Organic Chemistry - Organic Compounds

Alkene

• Double carbon covalent bond

• Unsaturated hydrocarbons

• More reactive than alkanes due to carbon double bond

• useful starting materials for making other organic compounds/polymers

• can be part of addition reactions due to double bond

Functional Group

• group of atoms in a molecule that determines how it reacts

Bromine water test

• add orange bromine water to unknow alkane or alkene and shake

• if a saturated compound like alkane is present no reactions happen at it remains bright orange

• if a unsaturated compound like akene is present a reaction occurs and bromine water is decolourised (colourless)

Alkene DRAW

DRAW

Drawbacks of incomplete combustion

• smoky yellow flame

• less energy released than from complete combustion

• produced pollutants carbon + carbon monoxide + carbon dioxide + water

How do addition reactions work?

• two molecules combine to form a single molecule

• carbon carbon double bond breaks and opens up (meaning alkenes can be found in them)

• new atom is added to each carbon

Hydrogenation

- hydrogen reacts with an alkene in the presence of a catalyst

- which forms an alkane

- this get rid of double bond and adds an hydrogen to EACH carbon atom

Alcholos from alkenes

• react with steam in the presence of a catalyst

• (water is added across double bond and alcohol forms)

• breaks the double bond hydrogen goes on one side OH on the other

• then have to separate out the alcohol (OH goes to O - H)

• alcohol produced depends on the position of the C=C in the chain

Halogens - Alkenes

• chlorine/iodine/bromine

• double bond breaks

• halogen added to each carbon

• di - prefix normally

Polymerisation + conditions

• lots of small molecules (monomers)

• join together to form a large molecule (polymer)

• high temp/pressure

• presence of catalyst

How to draw repeating unit of polymer

• Draw the bonds of the monomer vertically up and down.

• draw to single bonded carbons instead of double bond

• fill in rest of the atoms

• branch out lines and put brackets in the middle

• write n on the outside on the right

Alcohols General Formula +DRAW first four

• C_nH_2n+1OH

• functional group - OH

• ends in -ol

• always show OH when writing general/structural

Properties of alcohols (ONLY FOR THE FIRST FOUR)

• Flammable - produce co2 and h2o

• souble in water and dissolve to forn neutral solutions with ph7 (longer chain less soluble)

• react with sodium to form hydrogen

• oxidised by oxidising agent to form carboxylic acids

Uses of alcohol

• Alcoholic drinks - ethanol mainly used

• Solvents -(methylated spirit - ethanol+chemicals which is posionous to drink so purple dye added)/perfumes

• Fuels - ethanol used as a fuel in spirit burners

Ethanol + 4 Uses

• C₂H₅OH

• Chemical feedstock to produce other chemicals

• Solvent/Fuel? Alcoholic drinks

Hydration of ethene

• Addition react as water is being added to ethene

• high temperature 300'C

• 6-70 atm

• phosphoric acid catalyst H₃PO₄

• ethene+steam—> ethanol

Pros/cons of hydration

• 100% atom economy as pure ethanol due to one product

• Ethene/Reaction is cheap/efficient

• however it is non renewable resource made from crude oil

• requries catalyst

• high cost for process

Fermentation of glucose for ethanol

• anaerobic respiration of sugar by yeast cells

• carried out in fermentation tanks requires yeast cells (with naturally occuring enzymes) to catalyse the reaction

• glucose for yeast to respire

• anaerobic conditions

• 30-40 degrees celsius (optimum temp)

• glucose—>ethanol+carbon dioxide

Pros/Cons of fermentation

• glucose is a renewable resource and cant run out (yeast is easy to grow)

• slow process

• not pure ethanol need to undergo fractional distilltion

• batch process

Carboxylic acid + DRAW

• COOH functional group

• end in -anoic acid

• double bond with lone oxygen atom and single bond with an oxygen atom in an OH group

• show COOH clearly in formulas

Carboxylic acids with water

• dissolve in water but dont complete ionise and release H+ ions

• form weak acids

• higher ph (less acidic) that aqueous solutions of strong acids with the same concentration

Carboxylic acids with carboonates

• produce carbon dioxide

• a salt

• water

• NAME BY : adding -anoate to the end eg. Sodium Butanoate

Esters

• COO functional group

• Can be called an ester linkage as the link the carboxylic acid and alcohol

• alcohol + carboxylic aic —> ester + water (in presence of strong acid catalyst) conc H₂SO₄

• used in perfumed because they are volatile/food flavourings

• have a sweet and fruity smell

Ethyl ethanoate

Condensation polymerisation

• monomers form to create polymer releasing small by products such as water

• two different monomers with two different functional groups

• one monomer with two functional groups

Polyesters

• diol+dicarboxylic acid —> polyester + water

Formation of condensation polymer

• dicarboxylic acid (carboxylicc acid with 2COOH groups) gives over its OH

• diol (alcohol with two oh groups) gives away its H

• this forms one water molecules

• the leftover carbon then joints up to the diols oxygen and forms and ester link

• repeat this to get 2nH20

Differnces between condensation and additional polymerisation

• in addition only one mononer type containing a C=C bond

• in condition there are two monomer types each containting two of same function group or one with two different groups

• in addition only one product the polymer is formed

• in condensation polymer and small molecule is formed

• in additional the repeating unit is a hydrocarbon

• whereras in condesation has an ester linkage

• addtion produced from alkene whereas polyester from a dicarboxylic acid and diol/alcohol

