organic chemistry

intramolecular forces and examples

intramolecular forces and examples

forces that hold atoms together within a molecule. Covalent bonding, ionic bonding, metallic bonding

intermolecular forces and examples

the forces that exist between molecules. London dispersion forces, dipole-dipole interactions, hydrogen bonding

Zaitsev's Rule

states that the major product of an elimination reaction will be the most stable

What makes a compound aromatic

its planar and cyclic, every atom must be conjugated, the molecule must have [4n+2] pi electrons

meso compound

a molecule that has a chiral centres but also has an internal plane of symmetry. they are optically inactive

racemic mixture

an equimolar mixture of two pure enantiomers that is optically inactive

hydrophobicity with examples

"water hating". molecules will repel water and will not undergo H- bonding. Organic alkyl groups -CH3, -C2H5

Hydrophilicity with examples

"water loving". Molecules will attract water and undergo H-bonding. Hydroxyl group -OH

Solubility of Alkenes

Density increases with increasing molecular weight. They are less dense than water = it separates out into 2 distinct layers . Alkene on top and water on the bottom

solubility of alkenes example

Gulf of Mexico 2010, Mauritius 2020 oil spills

4 types of electrophilic aromatic substitution reactions do benzene and aromatic compounds undergo

1. Halogenation 2. Nitration 3.Sulphonation 4. Freidel-Crafts reaction (alkylation/acylation)

Why are benzene rings so stable?

delocalisation of its pi electrons around the ring and the overlap of its p orbitals. 6 pi electrons delocalised around the ring in the molecular orbitals above and below it.

chiral carbon

any compound that contains a tetrahedral carbon atom with 4 different substituents attached

Enantiomers

two stereoisomers that contain asymmetric carbon atoms. They are chiral and are non-superimposable mirror images of each other

Diastereomers

they are not enantiomers and are not mirror images of each other

why are low weight alcohols soluble in water

they are generally 3 carbons or less and are soluble as they can still undergo H-bonding due to their hydroxyl group

why are high weight alcohols not soluble in water

they contain a large non-polar C backbone relative to the polar O-H group

Nucleophile with example

molecule or ion that donates a pair of electrons to another molecule or ion to form a new covalent bond. HO- (minus)

leaving group with example

group of atoms that can be expelled from a molecule, taking both electron bonds with them. They are usually anion (after it has left). CL-, Br-, I-

Resonance Energy

the difference in energy between a stabilised resonance hybrid and its lowest energy resonance form

how would you estimate the resonance energy of benzene

by examining the heats of hydrogenation between cyclohexane and benzene

strongest type of intermolecular forces

hydrogen bonding

why is hydrogen bonding the strongest

it is a particular dipole-dipole interactions, it occur between molecules containing h-bonded to fluorine, oxygen, or nitrogen atoms. it is attached to the lone pair of another molecules O,N, or F atoms

Redox Reaction

reactions in which oxidation and reduction of a compound or molecule takes place

example of redox reaction

sodium borohydride reduction of benzophenone

condensation reaction

reaction in which two smaller molecules combine to form a larger molecule with the loss of water or another small molecule

Example of a condensation reaction

esterification reaction or saponification or formation of disaccharides

what factors effect the Freidel-Craft Alkylation of aromatic compounds

1. reaction is only partial with stable tertiary carbocations. 2. No reaction occurs if the aromatic ring contains strong electron withdrawing group as a substituent.

strong electron withdrawing groups example

ketone, aldehydes, carboxylic acids, esters, amides, sulphonic acid, nitrogen dioxide, trifluoromethyl or trichloromethyl groups and nitro groups

describe the mechanism of electrophilic addition reactions of haloalkanes

elimination reactions remove a halogen and H atom from a haloalkane to from a new C=C bond. The product of the reaction is an alkene

describe the mechanism of substitution reactions of haloalkanes

remove a halogen atom from a haloalkane and replace it by a nucleophile

Zaitsevs limitations

unsaturated haloalkane (double bond), or benzene ring. Bulky base sterically hinders b carbon

what does b carbon have

contains smaller number of h atoms which would give the most stable product