Block 4; Functional Group Chemistry

Question 1

What are ortho/para directors that are strongly activating?

Answer 1

• OH
• OR
• NH2
• NR2

Question 2

What are ortho/para weakly activating directors?

Answer 2

CH3- alkyl

Question 3

What are ortho/para deactivating directors?

Answer 3

-X (F, Cl, Br, I)

Question 4

What do oxygen, nitrogen and halogens all have in common?

Answer 4

Unshared electron pairs that can be donated into the aromatic rings (by resonance)

Question 5

What are strongly deactivating meta directors?

Answer 5

NO2

Question 6

What are moderately deactivating meta directors?

Answer 6

Aldehydes, ketones, nitriles

Question 7

What do all meta directors have in common?

Answer 7

They have a multiple bind to the atom that is bonded to the aromatic ring sp2 carbon

Question 8

What do activating directors do?

Answer 8

Speed up reactions

Question 9

What do deactivating directors do?

Answer 9

Slow down reactions

Question 10

What does the favoured ortho/meta substitution have?

Answer 10

More resonance contributors

Question 11

What forms a race mic mixture of 50:50 S and R?

Answer 11

If an alkyl halide with a chiral centre is prepared

Question 12

What are good leaving groups (weak bases)?

Answer 12

Cl
Br
I

Question 13

What are poor leaving groups (strong bases)?

Answer 13

H, NH2-, HO-, RO-

Question 14

What are the two mechanisms of alkyl halide substitution?

Answer 14

Sn1 unimolecular mechanism

Sn2 bimolecular mechanisms

Question 15

What types of alkyl halide is Sn1 favoured for?

Answer 15

3 (tertiary), (some secondary and benzylic halide) where intermediate carbonation from breaking the c-x bond is relatively stable

Question 16

Describe an SN1 reaction?

Answer 16

A substitution, by a nucleophile, where only one species in involved in the rate determining step (where the leaving group departs)

Question 17

Which enantiomer produces a racemic mixture in Sn1 substitution reactions for alkyl halides?

Answer 17

Both R and S

Question 18

Which alkyl halide substitution reaction is a 2 energy profile?

Answer 18

Sn1 mechanism

Question 19

What favours sn2 bimolecular mechanisms?

Answer 19

1 halides and some secondary halides

Question 20

What mechanism is concerted/synchronous?

Answer 20

Sn2 bimolecular mechanisms

Question 21

Describe SN2 reactions?

Answer 21

Substitution, by a nucleophile, with two species involved in the rate determining step

Question 22

Is there an intermediate carbonation in sn2 mechanisms?

Answer 22

No

Question 23

What happens when a chiral non-racemic secondary halide reacts via a Sn2 pathway?

Answer 23

A chiral, non-racemic (optically active) product results from the inversion of configuration

Question 24

Why is a primary halide favoured for SN2 reactions?

Answer 24

Because it’s not too crowded to have the transition state (body does Sn2 Chem)

Question 25

Two types of alkyl halide elimination reactions?

Answer 25

E1 unimolecular | E2 bimolecular

Question 26

What does E1 mechanisms favour?

Answer 26

Tertiary

Question 27

What happens if Sn1 and E1 compete?

Answer 27

Product mixtures are produced

Question 28

Does the zaitsev rule apply to E1 mechanisms?

Answer 28

Yes, where more than one Alkene can be formed

Question 29

What favours Elimination (E) over Sn (substitution)?

Answer 29

Stronger bases, higher temperatures and a non-nucleophilic solvent

Question 30

What are E2 mechanisms?

Answer 30

When the proton is removed (C=C bond formed), and the C-X bond is broken, all in a single concerted step

Question 31

What does E2 reactions require?

Answer 31

A strong base

Question 32

What do E2 reactions favour?

Answer 32

Tertiary

Question 33

When can E2 be observed in primary halides?

Answer 33

If product extends conjugation

Question 34

Examples of a weak nucleophilic neutral reagent?

Answer 34

H20, CH3OH, CH3CH2OH

Question 35

What are stronger nucleophiles with low basicity?

Answer 35

Cl, Br, I, CN-, CH3S-, CH3COO-

Question 36

What are stronger nucleophile, high basicity reagents?

Answer 36

HO-, CH3O-, CH3CH2O-, H3N, (CH3)3N, H2N

Question 37

Describe the reactions of alkyl halides 1,2,3 for weak nucleophile, neutral reagents?

Answer 37

Primary; SN2 Secondary; SN1 or SN2 Tertiary; Sn1 and E1

Question 38

Describe the alkyl halide reaction for 1,2,3 with a stronger nucleophile, low basicity reagent

Answer 38

Primary; SN2 Secondary; Sn2 Tertiary; Sn1 and E1

Question 39

Describe the alkyl halide of a stronger nucleophile, high basicity reagent for 1,2,3

Answer 39

Primary; Sn2 Secondary; Sn2 and E2 Tertiary; E 2

Question 40

What is a Holden attached to a sp2 carbon not susceptible to?

Answer 40

SN (so no reaction)

Question 41

What can Grignard reagents act as?

Answer 41

Carbon nucleophile

Question 42

What reagent is used in the catalytic dehydrogenation of alkanes (to alkenes)?

Answer 42

Pt/Pd, heat at 600C

Question 43

What reagent is used in the acid-catalysed dehydration of (removal of H2O from) alcohols? (To form alkene)

Answer 43

Concentrated H2SO4

Question 44

What reagent is used in the base promoted dehydrogenation of (removal of HX from) alkyl halides (to form alkene)?

Answer 44

KOH or NaOH

Question 45

What type of preparations usually form alkenes?

Answer 45

Elimination

Question 46

What reagent is used in the hydrogenation of alkenes?

Answer 46

H2/catalyst (e.g Pt)

Question 47

What stereochemistry does the hydrogenation of alkenes involve?

Answer 47

Syn

Question 48

What reagent does the halogenation of alkenes involve?

Answer 48

Br2, Cl2

Question 49

What sort of stereochemistry does the halogenation of alkenes occur in?

Answer 49

Anti-stereochemistry (trans)

Question 50

Which is more stable; secondary or primary carbocation?

Answer 50

Secondary