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Level 3
Organic Chemistry
* Variation in the way organic molecules are drawn.
* Structural isomers have the same atoms but are arranged in different ways
* Isomers that occur in assymetrical alkene molecules where the double bond restricts rotation around the carbon atoms. The carbons on either side of the double bond are required to have 2 different groups or atoms attached to them
*When H atoms are on the same side of their respective carbons, we call it a cis molecule
*When H atoms are on different sides, it forms a trans molecule
*Optical isomers exist in nature in equal quantities. It is a an isomer that forms when molecules are mirror-images of each other and are non-superimposable
*Molecules have a chiral (central) carbon that is connected to 4 different groups.
*Optical isomers can be distinguished with plane polarised light as each isomer will deflect light in opposite directions
*End in -ane
*Non-Polar = Insoluble in water
* Low melting and boiling points as they have weak intermolecular forces
* Small groups (up to 4 carbons) are gases at room temperature
Bromine water is used to test for alkanes.
Orange Bromine water will only turn colourless in the presence of UV light
Alkane + Bromine ==> Haloalkane
Alkane + Halogen ==> Haloalkane
*Contains halogens in their molecules
*Halogens are either F, Cl, Br, I (Group 17 atoms)
Addition: Alkene + Halogen ==> Haloalkane
Addition: Alkene + Halogen ==> Haloalkane
Addition: Alkene + Hydrogen halide ==> Haloalkane
Substitution: Alcohol + PCl3/SOCl2 ==> Haloalkane
Substitution: Haloalkane + KOH(aq) ==> Alcohol
In the reaction:
Propan-ene + HBr, we have two possible products that can form:
One product will be in more abundance than the other. This is called the MAJOR product and the other one is called the MINOR product.
In order to know which one is which, we follow MARKOVIKOV'S RULE: The rich gets richer.
MAJOR PRODUCT:
The carbon with the most Hydrogens attached to it, will get the hydrogen from the HBr, and the other carbon will get the Br.
MINOR PRODUCT:
The carbon with the least amount of Hydrogens attached to it, will get the hydrogen from HBr, and the other carbon will get the Br
Opposite of Markovnikov's rule:
The poor gets poorer
If atoms in an asymmetrical molecule get removed from a molecule to form an alkene, atoms can be removed from either side of the double bond and will therefore result in two possible products forming.
The majority of the product that forms will follow Saytzeff's rule- the carbon with the least amount of Hydrogens attached to it, will lose another hydrogen.
*Named by using -ene (and the
number of the carbon that
contains the double bond )as a
suffix eg. But-2-ene
* Non-polar so insoluble in water
* Relatively low melting and boiling points due to weak intermolecular forces
*UNSATURATED molecule: Very reactive as the double bond will easily break to bond to whatever it's added to.
Addition: Alkene + Hydrogen halide ==> Haloalkane
Addition: Alkene + H20/H ==> Alcohol
Addition: Alkene + Alkene ==> Polymer
Addition: Alkene + Hydrogen gas ==> Alkane
Elimination: Alcohol + H2SO4 ==> Alkene
Opposite of Markovnikov's rule:
The poor gets poorer
If atoms in an asymmetrical molecule get removed from a molecule to form an alkene, atoms can be removed from either side of the double bond and will therefore result in two possible products forming.
The majority of the product that forms will follow Saytzeff's rule- the carbon with the least amount of Hydrogens attached to it, will lose another hydrogen.
In the reaction:
Propan-ene + HBr, we have two possible products that can form:
One product will be in more abundance than the other. This is called the MAJOR product and the other one is called the MINOR product.
In order to know which one is which, we follow MARKOVIKOV'S RULE: The rich gets richer.
MAJOR PRODUCT:
The carbon with the most Hydrogens attached to it, will get the hydrogen from the HBr, and the other carbon will get the Br.
MINOR PRODUCT:
The carbon with the least amount of Hydrogens attached to it, will get the hydrogen from HBr, and the other carbon will get the Br
*The single C-C bond in alkanes allows for rotation of the groups of atoms but in an alkene, the double bond prevents rotation. It is therefore possible for molecules to have the same molecular formula and the same name, to have geometric isomers.
*Geometric isomers is where two different groups/atoms that are bonded to each C atom of the double bond, occupy different positions in space
*Orange/Brown bromine water instantly changes to colourless when an alkene is added to it.
*This happens because the double bond is unsaturated and readily binds to the bromine to form a haloalkane.
*This is different from Alkanes as alkanes will only turn bromine water colourless in the presence of UV light
*Process involved in linking many alkene molecules to form long chains.
