Week 11 - Organic Reactions

Question 1

4 types of organic reactions

Answer 1

substitution, addition, elimination, rearrangement

Question 2

substitution

Answer 2

one group replaces another - characteristic of saturated compounds and aromatic compounds

Question 3

addition

Answer 3

reagent adds to substrate (two molecules become one) - characteristic of pi bonds/unsaturated bonds

Question 4

elimination

Answer 4

one molecule becomes two or more - main reaction in preparation of pi bonds/unsaturated bonds

Question 5

rearrangement

Answer 5

reorganization of a molecule - characteristic of reactive intermediates

Question 6

exothermic

Answer 6

PE of products is lower than that of reactants

Question 7

endothermic

Answer 7

PE of products is higher than that of reactants

Question 8

two ways to break bonds

Answer 8

homolysis, heterolysis (homolytic, heterolytic cleavage/breaking)

Question 9

homolysis

Answer 9

formation of radicals - neutral species that carry an unpaired electron (1 electron in each move)

Question 10

heterolysis

Answer 10

formation of ions - complete transfer of electrons to one atom (2 electrons in each move)

Question 11

carbocation vs carbanion

Answer 11

carbocation - electron deficient carbon (+ve charge)
carbanion - electron rich carbon (-ve charge)

Question 12

nucleophiles

Answer 12

electron-rich species (seeking a positive center - nucleus)

Question 13

electrophiles

Answer 13

electron deficient species (want electrons to complete octet)

Question 14

in organic reactions…

Answer 14

nucleophile ‘attacks’ electrophile (draw arrow in direction of attack - shows movement of electrons)

Question 15

nucleophiles can be…

Answer 15

1. anion
2. neutral molecule with a lone pair
3. molecules with pi-bonding electrons

Question 16

strength of nucleophiles

Answer 16

• the more basic a compounds is, the better it is as a nucleophile
• a -vely charged n.phile is stronger than its conjugate acid
• bottom left are the best n.philes

Question 17

hydrogenation

Answer 17

addition of molecular hydrogen (usually in the presence of a catalyst)

Question 18

Markonikov’s rule

Answer 18

hydrogen adds to the carbon in the double bond that has more hydrogen atoms, and the halogen adds to the carbon with fewer hydrogen atoms