is a derivative of phenol.

Question 51

What steps are involved in the synthesis of aspirin from salicylic acid?

Answer 51

1. Add ethanoic anhydride and a few drops of phosphoric acid to salicylic acid in a test tube.
2. Warm the reaction mixture to 50 °C and leave it for about 15 minutes.
3. Add cold water to the reaction mixture, then cool it on ice to allow aspirin crystals to form.
4. Filter the crystals under reduced pressure.
5. Recrystallize the aspirin in a mixture of water and ethanol.

Question 52

What is an amine?

Answer 52

An amine is a compound derived from ammonia (NH3) where one or more of the hydrogens is replaced with an organic group.

Question 53

what is the functional group of a amine

Answer 53

The functional group of amines is -NR2, where R is an alkyl group or hydrogen.

Question 54

How are amines classified based on the number of alkyl groups bonded to the nitrogen atom?

Answer 54

Amines can be classified as primary, secondary, or tertiary depending on how many alkyl groups the nitrogen atom is bonded to.

Question 55

What is a quaternary ammonium ion?

Answer 55

A quaternary ammonium ion is formed when the nitrogen atom in ammonia is bonded to four alkyl groups, resulting in a positively charged ion.

Question 56

How can amines be synthesized using halogenoalkanes and ethanolic ammonia?

Answer 56

Amines can be synthesized by heating a halogenoalkane with an excess of ethanolic ammonia.

Question 57

What is the limitation of synthesizing amines using halogenoalkanes and ethanolic ammonia?

Answer 57

The limitation is that this method yields a mixture of primary, secondary, and tertiary amines, as well as quaternary ammonium salts.

Question 58

Why does the reaction of halogenoalkanes with ethanolic ammonia result in a mixture of different types of amines?

Answer 58

The nitrogen atom in primary, secondary, and tertiary amines has a lone pair of electrons, allowing it to act as a nucleophile. It can participate in nucleophilic substitution reactions with any halogenoalkane in the reaction mixture, leading to the production of more substituted amines where more than one hydrogen is replaced.

Question 59

How can a nitrile be reduced to a primary amine in the laboratory?

Answer 59

A nitrile can be reduced to a primary amine in the laboratory using lithium aluminium hydride (LiAlH4) in a non-aqueous solvent, followed by treatment with dilute acid.

Question 60

What is the industrial method for reducing nitriles to primary amines?

Answer 60

In industry, nitriles are reduced to primary amines using hydrogen gas with a metal catalyst, such as platinum or nickel, at high temperature and pressure. This process is called catalytic hydrogenation.

Question 61

How are aromatic nitro compounds reduced to aromatic amines in two steps?

Answer 61

1) Heat a mixture of a nitro compound, tin metal, and concentrated hydrochloric acid under reflux to form a salt.
2) To obtain the aromatic amine, add sodium hydroxide.

Question 62

Why do amines act as weak bases?

Answer 62

Amines act as weak bases because they accept protons. The lone pair of electrons on the nitrogen atom can form a dative covalent (coordinate) bond with an H+ ion.

Question 63

What factors influence the strength of a base in amines?

Answer 63

The strength of the base depends on the availability of the lone pair of electrons on the nitrogen atom. The more available the lone pair is, the more likely the amine is to accept a proton, and the stronger a base it will be.

Question 64

How does the availability of the lone pair of electrons affect the strength of a base in amines?

Answer 64

A lone pair of electrons will be more available if its electron density is higher, making the amine more likely to accept a proton and stronger as a base.

Question 65

How does the basicity of primary aliphatic amines compare to that of ammonia and aromatic amines?

Answer 65

Primary aliphatic amines are stronger bases than ammonia, which is stronger than aromatic amines.

Question 66

Why are primary aliphatic amines stronger bases than ammonia?

Answer 66

Alkyl groups attached to primary aliphatic amines push electrons onto the nitrogen atom, increasing the electron density on the nitrogen and making the lone pair more available, resulting in stronger basicity.

Question 67

Why are aromatic amines weaker bases compared to primary aliphatic amines?

