6 - organic

Question 1

What is the mechanism that involves substitution reactions?

Answer 1

Chlorination

Chlorination is a type of substitution reaction where a chlorine atom replaces a hydrogen atom in a compound.

Question 2

What type of reaction occurs when UV light is applied in chlorination?

Answer 2

Free radical substitution

Free radical substitution involves the formation of free radicals that lead to the substitution of atoms in a molecule.

Question 3

What is the first step in the initiation of chlorination?

Answer 3

Homolytic fission

Homolytic fission is the process where a bond breaks evenly, resulting in two free radicals.

Question 4

What is the process of adding hydrogen across the double bond of an alkene called?

Answer 4

Hydrogenation

Hydrogenation typically requires a catalyst, such as nickel, and occurs under neat conditions.

Question 5

What is the process of adding water as steam across the double bond of an alkene known as?

Answer 5

Hydration

Hydration reactions often use H3PO4 as a catalyst and occur under high pressure.

Question 6

What occurs during the propagation step of a free radical reaction?

Answer 6

Two steps:
Cl* + CH4 → *CH3 + HCl
CH3 + Cl2 → CHCl + Cl

Propagation involves the continuous generation of free radicals, which further react in the process.

Question 7

What is the termination step in a free radical reaction?

Answer 7

Combination of radicals

Termination occurs when two free radicals combine to form a stable product, effectively stopping the reaction.

Question 8

What is the general reaction type for adding hydrogen halides across alkenes?

Answer 8

Electrophilic addition

Electrophilic addition involves the addition of electrophiles to the nucleophilic double bond of an alkene.

Question 9

Fill in the blank: The catalyst used in hydration of alkenes is _______.

Answer 9

H3PO4

Question 10

What type of compound is formed when an alkene reacts with hydrogen iodide?

Answer 10

Halogenoalkane

Haloalkanes are compounds containing one or more halogen atoms substituted for hydrogen in an alkane.

Question 11

What is the product of the reaction between methane and chlorine under free radical conditions?

Answer 11

Chloromethane

Chloromethane is formed when a chlorine atom replaces a hydrogen atom in methane during chlorination.

Question 12

True or False: Hydrogenation requires the presence of a catalyst.

Answer 12

True

Question 13

What type of alkene is produced from the addition of hydrogen iodide?

Answer 13

Iodinated alkane

The addition of hydrogen iodide to an alkene results in an iodinated alkane.

Question 14

What is the mechanism for adding halogens across a double bond?

Answer 14

Halogen addition involves adding halogens across the double bond.

Question 15

What conditions are required for alkenes with manganate (VII) ions?

Answer 15

Cold, dilute, and acidified conditions are required for oxidising the alkene.

Question 16

What type of acids should be used with alkenes and manganate (VII) ions?

Answer 16

Always use strong acids.

Question 17

What is electrophilic addition?

Answer 17

Electrophilic addition involves the addition of electrophiles to alkenes.

Question 18

What is a carbocation?

Answer 18

A carbocation is an intermediate in electrophilic addition.

Question 19

What is Markovnikov’s rule?

Answer 19

In electrophilic addition of hydrogen halides to unsymmetrical alkenes, two products are formed: a major and a minor product.

Question 20

What determines the major product in Markovnikov’s rule?

Answer 20

The major product forms the most stable carbocation intermediate, typically tertiary carbocations.

Question 21

What is the stability order of carbocations?

Answer 21

Tertiary > Secondary > Primary.

Question 22

What is a 1,2-diol?

Answer 22

A 1,2-diol is a compound with two hydroxyl groups on adjacent carbon atoms.

Question 23

What is the role of alkyl groups in stabilizing carbocations?

Answer 23

Alkyl groups attract electron density, stabilizing the positive charge on the carbocation.

Question 24

What are carboxylic acids considered?

Answer 24

Organic acids

Carboxylic acids are organic acids that typically have a -COOH group.

Question 25

What is the formula for propanoic acid?

Answer 25

C2H5COOH ## Footnote Propanoic acid is an example of a carboxylic acid.

Question 26

Carboxylic acids end in which suffix?

Answer 26

-oic acid ## Footnote This suffix indicates the presence of a carboxylic functional group.

Question 27

What is the general formula for alkanes?

Answer 27

CnH2n+2 ## Footnote Alkanes are saturated hydrocarbons with single bonds.

Question 28

What type of bonds do alkanes form?

Answer 28

Non-polar bonds ## Footnote Alkanes primarily consist of C-C and C-H bonds, which are non-polar.

Question 29

What happens to bromine water in the presence of alkenes?

Answer 29

Changes from orange to colorless ## Footnote This reaction indicates the unsaturation of alkenes.

Question 30

What is the characteristic structure of aldehydes?

Answer 30

One carbon chain and a hydrogen atom ## Footnote Aldehydes contain the carbonyl group (C=O) at the end of the carbon chain.

Question 31

Aldehydes typically end in which suffix?

Answer 31

-al ## Footnote This suffix denotes the presence of an aldehyde functional group.

Question 32

What reagent is used to differentiate carbonyl compounds?

