2. Chemical Reactivity

Question 1

What is aniline?

Answer 1

Aniline is an organic compound consisting of a phenol group attached to an amino group

Question 2

What is an aromatic ring?

Answer 2

A cyclic, planar molecule with a ring of resonance bonds that exhibits more stability than other geometric or connective arrangements with the same set of atoms

Question 3

What is an aryl group?

Answer 3

A functional group derived from a simple aromatic ting compound where one hydrogen atom is removed from the ring

Question 4

What is benzene?

Answer 4

An organic chemical compound the chemical formula C6H6. Because of the cyclic continuous pi bond between the carbon atoms, benzene is classed as an aromatic hydrocarbon

Question 5

What is a carbocation?

Answer 5

An ion with a positively charged carbon atom

Question 6

What is a covalent bond?

Answer 6

A chemical bond that involves the sharing of electron pairs between atoms

Question 7

What are electrophiles?

Answer 7

A positive or neutral species having vacant orbitals that are attracted to an electron rich centre

Question 8

What is Huckel’s Rule?

Answer 8

A compound with a planar ring system and a delocalized π-system containing (4n + 2) π-electrons, where n is an integer. Include neutral molecules, anions and cations and is aromatic

Question 9

What is hybridisation?

Answer 9

When atomic orbitals combine to form a new atomic orbital

Question 10

What is Markovnikov’s Rule?

Answer 10

In additions of HX to alkenes, H adds to the carbon with the greater number of hydrogens

Question 11

What are nucleophiles?

Answer 11

A chemical species that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction

Question 12

What is nucleophilic substitution?

Answer 12

Any reaction in which one nucleophile is substituted for another

Question 13

What is the ortho position?

Answer 13

When the functional group is on the carbon adjacent to another carbon with a functional group

Question 14

What is a phenol?

Answer 14

A class of chemical compounds consisting of a -OH group bonded directly to an aromatic hydrocarbon group

Question 15

What is regioselective?

Answer 15

One direction of bond-forming or bond-breaking occurs in preference to all other directions

Question 16

What is resonance theory?

Answer 16

Theoryby which the actual normal state of a molecule is represented not by a single valence-bond structure but by a combination of several alternative distinct structures.

Question 17

What does stereoselective mean?

Answer 17

Reactions in which one stereoisomer is formed or destroyed in preference to all others that might be formed or destroyed

Question 18

What does the reaction mechanism describe?

Answer 18

The formation and breakage of bonds

Question 19

What makes a carbocation primary, secondary or tertiary?

Answer 19

Depends on the number of carbons bonded to the carbon bearing the positive charge

Question 20

Are carbocations Lewis acids or Lewis bases?

Answer 20

Lewis acids - they accept electron pairs

Question 21

What types of carbocations are very stable?

Answer 21

secondary and tertiary

Question 22

What types of carbocations are never observed?

Answer 22

Methyl and primary

Question 23

True or False: Benzene is a planar molecule

Answer 23

True

Question 24

What special characteristic associated with planar ring systems allows for aromacity?

Answer 24

Delocalised p-orbital system

Question 25

What are the criteria for Huckel’s rule?

Answer 25

A ring must:

1. Have one 2p orbital on each of its atoms
2. Be planar, or almost planar, so that there is overlap between all 2p orbitals
3. Have 2, 6, 10, 14, 18 and so on π electrons in the cyclic arrangement of 2p orbitals

Question 26

Why is phenol more acidic than aliphatic alcohols?

Answer 26

Because the phenoxide ion is delocalised over the whole aromatic ring so it is very easy to remove the H ion

Question 27

How do you name an amine?

Answer 27

Replace the suffix -e of the parent alkane with -amine

Question 28

Are amines acidic or basic?

Answer 28

Basic

Question 29

All acceptable electron redistrobutions (bond break/make) must:

Answer 29

1. Have the same number of valence electrons
2. Obey the rules of covalent bonding
3. Differ only in distribution of valence electrons
4. Have the same number of paired and unpaired electrons
5. Have a charge balance following redistribution

Question 30

What determines whether an alcohol is primary, secondary or tertiary?

Answer 30

The number of carbons attached to the carbon attached to the -OH group.
1 carbon = primary
2 carbons = secondary
3 carbons = tertiary

Question 31

How is an alcohol converted into an alkyl halide?

Answer 31

Substitution of halogen for -OH

Question 32

What are the most common reagents for the conversions of alcohol to alkyl halide?

Answer 32

The halogen acids (i.e. HCl, HF etc.) and Thionyl chloride (SOCl2)

Question 33

Which type of alcohol (primary, secondary, tertiary) is very reactive with the halogen acids?

Answer 33

Tertiary

Question 34

What do primary alcohols oxidise to?

Answer 34

Aldehydes or carboxylic acids

Question 35

What do secondary alcohols oxidise to?

Answer 35

Ketones

Question 36

What do tertiary alcohols oxidise to?

Answer 36

They don’t, they are resistant to oxidation

Question 37

Why is benzene more stable than the triene model suggests?

Answer 37

The resonance energy makes benzene stronger than expected

Question 38

For a phenol, which positions on the molecule are negatively charged?

Answer 38

The -OH group pushes electron density onto the ortho- and para- positions

Question 39

Why are aromatic amines weaker bases than aliphatic ones?

Answer 39

The resonance interactions spreads the electron density therefore it is less able to pull a H ion away from another molecule

Question 40

what is the formula for chromic acid

Answer 40

H2CrO4