organic chemistry (excluding polymers)

cracking definition

the process where big oil molecules are broken up into small molecules under high temperature and using porous ceramic pot as a catalyst

what is produced during cracking

1. alkenes are always formed

2. other products can be alkanes, hydrogen or both

what are requirements for cracking

1. high temperature

2. cat: porous ceramic pot

how to manufacture alcohol

1. catalytic adding of steam to alkene (addition)

   1. Alkene + H2O → alcohol

2. by fermentation of sugar with yeast

   1. C6H12O6 → 2 C2H5OH + 2CO2

requirements of catalytic adding of steam to alkene

1. Cat: H3PO4

2. 300ºc

3. 65 atm

requirements of fermentation of sugar with yeast to alcohol

1. 37ºc

2. yeast (anaerobic respiration)

how to manufacture carboxylic acid

oxidation of alcohols

1. atmospheric oxygen oxidising alcohol

   1. C2H5OH + O2 —bacteria→ CH3COOH + H2O

2. using oxidising agents (acidified KMnO4 solution or acidified K2Cr2O7 solution)

   1. C2H5OH + 2[O] → CH3COOH + H2O

what is required for oxidation of alcohol to form carboxylic acids by the action of atmospheric oxygen

bacteria

solubility of alkanes and alkenes

insoluble in water, but soluble in organic solvents

what reactions does alkanes undergo and under what requirements

1. combustion (alkane + O2 → CO2 + H2O)

   1. incomplete combustion: alkane + O2 → CO + H2O

   2. little of oxygen: alkane + O2 → C + H2O

2. substitution reactions

   1. one substitution at a time

   2. REQUIRE LIGHT

   3. alkanes will NOT react with aqueous bromine

what are alkanes used for

fuel for cooking, generating electricity etc

what reactions do alkenes participate in

1. combustion alkene + O2 → CO2 + H2O

2. addition reactions

   1. alkene + H2 → alkane (Ni, 200ºc)

   2. alkene + halogen → substituted alkane

   3. alkene + H2O → alcohol

   4. addition polymerisation

what Is required for the alkene + H2 reaction?

Ni catalyst, 200ºc

what are the requirements for alkene + halogen reaction?

no requirements

spontaneous reaction

what are the requirements for alkene + H2O → alcohol reactions?

H3PO4 catalyst, 300ºc, 65 atm

how to test alkanes versus alkene

1. use aqueous bromine

2. alkenes decolourises reddish brown aqueous bromine

what are alkenes used for

1. make plastics, ethanol (an important solvent)

2. 1,2-dibromoethane is added to petrol to remove lead from car engines

solubility of alcohols and carboxylic acids

soluble in water

smell of alcohol and carboxylic acids

sharp-smelling (alcohol)

sour (acids)

what reactions do alcohols take place in

1. combustion with oxygen to form carbon dioxide and water

2. dehydration (-H2O) to form alkene

   1. require concentrated sulphuric acid as a dehydrating agent

3. oxidation to form carboxylic acid

how are carboxylic acids prepared from alcohols?

oxidation of alcohols

1. by the action of atmospheric oxygen

   1. alcohol + O2 → alcohol + H2O

2. using an oxidising agent

   1. alcohol + 2[O] → alcohol + H2O

how to test for alcohol?

colour change in oxidising agent

what are alcohols used for

• solvent for paints, varnishes

• used as fuel

• alcoholic drinks

• to make ethnic acid for preserving food and esters

what are reactions that carboxylic acids partake in

1. reactions with base, metal and carbonates as a WEAK ACIDS

2. esterification (dehydration)

3. reaction with amines to form amines (dehydration)

how to indicate ionisation of carboxylic acids?

acid ⇄ CnH(2n+1)COO- + H+

uses for carboxylic acids

1. ethanoic acid is used as a vinegar to flavour food

2. make esters

3. used as solvents for paints, glues and varnishes

solubility of esters

insoluble in water but soluble in organic solvents

smell of esters

sweet smelling

naming of esters

_______yl _______noate

(alcohol) (acid)

how is H2O removed from acid + alcohol in the making of an ester

acid — CO / OH and H / O— alcohol

petroleum is a mixture?

yeah

what is a homologous series

a group of organic compounds all having the same general formula and each differing from the next by a —CH2— group of atoms

what is a substitution reaction

a reaction in which one or more atoms of an organic compound are replaced with one or more other atoms

what is an addition reaction

a reaction is one in which two or more molecules react to give only one product. there are no other by products

why is the bigger organic molecule has a higher melting point than smaller organic molecules

1. explain why its bigger (more H atoms? etc)

2. bigger modules have stronger intermolecular forces of attraction than vegetable oil

3. more energy needs to be absorbed to overcome these forces of attraction

4. (with this higher melting point, bigger molecules often is a solid while smaller molecules is a liquid at room temperature)