Amino Acids

• two function groups in one molecule

• Amino Group NH2

• Carboxyl group (COOH)

• can form polypeptides via condensation polymerisation

Proteins

• one or more long chain of polypeptides

• fold up to form protein

DNA

• deoxyribosenucleic acid

• double helix of two polynucleotides

• made of four different monomers

Nucleotide

• phosphate backbone

• deoxyribose sugar

• nitrogenous base

• adenosine,thymine,guanine,cytosine

Sugars

• small moleucles containing carbon,oxygen,hydrogen

• can form carbohydrate polymers via polymerisation reactions

• polyerms such as starch and cellulose

Incomplete combustion of alkanes

• Combustion without sufficient oxygen to react completely

• alkene + oxygen → carbon monoxide + carbon dioxide + water

What do functional groups usually determine?

• Determine how organic compounds react

• eg. Alkene C=C makes it more reactive than alkanes

Harmful products of incomplete combustion

• Carbon

• Carbon Monoxide

• Unburnt hydrocarbons

How to draw addition reactions for alkanes

• Always turn double bond to single bond

• Hydrogenation - Add tow hydrogens so it forms alkane

• Steam - Add OH but position matters

• Halogens - Add the diatomic molecule to the alkene

After addition reaction with alkene what must be done

• Fractional distillation

• To separate water and alcohol

Bromine water example of reaction with halogen

• alkene + bromine

• shake

• causes dibromo -

• causing orange colour to disappear (colourless)

• this is because C=C reactive so reacts with bromine

Why are alkenes unsaturated compared to alkanes?

Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.

What does MS 5b mean in AQA GCSE Chemistry?

• MS = Mathematical Skill

• You must be able to visualise 3D molecules

• Draw 2D representations (displayed formulae)

• Interpret structural diagrams

• Convert between molecular, structural and displayed formulae

• Understand molecules are 3D even when drawn in 2D

Monomer

• Small repeating units that joint together to form a larger molecule

• Know as a Polymer

Polymer

• Larger molecule formed from lots of smaller molecules (monomers)

Polymerisation

• Process by which lots of small molecules (monomers) join together to form a large molecule (polymer)

Addition Polymers

• Formed from unsaturated monomers (double bonds) like alkenes

How do you name polymers

• Monomer name in brackets and the phrase “poly” in front of it

• Polymer of Ethene would be “poly(ethene)”

How do addition polymers form?

• Carbon carbon double bonds within the monomers break

• Allowing two monomer molecules to bond to each other

A - Polymer
B - Repeating Unit

C - Monomer

Repeating unit differences

• n is on the left

• double bond is still present

Longer molecules addition polymerisation how to draw repeating unit?

• Draw the repeating unti part with the carbon

• Take out the carbon double bond

• Then for missing part simplify it

• Add to the repeating unit (vertically) and connect carbon to carbon not hydrogen

• then do the brackets branch out and n on the right

How can alkenes be used to make polymers?

Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation.

What happens in addition polytmerisaiton?

In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers).

Repeating unit vs monomer in addition polymerisation reactions?

In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.

Why are alcohols used as solvents?

• Dissolve lots of different substances including hydrocarbons oils and fats

Alcohol Table DRAW

Why are temperatures of 30-40 degrees used when making ethanol by fermentation?

• catalysed by enzymes and 30-40 degrees is the optimum temperature for them to function at

What is fermentation?

Fermentation is the anaerobic respiration of sugars by yeast cells to produce ethanol and carbon dioxide.

How is ethanol made from ethene?

Ethene is reacted with steam (gaseous water) at a high temperature, high pressure, and with a phosphoric acid catalyst.

How are esters formed?

An ester is made by reacting a carboxylic acid and an alcohol in the presence of an acid catalyst (such as sulfuric acid).

Formation of ester steps

• the carboxylic acid loses its OH group,

• the alcohol loses the H from its OH group.

• These then combine to form water (H₂O).

What does biodegradable mean?

• Substance that can be broken down by naturally occuring polymers

• only condensation polymers are biodegradeable

Requirements for condensation polymerisation

• Condensation polymerisation involves monomers with two functional groups

• 2 different function groups overall

• When these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions.

Three elements that make up carbohyrdates

• hydrogen

• carbon

• oxygen

2 Different functional groups in all amino acids

• Amino group (NH2)

• Carboxyl Group (COOH)

• Different amino acids can be combined in the same chain to produce proteins.

How are polypeptides made

mino acids react by condensation polymerisation to produce polypeptides.

• one or more long chains of polypeptides are know as proteins

Sugar Made of?

• Carbon

• Oxygen

• Hydrogen

• Sugars can form carbohydrate polymers known as polysaccharides via polymerisation reactions

Examples of Naturally Occurring Polymers

• Proteins

• DNA

• Poly Peptides

Imporatnace and function of DNA

• DNA (deoxyribonucleic acid) is a large molecule essential for life

• DNA encodes genetic instructions for the development and functioning of living organisms and viruses.

• Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix.

What are the four naturally occurring polymers essential for life?

• DNA - Nucleotides

• Protein - Amino Acids

• Starch - Glucose

• Carbohydrates - Simple sugars (Glucose)

How does amino acids form poly peptides

• Two function groups allow adjacent amino acids to join together through condensation reactions

• OH and H taken out to form water

• Carbon and nitrogen bonds together (amide link/bond/peptide bond)

• n before polymer n around repeating unit n before water