Answer 32

2,4-DNPH ## Footnote 2,4-DNPH (2,4-dinitrophenylhydrazine) is used to identify aldehydes and ketones.

Question 33

What is the general structure of alcohols?

Answer 33

R-OH ## Footnote Alcohols contain a hydroxyl (-OH) group.

Question 34

Why do alcohols have higher boiling points than alkanes?

Answer 34

Due to hydrogen bonding ## Footnote Alcohols can form hydrogen bonds, which increases their boiling points.

Question 35

What is the simplest ketone?

Answer 35

Propanone ## Footnote Propanone is also known as acetone.

Question 36

Ketones end with which suffix?

Answer 36

-one ## Footnote This suffix indicates the presence of a carbonyl group within the chain.

Question 37

What characterizes alkenes?

Answer 37

Unsaturated C=C bond ## Footnote Alkenes contain at least one double bond between carbon atoms.

Question 38

What type of reaction do alkenes undergo?

Answer 38

Addition reactions ## Footnote Alkenes can react with halogens and other reagents through addition mechanisms.

Question 39

What distinguishes haloalkanes?

Answer 39

Presence of halogen bonded with an alkane ## Footnote Haloalkanes are derived from alkanes where one or more hydrogen atoms are replaced by halogen atoms.

Question 40

What mechanism involves a two-step process for halogenoalkanes?

Answer 40

Nucleophilic substitution ## Footnote This mechanism often involves the attack of a nucleophile on the electrophilic carbon.

Question 41

What types of haloalkanes exist based on the carbon's substitution?

Answer 41

Primary, secondary, and tertiary ## Footnote The classification depends on the number of carbon atoms bonded to the carbon with the halogen.

Question 42

alkane → alkene

Answer 42

cracking

Question 43

alkene → alkane

Answer 43

hydrogenation (Ni catalyst, heat)

Question 44

alkene → halogenoalkane

Answer 44

halogenation (rtp)

Question 45

alkene → alcohol

Answer 45

. addition / hydration (H₃PO₄ catalyst, heat, high pressure) . oxidation (dilute NaOH)

Question 46

alkene → diol

Answer 46

oxidation (cold, dilute, acidified manganate (VII)

Question 47

halogenoalkane → alkene

Answer 47

elimination (warm NaOH dissolved in ethanol, heated under reflux)

Question 48

halogenoalkane → alcohols

Answer 48

nucleophilic substitution hydrolysis or dilute alkali {sodium hydroxide} (heat under reflux)

Question 49

alcohols → halogenoalkane

Answer 49

nucleophilic substitution with hydrogen halide chlorine - add PCl₅ bromine - add HBr iodine - PI₃

Question 50

alcohols → alkene

Answer 50

elimination / dehydration (conc H₃PO₄ catalyst)

Question 51

alkene → ketone

Answer 51

oxidation

Question 52

alcohols → carboxylic acids

Answer 52

full oxidation of **primary** alcohols (acidified dichromate, heated under reflux)

Question 53

alkene → aldehyde

Answer 53

oxidation

Question 54

alcohols → aldehyde

Answer 54

partial oxidation of **primary** alcohols (acidified dichromate, heat + distill)

Question 55

alcohols → ketone

Answer 55

oxidation of **secondary** alcohols (acidified dichromate, heat + distill)

Question 56

aldehyde → alcohols

Answer 56

reduction (NaBH₄)

Question 57

ketone → alcohols

Answer 57

oxidation (NaBH₄)

Question 58

aldehyde → carboxylic acids

Answer 58

oxidation (K₂Cr₂O₇ or Na₂Cr₂O₇)

Question 59

carboxylic acids → alcohols

Answer 59

reduction

Question 60

carboxylic acids → aldehyde

Answer 60

reduction

Question 61

alkane → halogenoalkane

Answer 61

free radical substitution

Question 62

halogenoalkane → nitrile

Answer 62

nucleophilic substitution with ethanolic potassium cyanide, warm, reflux

Question 63

describe two characteristics of a homologous series

Answer 63

- compounds have the same functional group - they have similar chemical properties

Question 64

# (3) catalytic cracking

Answer 64

- converting alkanes into alkenes & smaller alkanes - done with zeolite to lower temp and pressure - about 450°C

Question 65

what is meant by free radical?

Answer 65

species with an unpaired electron

Question 66

why do we use an large excess of ammonia?

Answer 66

ensures that further substitution doesn’t take place

Question 67

# (3) thermal cracking

Answer 67

- to break down alkanes into smaller alkanes & alkenes - hard temps and pressures - about 1000°C and 70 atm pressure

Question 68

chain/structural isomerism

Answer 68

the carbon chain is rearranged to create different structures ## Footnote pentane = methylbutane = dimethylpropane

Question 69

positional isomerism

Answer 69

when a functional group changes position ## Footnote pentan-1-ol, pentan-2-ol, pentan-3-ol

Question 70

functional isomerism

Answer 70

compounds have the same molecular formula but different functional groups ## Footnote ethanol = methoxymethane

Question 71

halogenoalkane → amine

Answer 71

nucleophilic substitution with excess ethanolic ammonia (warm)