Chapter 14- Introduction to Organic Chemistry

Question 1

chap 14:

bonds in a C=C bond

Answer 1

one pi and one sigma

Question 2

types of structural isomerism

Answer 2

1. positional isomerism
2. functional group isomerism
3. chain isomerism

Question 3

describe positional isomerism

Answer 3

the position of the functional group varies in each isomer

Question 4

describe functional group isomerism

Answer 4

the functional group varies in each isomer

Question 5

describe chain isomerism

Answer 5

the chain differs in both isomers; for example one could be a straight chain and the other could be branched

Question 6

types of stereoisomerism

Answer 6

1. cis/Z and trans/E

2. optical

Question 7

describe cis/ trans isomerism

Answer 7

1. only happens with alkenes
2. in cis/Z, the same type of atoms are on the same side of the compound and in trans/E, the atoms are on different sides

Question 8

describe optical isomerism

Answer 8

contains a chiral centre

Question 9

chap 15:

what is true for every nucleophile?

Answer 9

contains a lone pair (donates a pair of electrons)

Question 10

crude oil contains what type of organic compounds ?

Answer 10

alkanes

Question 11

before fractional distillation, what happens to crude oil?

Answer 11

vaporization

Question 12

initiation, propagation and termination reactions

Answer 12

initiation:
Cl2 = 2Cl⚫️ (condition: UV light)

propagation:
CH4 + Cl⚫️ = ⚫️CH3 + HCl

termination:
⚫️CH3 + Cl⚫️ = CH3Cl

Question 13

Give the condition and reagent of the reaction when hydrogen is added to alkenes. What is the product formed?

Answer 13

reagent: H2
condition: Ni catalyst, 140 deg cel

product: alkane

Question 14

Give the condition and reagent of the reaction when steam is added to alkenes. What is the product formed?

Answer 14

reagent: H2O
condition: H3PO4 catalyst, 330 deg cel, 6MPa pressure

product: alcohol

Question 15

Give the condition and reagent of the reaction when hydrogen halides are added to alkenes. What is the product formed?

Answer 15

reagent: HX (X=F, Cl, Br, I)
condition: alkene is bubbled through concentrated solution of HX at room temperature

product: halogenoalkane

Question 16

State the Markonikov’s rule

Answer 16

the major product is the one where the hydrogen attaches itself to the carbon with the most number of hydrogens (or where the halogen atom attaches to the carbon with least number of hydrogens)

Question 17

What mechanism is for alkenes?

Answer 17

electrophilic addition

Question 18

what happens when cold dilute acidified manganate is added to alkenes?

Answer 18

1. a diol is formed
2. solution turns from pale purple to colorless
3. reaction is done at room temperature

Question 19

what happens when hot concentrated manganate is added to alkenes?

Answer 19

no R groups attached to C: CO2
1 R group attached to C: aldehyde further oxidized to carboxylic acid
2 R groups attached to C: a ketone

Question 20

chap 16:

mechanism of halogenoalkanes

Answer 20

nucleophilic substitution

Question 21

Give the condition and reagent of the reaction when aqueous alkali is added to halogenoalkanes. What is the product formed?

Answer 21

reagent: NaOH
condition:

product: alcohol
(this is a nucleophilic substitution reaction)

Question 22

Give the condition and reagent of the reaction when alcoholic alkali is added to halogenoalkanes. What is the product formed?

Answer 22

reagent: NaOH (ethanol)
condition:

product: alkenes + water + NaX (X: halogen)
(this is an example of an elimination reaction)

Question 23

give the C-X bonds in ascending order

Answer 23

C-I (weakest) > C-Br, C-Cl, C-F (strongest)

Question 24

Give the condition and reagent of the reaction when CN (in ethanol) is added to halogenoalkanes. What is the product formed?

Answer 24

reagent: KCN (in ethanol)
condition: heat under reflux

product: nitrile (with an addition of one carbon atom)

Question 25

Give the condition and reagent of the reaction when NH3 in ethanol) is added to halogenoalkanes. What is the product formed?