Answer 67

The benzene ring in aromatic amines draws electrons towards itself, causing partial delocalization of the nitrogen lone pair onto the ring. This decreases the electron density on the nitrogen, making the lone pair less available and resulting in weaker basicity.

Question 68

What type of reactions do amines undergo with halogenoalkanes and acyl chlorides?

Answer 68

Amines undergo nucleophilic substitution reactions with halogenoalkanes and react with acyl chlorides to form N-substituted amides.

Question 69

How do amines react with acids?

Answer 69

Amines react with acids to form ammonium salts.

Question 70

What is the reaction between butylamine and hydrochloric acid?

Answer 70

Butylamine reacts with hydrochloric acid to form butylammonium chloride.

Question 71

why are small amines soluble in water

Answer 71

Small amines are soluble in water because the amine group can form hydrogen bonds with water molecules.

Question 72

Why are larger amines less soluble in water than small ones?

Answer 72

Larger amines have greater London forces between molecules, requiring more energy to overcome. Additionally, the larger carbon chains disrupt hydrogen bonding with water. Thus, large amines are less soluble in water.

Question 73

when amines dissolve they from alkaline solutions so what happens to some of the amine molecules

Answer 73

When they dissolve, amines form alkaline solutions. Some of the amine molecules
in the solution take a hydrogen ion from water, forming alkyl ammonium ions and hydroxide ions.

Question 74

in copper (II) sulfate solution what do the Cu²⁺ ions do with water

Answer 74

from the [Cu(H₂O)₆]²⁺ complex

Question 75

what colour is the solution of the complex [Cu(H₂O)₆]²⁺

Answer 75

blue

Question 76

what happens if you add butylamine solution to copper (II) sulfate

Answer 76

you get a pale blue precipitate — the amine acts as a base (proton acceptor) and takes two H+ ions from the complex. This leaves a pale blue precipitate of copper hydroxide, [Cu(OH)₂(H₂O)₄], which is insoluble.

Question 77

what happens If you add excess butylamine to the coppersulfate solution

Answer 77

dd more butylamine solution, and the precipitate dissolves to form a beautiful deep blue solution. Some of the ligands are replaced by butylamine molecules, which donate their lone pairs to form dative covalent bonds with the Cu2+ ion. This forms soluble [Cu(CH₃(CH₂)₃NH₂)₄(H₂O)₂]²⁺ complex ions.

Question 78

What is the reaction mechanism for forming primary amines from ammonia and halogenoalkanes?

Answer 78

Nucleophilic substitution reaction — the lone pair on the ammonia molecule reacts with the d+ carbon in the halogenoalkane, displacing the halogen and forming a primary amine.

Question 79

What property of primary amines makes them nucleophiles?

Answer 79

The nitrogen atom in primary amines has a lone pair of electrons, making it a nucleophile.

Question 80

Do primary, secondary, and tertiary amines all possess a lone pair of electrons on their nitrogen atom?

Answer 80

Yes, primary, secondary, and tertiary amines all have a lone pair of electrons on their nitrogen atom.

Question 81

How do primary, secondary, and tertiary amines react with halogenoalkanes?

Answer 81

They undergo nucleophilic substitution reactions, where they replace the halogen atom in the halogenoalkane to form more substituted amines.

Question 82

What happens when amines react with acyl chlorides?

Answer 82

An H atom on the amine is replaced by the acyl group, RCO, to form an N-substituted amide and HCl. The produced HCl further reacts with another molecule of the amine to generate a salt.

Question 83

what functional group do amides have

Answer 83

-CONH₂

Question 84

How does the carbonyl group affect the behavior of amides compared to amines?

Answer 84

The carbonyl group in amides withdraws electrons, causing amides to behave differently from amines.

Question 85

What are the two types of amides that can be formed, and what determines their structure?

Answer 85

Primary amides and N-substituted amides. Their structure depends on the number of carbon atoms the nitrogen is bonded to.

Question 86

What is the naming convention for primary amides?

Answer 86

Primary amides are named by using the stem of the carbon chain followed by the suffix -amide.

