intro to organic chem

Question 1

what is the difference between an alipathic, alicyclic and an aromatic compound?

Answer 1

alipathic - compound with open chains of carbon atoms (may be branched or unbranched, contains single/double/triple/combi of these)
alicyclic - compound with closed rings of carbon atoms eg cycloalkanes
aromatic - compound containing at least 1 aromatic system, eg benzene ring

Question 2

what is a substitution reaction?

Answer 2

when an atom or group of atoms replaces another atom or group in a molecule.
eg: CH3CH2Cl + OH- -> CH3CH2(OH) + Cl-

Question 3

what is an addition reaction?

Answer 3

when an organic molecule, usually containing a double bond, reacts with another molecule to give only one product. the π bond of the double bond breaks to form 2 σ bonds.
eg: CH2=CH2 + HCl -> CH3CH2Cl

addition is the opposite of elimination

Question 4

what is an elimination reaction?

Answer 4

when a double bond is formed with the removal of a molecule from adjacent carbon atoms.
eg CH3CH2Cl -> CH2=CH2 + HCl

elimination is the opposite of addition

Question 5

what is a condensation reaction?

Answer 5

when 2 molecules come together to form a bigger molecule, with the elimination of a small molecule (NEED NOT BE WATER)
NOT the same as elimination, which requires the formation of a new double bond
eg: CH3CH2COOH + CH3OH -> CH3CH2COOCH3 + H2O

the opposite of hydrolysis

Question 6

what is a hydrolysis reaction?

Answer 6

when a molecule is split into two by the action of water, often catalysed by dilute acids or dilute alkalis
eg: CH3CH2COOCH3 + H2O -> CH3CH2COOH + CH3OH

the opposite of condensation

Question 7

what is an oxidation reaction?

Answer 7

when O atoms are added to the molecule OR when H atoms are removed from the molecule
oxidation number of an atom in the functional group must increase

opposite of reduction

Question 8

what is a reduction reaction?

Answer 8

when O atoms are removed from the molecule OR when H atoms are added to the molecule
oxidation number of an atom in the functional group must decrease

opposite of oxidation

Question 9

what is homolytic fission?

Answer 9

breaking of a covalent bond where the bonding pair of electrons are given equally to each atom.
results in the formation of free radicals, that readily form bonds with other atoms or molecules

Question 10

what is heterolytic fission?

Answer 10

breaking of a ovalent bond where both bonding electrons are given to one of the atoms, usually the more electronegative atom.
results in the formation of ions, eg carbocations

Question 11

what is an electrophile?

Answer 11

an electrophile is a species that accepts an electron pair to form a covalent bond in a reaction. it is electron-deficient as it has a positively charged centre OR an induced/permanent positive charge

Question 12

what is a nucleophile?

Answer 12

a nucleophile is a species that donates an electron pair to form a covalent bond in a reaction. it is electron-rich and possesses electrons that can be shared, such as lone pairs of electrons or π bond

Question 13

what are factors affecting organic reactions?

Answer 13

1. inductive effect
2. delocalisation
3. steric effect

Question 14

what is inductive effect?

Answer 14

inductive effect arises from the polarisation of electron density in a bond due to the electronegativity of nearby atoms.
inductive effect gets weaker with distance

Question 15

what is delocalisation?

Answer 15

delocalisation occcurs when p orbitals on 3 or more adjacent atoms overlap, forming a π electron cloud in which all the electrons from all the overlapping p orbitals can be found. this stabilises compounds

Question 16

what is steric effect?

Answer 16

steric effect results from the repulsion between electron clouds of groups or substituents, depending on their size and number.
molecules with bulky substituents crowded around their reactive sites would hinder the approach of the other reactant for an effective collision. when steric effect hinders the rate of reaction, it is called steric hindrance. the larger the groups & the greater the number of groups crowding around the site of reaction, the greater the steric hindrance