Organic 1

Question 1

Conjugated System

Answer 1

a system of coplanar, overlapping (adjacent) π orbitals

Question 2

Brønsted definition

Answer 2

Acid: proton donor
Base: proton acceptor

Question 3

Lewis definition

Answer 3

Acid: lone pair acceptor
Base: lone pair donor

Question 4

R-stereochemistry

Answer 4

clockwise movement of priority groups

Question 5

S-stereochemistry

Answer 5

anti-clockwise movement of priority groups

Question 6

Chiral centre

Answer 6

geometric property of a rigid molecule of being non-superimposable on its mirror image

Question 7

Pro-chiral

Answer 7

when a molecule can have its mirror plane broken to create a chiral centre in a single step

Question 8

Constitutional isomers

Answer 8

same atoms, but different connectivities

Question 9

Configurational isomers

Answer 9

molecules have identical constitution but they have different configurations (spatial arrangements)

Question 10

Enantiomers

Answer 10

• have opposite absolute configurations
• same chemical properties towards achiral reagents
• same physical properties in achiral environments
• rotate plane of polaries light in opposite directions to the same extent
• react differently to other chiral species
• can be separated by resolution

Question 11

Diastereoisomers

Answer 11

• May be chiral or achiral
• Differ at one or more but not all chiral centres
• they have different chemical and physical properties

Question 12

Conformational isomers

Answer 12

they have the same bond connectivity and configuration but different spatial arrangements of atoms

Question 13

Factors that affect acidity and basicity

Answer 13

• the strength of the H-A bond
• the stability of the conjugate base
• the solvent/ solvation effects

Question 14

What are requirements for efficient reactions?

Answer 14

• similar energies of key orbitals (high energy Nu HOMO/ low energy electrophile LUMO)
• good alignment (coplanar) of the HOMO-LUMO – efficient orbital overlap

Question 15

Characteristics of hard nucleophiles and bases

Answer 15

• high charge density
• low energy HOMO
• X- is basic
• Like to attack H+ and C=O

e.g. RO- , NH ₂ - RLi

Question 16

Characteristics of soft nucleophiles and bases

Answer 16

• low charge density
• high energy HOMO
• X- is not basic
• Like to attack sp3 C

e.g. RS-, I-, R ₃ P

Question 17

Conditions for organometallic reactions

Answer 17

• low temperature (they’re very reactive)
• use aprotic solvents (THF) as protic solvents such as water have acidic protons
• done in a dry, inert atmosphere of nitrogen or argon (very reactive with oxygen)

Question 18

Are organometallics acidic or basic?

Answer 18

Very basic