Question 87

How are N-substituted amides named?

Answer 87

N-substituted amides are named using the prefix N-alkyl- to describe the alkyl chain attached directly to the nitrogen atom.

Question 88

What happens when an acyl chloride reacts with ammonia or a primary amine?

Answer 88

An amide is formed.

Question 89

What type of amide is formed when an acyl chloride reacts with concentrated ammonia at room temperature?

Answer 89

A primary amide is formed.

Question 90

What type of amide is formed when an acyl chloride reacts with a primary amine at room temperature?

Answer 90

An N-substituted amide is formed.

Question 91

What is typically involved in condensation polymerization?

Answer 91

Condensation polymerization typically involves two different types of monomers.

Question 92

What is the role of functional groups in condensation polymerization?

Answer 92

Each monomer has at least two functional groups, and each functional group reacts with a group on another monomer to form a link, creating polymer chains.

Question 93

Why is it called condensation polymerization?

Answer 93

Condensation polymerization is named because each time a link is formed, a small molecule (often water) is lost.

Question 94

What reaction occurs between carboxyl (–COOH) groups and amino (–NH2) groups?

Answer 94

They react to form amide (–CONH–) links.

Question 95

What happens each time an amide link is formed between carboxyl and amino groups?

Answer 95

A water molecule is lost, indicating a condensation reaction.

Question 96

What type of polymer is formed through the condensation reaction between carboxyl and amino groups?

Answer 96

A polyamide is formed.

Question 97

What functional groups are present in amino acids?

Answer 97

Amino acids contain both an amine and a carboxylic acid group.

Question 98

How do amino acid monomers form proteins through polymerization?

Answer 98

Amino acid monomers undergo condensation polymerization reactions, forming proteins linked by amide links, also known as peptide links.

Question 99

What type of reaction occurs between the amine group of one amino acid and the carboxylic acid group of another?

Answer 99

In a condensation reaction, the amine group of one amino acid reacts with the carboxylic acid group of another to form an amide link.

Question 100

How can you break down a protein into its individual amino acids?

Answer 100

You can hydrolyze a protein using hot aqueous 6 mol dm–3 hydrochloric acid under reflux for 24 hours. This produces the ammonium salts of the amino acids, which are then neutralized using a base.

Question 101

What method can be used to identify the amino acid monomers of a hydrolyzed protein?

Answer 101

Chromatography can be used to identify the amino acid monomers that a protein was made from.

Question 102

What reaction occurs between carboxyl groups (–COOH) and hydroxyl groups (–OH)?

Answer 102

They react to form ester links (–COO–).

Question 103

What type of reaction is the formation of ester links between carboxyl and hydroxyl groups?

Answer 103

It’s another condensation reaction.

Question 104

What type of polymer is formed through the condensation reaction between carboxyl and hydroxyl groups?

Answer 104

A polyester is formed.

Question 105

How can you determine the formulae of monomers used to make a condensation polymer?

Answer 105

1. Find the amide (HN–CO) or ester (CO–O) link in the repeat unit.
2. Break it down the middle.
3. Add an H or an OH to both ends of both molecules to find the monomers.
4. Always add Hs to O or N atoms and OH groups to C atoms.

Question 106

How can you determine the repeat unit of a condensation polymer formed from a pair of monomers?

Answer 106

1. Draw out the two monomer molecules next to each other.
2. Remove an OH from the dicarboxylic acid and an H from the diamine to form a water molecule.
3. Join the carbon and the nitrogen together to make an amide link.
4. Remove another H and OH from the ends of the molecule to find the repeat unit.

Question 107

What are amino acids often referred to as?

Answer 107

Amino acids are often called the building blocks of life.

Question 108

What are amino acids primarily used for in the body?

Answer 108

Amino acids are primarily used to make all the proteins in the body.

Question 109

What functional groups does an amino acid contain?

Answer 109

An amino acid contains a basic amino group (NH2) and an acidic carboxyl group (COOH).

Question 110

Why are amino acids considered amphoteric?

Answer 110

Amino acids are considered amphoteric because they possess both acidic and basic properties.

