Intro to organic chem + isomerism

Question 1

Primary vs Secondary vs Tertiary (how to identify?)

Answer 1

Based on no. of alkyl groups bonded to the C bonded to the functional group

Question 2

Functional group isomerism examples

Answer 2

Aldehydes and ketones
Ethers and alchohols
Esters and Carboxylic acids

Question 3

Types of isomerism

Answer 3

Constitutional - chain, positional, functional group
Stereoisomerism - cis-trans, enatiomerism

Question 4

Why does cis-trans isomerism occur?

Answer 4

Free rotation restricted by presence of double bond, ring structure or steric factors

In Alkene, because of pi bond which restricts rotation about C=C double bond

Question 5

Stereoisomerism definition

Answer 5

same molecular and constitutional formulaw but different 3D arrangement

Question 6

Do cyclic alkenes experience cis trans?

Answer 6

No. 3-7 C in cis structure, 8 and above in trans structure because high ring strain

Question 7

Why can cis trans isomers be isolated as 2 different compounds?

Answer 7

Restricted rotation about the single bonds in the cyclic systems

Question 8

Chiral + Enatiomers definition/conditions

Answer 8

Chiral compound does not have an internal plane of symmetry nor a superimposable mirror image. Chiral molecule + non-superimposable mirror image form a pair of enatiomers

Question 9

Physical vs chemical properties of cis trans isomers

Answer 9

Chemical properties similar, not identical (react with same reagents but at different rates)
Physical properties different

Question 10

Racemic mixtures

Answer 10

Sample containing equal amounts of 2 enatiomers. Rotation of the 2 enatiomers are of the same extent but in opposite directions, causing no net effect on the plane-polarised light and hence optically inactive

Question 11

Empirical formula

Answer 11

Simplest ratio of atoms of dif elements

Question 12

Molecular formula

Answer 12

actual number of atoms of each element present in one molecule

Question 13

Constitutional (skeletal) fomula

Answer 13

shows how constituent atoms are joined together

Question 14

Displayed formula

Answer 14

shows arrangements of atoms and all the bonds between them

Question 15

Stereochemical formula

Answer 15

spatial arrrangement of the molecule in a 3d space

Question 16

functional group

Answer 16

an element/combination of elements responsible for the chemical reactions of an organic compound

Question 17

Homologous series

Answer 17

Family of compounds containing the same functional group but differing by a CH2 group between one member and the next

Question 18

Names and structures of all the dif functional groups

Answer 18

Hydrocarbons- alkanes, alkenes, alkynes, arenes

Hydroxyl- alchohol, phenol, ether

Halogen derivitives - halogenoalkanes, halogenoarenes

Carbonyls- aldehydes, ketones

Carboxylic acids and derivitives- carboxylic acid, ester, acyl chloride

Nitrogen compounds- amine, amides, nitriles, amino acids

Question 19

Saturated vs unsaturated compound

Answer 19

saturated: only single bonds
unsaturated: multiple bonds

Question 20

Explain hybridisation

Answer 20

One 2s electron is promoted to a 2p orbital, allows them to interact to form sp3, sp2 and sp bonds which are stronger and equal in length

Question 21

Why use hybridisation?

Answer 21

equal bond length
More effective orbital overlap since larger lobe is used –> stronger bonds compared to if s orbitals or p orbitals overlap

Question 22

sp, sp2 or sp3 strongest bond? Why?

Answer 22

sp. Highest degree of s character. Electrons held closer to the nucleus and shorter bond length–> stronger

Question 23

How to figure out which hybrisation?

Answer 23

No of molecules it is bonded to + no of LP
sum = 4, sp3
sum = 3, sp2
sum = 2, sp

Question 24

Types of organic reaction

Answer 24

Addition (formation of a pi bond)

Substitution (a group is replaced by another group of atoms)

Elimination (removal of atoms from 2 adjacent atoms (in one molecule) to form a pi bond)

Condensation (2 or more molecules combine to form a larger molecule and elminate a smaller molecule like water or HCl)

Hydrolysis: reaction with water, catalysed by acids/bases

Oxidation: gain O or lose H

Reduction: gain H or lose O

Question 25

Nucleophile

Answer 25

electron rich species capable of donating a LP of electrons to form a new bond

Question 26

Electrophile

Answer 26

electron deficient species capable of acceptingF a LP of electrons to form a new bond

Question 27

Free radical

Answer 27

highly reactive species with an unpaired electron

Question 28

Homolytic vs heterolytic fission

Answer 28

Homolysic fission –> 2 electrons split equally
Heterolytic fission –> both electrons move to one atom