Answer 25

reagent: NH3 (in excess) condition: NH3 should be dissolved in ethanol, carried out under pressure product: amine

Question 26

why is ammonia added in excess when halogenoalkanes are substituted with NH3?

Answer 26

so that we don’t get a mixture of amine products. because the amine will start to act as a nucleophile itself and will attack the halogenoalkane molecules forming secondary amines.

Question 27

describe SN2 mechanism

Answer 27

1. primary halogenoalkane 2. forms intermediate with 5 bonds 1. 1 step reaction

Question 28

describe SN1 mechanism

Answer 28

1. tertiary halogenoalkane | 2. 2 step reaction

Question 29

chap 17: | Give the conditions and reagent of the reaction when a halogen halide is added to alcohol. What is the product formed?

Answer 29

reagent: HX condition: product: H2O + halogenoalkane

Question 30

Give the reagent of the reaction when a sodium metal is added to alcohol. What is the product formed?

Answer 30

reagent: Na product: sodium alkoxide + hydrogen the longer the chain, the less vigorous the reaction

Question 31

Give the conditions and reagent of the reaction when a carboxylic acid is added to alcohol. What is the product formed?

Answer 31

reagent: carboxylic acid conditions: heat under reflux, strong acid catalyst (concentrated H2SO4) product: ester + H2O

Question 32

Give the conditions of the reaction when an alcohol is dehydrated. What is the product formed?

Answer 32

conditions: Al2O3 as catalyst product: alkene + H2O

Question 33

Give the conditions and reagent of the oxidation of alcohol. What is the product formed?

Answer 33

reagent: K2Cr2O7 (gives orange solution which turned green when alcohol is oxidized) conditions: reaction needs to be heated and dilute sulfuric acid needs to be added product: 1. with tertiary alcohol: no oxidation takes place 2. with secondary alcohol: ketone is formed 3. with primary alcohol: aldehyde is formed which further oxidizes to carboxylic acid

Question 34

what are the ways to make carboxylic acid?

Answer 34

1. oxidation of primary alcohols 2. hot concentrated manganate is added to alkenes 3. hydrolysis of nitrile group (nitrile is refluxed with HCl (turn CN bond to COOH))

Question 35

how do you convert carboxylic acids to their corresponding primary alcohols? what are the reagents and conditions?

Answer 35

1. by reduction reagent: LiAlH4 condition: in dry ether at room temperature

Question 36

chap 18: | give the reagent and condition for oxidation of primary alcohol. what is the product formed?

Answer 36

reagent: K2Cr2O7 condition: acidified with H2SO4, heat the reaction mixture product: aldehyde + water

Question 37

give the reagent and condition for oxidation of secondary alcohol. what is the product formed?

Answer 37

reagent: K2Cr2O7 condition: acidified with H2SO4, reaction must be heated product: ketone + water

Question 38

give the reagents and conditions for the reduction of carbonyl compounds. what are the products formed?

Answer 38

reagent: NaBH4 / LiAlH4 condition for NaBH4: warming the solution condition for LiAlH4: to be carried out in dry ether reducing ketone give secondary alcohol reducing aldehyde gives primary alcohol

Question 39

what mechanism takes places with carbonyl compounds and what are the reagents needed?

Answer 39

nucleophilic addition by using HCN as reagent

Question 40

the nitrile group can be reduced to what compound? what are the reagents needed?

Answer 40

an amine | reagent: Na (ethanol)

Question 41

2,4-DNPH gives positive for ketone and aldehyde. what is observed?

Answer 41

orange ppt

Question 42

name two reagents which give positive for only aldehydes

Answer 42

tollens’ and fehling’s 1. tollens’ gives silver mirror 2. fehling’s gives red/orange ppt

Question 43

what group gives positive for reaction with tri-iodomethane and what is observed?

Answer 43

CH3CO, yellow ppt is observed

Question 44

what is the only aldehyde that gives negative for tri-iodomethane?

Answer 44

ethanal