Question 111

What distinguishes 2-amino acids from other types of amino acids?

Answer 111

2-amino acids are the type of amino acids found in nature, with the amino group positioned on carbon-2 (the carboxyl group is always carbon-1).

Question 112

What is a zwitterion?

Answer 112

A zwitterion is an overall neutral molecule that has both a positive and a negative charge in different parts of the molecule.

Question 113

Under what conditions can an amino acid exist as a zwitterion?

Answer 113

An amino acid can only exist as a zwitterion near its isoelectric point, which is the pH where the overall charge on the amino acid is zero.

Question 114

What factors determine the isoelectric point of an amino acid?

Answer 114

The isoelectric point of an amino acid depends on its R group, and it varies for different amino acids.

Question 115

What happens to the –NH2 group of an amino acid in conditions more acidic than its isoelectric point?

Answer 115

The –NH2 group is likely to be protonated.

Question 116

What is the state of the carboxyl and amino groups of an amino acid at its isoelectric point?

Answer 116

At the isoelectric point, both the carboxyl group and the amino group are likely to be ionized, forming a zwitterion.

Question 117

What happens to the –COOH group of an amino acid in conditions more basic than its isoelectric point?

Answer 117

The –COOH group is likely to lose its proton.

Question 118

Under what condition will an amino acid exist as a zwitterion when dissolved in solution?

Answer 118

If the amino acid contains the same number of carboxyl groups as amino groups, it will exist as a zwitterion.

Question 119

What is the pH of a zwitterionic amino acid solution?

Answer 119

A zwitterionic amino acid solution will have a pH of about 7, making it roughly neutral.

Question 120

What are the four different groups attached to carbon-2 of a 2-amino acid?

Answer 120

The carboxyl group, the amino group, a hydrogen atom, and the R group.

Question 121

Why are 2-amino acids considered chiral molecules?

Answer 121

2-amino acids are considered chiral molecules because they have four different groups attached to carbon-2, resulting in two optical isomers.

Question 122

What happens when plane-polarized, monochromatic light passes through an aqueous solution containing one enantiomer of a 2-amino acid?

Answer 122

The plane of the light gets rotated due to the presence of the chiral carbon.

Question 123

What is the exception to the rule of enantiomers rotating the plane of plane-polarized light?

Answer 123

Glycine is the exception. It has two H atoms attached to the central carbon, making it achiral, and it won’t rotate the plane of plane-polarized light.

Question 124

What is the general formula for Grignard reagents?

Answer 124

The general formula for Grignard reagents is RMgX, where R is an alkyl group and X is a halogen.

Question 125

How are Grignard reagents typically prepared?

Answer 125

Grignard reagents are prepared by refluxing a halogenoalkane with magnesium in dry ether.

Question 126

Provide an example of the preparation of a Grignard reagent.

Answer 126

Refluxing bromoethane with magnesium in dry ether would create the following Grignard reagent.

Question 127

What are the two steps to make a carboxylic acid from a Grignard reagent

Answer 127

1) Bubble carbon dioxide gas through a Grignard reagent in dry ether.
2) Add a dilute acid, such as hydrochloric acid.

Question 128

What happens during the reaction between carbon dioxide and a Grignard reagent?

Answer 128

During the reaction, a new C–C bond forms between the carbon atom in carbon dioxide and the C–Mg carbon from the Grignard reagent. One of the C=O bonds in carbon dioxide is broken to form a -COO– group, which is protonated when the dilute acid is added to form a carboxylic acid (-COOH).

Question 129

What happens when Grignard reagents react with aldehydes and ketones?

Answer 129

Grignard reagents react with aldehydes and ketones to make alcohols. A new C–C bond forms between the C–Mg carbon atom from the Grignard reagent and the C=O carbon of the carbonyl. This causes the C=O bond to break, and when acid is added, an -OH group is formed.

Question 130

What type of reactions does benzene participate in instead of electrophilic addition reactions?

Answer 130

Benzene participates in electrophilic substitution reactions instead of electrophilic addition reactions.