*A monomer is a single molecule, and they link together to form a polymer
*Polymers are named after their monomers and a poly- prefix. Eg. Polyethene is made up of ethene molecules that got connected
In the reaction:
Propan-ene + HBr, we have two possible products that can form:
One product will be in more abundance than the other. This is called the MAJOR product and the other one is called the MINOR product.
In order to know which one is which, we follow MARKOVIKOV'S RULE: The rich gets richer.
MAJOR PRODUCT:
The carbon with the most Hydrogens attached to it, will get the hydrogen from the HBr, and the other carbon will get the Br.
MINOR PRODUCT:
The carbon with the least amount of Hydrogens attached to it, will get the hydrogen from HBr, and the other carbon will get the Br
*Amines are derivatives of the ammonia molecule where one or more of the hydrogen atoms have been replaced with an NH2 group
*Amines have an -amine as a suffix, or an amino- as a prefix
*Fishy smell (due to the ammonia)
*Polar molecule- dissolves in water
Substitution: Haloalkane + NH3(alc) ==> Amine
Carboxylic acid + Amine ==> Amide
Amines + Haloalkane ==> Secondary amine
*Amines are basic as they form ammonium ions when added to water
*Solutions can be tested with Red litmus paper- red paper will turn blue
*Named by using -ol as a suffix or hydroxy- as a prefix
*Soluble in water due to the being polar (the O in OH is more electronegative)
*Solubility decrease with chain length as the electronegative effect (pull on electrons) decreases with length
*Higher melting and boiling points than alkanes and alkenes due to stronger electrostatic attraction between molecules
Oxidation: Primary Alcohol + Dichromate/Permanganate => Aldehyde
(Aldehyde + Dichromate/Permanganate => Carboxylic acid)
Oxidation: Secondary Alcohol + Dichromate/Permanganate => Ketone
Reduction: Carboxylic acid + NaBH4 => Aldehyde => Alcohol
Substitution: Alcohol + Hydrogen halide => Haloalkane
Substitution: Alcohol + NH3 => Amine
Elimination: Alcohol + Sulfuric acid => Alkene
Addition: Alcohol + Carboxylic acid => Esters
In the reaction:
Propan-ene + HBr, we have two possible products that can form:
One product will be in more abundance than the other. This is called the MAJOR product and the other one is called the MINOR product.
In order to know which one is which, we follow MARKOVIKOV'S RULE: The rich gets richer.
MAJOR PRODUCT:
The carbon with the most Hydrogens attached to it, will get the hydrogen from the HBr, and the other carbon will get the Br.
MINOR PRODUCT:
The carbon with the least amount of Hydrogens attached to it, will get the hydrogen from HBr, and the other carbon will get the Br
Opposite of Markovnikov's rule:
The poor gets poorer
If atoms in an asymmetrical molecule get removed from a molecule to form an alkene, atoms can be removed from either side of the double bond and will therefore result in two possible products forming.
The majority of the product that forms will follow Saytzeff's rule- the carbon with the least amount of Hydrogens attached to it, will lose another hydrogen.
Reflux
Primary Alcohols get oxidised to become aldehydes. These aldehyde vapours that form, can either be collected as aldehydes, or forced to oxidise further to become carboxylic acids.
Distillation and reflux are used for these two different purposes. Reflux will force aldehydes to continue oxidation, and distillation will collect the aldehyde vapour without them getting further oxidised
Distillation
Alcohols are colourless, odourless, neutral liquids so they can't be identified on physical properties.
Alcohols can easily undergo oxidation to form carboxylic acid, so colour changes can be used to identify alcohols.
Orange Potassium dichromate will turn green when alcohols get oxidised
Purple Potassium permanganate will turn colourless when alcohols get oxidise
Lucas Reagent is a solution that will readily change from colourless to cloudy white in a tertiary alcohol, slower in a secondary and almost never in a primary alcohol. This can be used to determine whether an alcohol is primary, secondary or tertiary.
*Named with -oic acid as suffix
*Polar molecules = Soluble in water
*Higher melting and boiling points than alkanes and alkenes due to the stronger electrostatic attraction between molecules
*Starting material in the formation of amides, acid chlorides and esters
Reduction:
Carboxylic acid + NaBH4 => Primary Alcohol
Neutralisation:
Carboxylic acid + Base => Salt + Water
Carboxylic acid + Amine => Amide
Carboxylic acid + Alchol => Ester
Carboxylic acid + SOCl2 => Acid chloride
Reflux
Primary Alcohols get oxidised to become aldehydes. These aldehyde vapours that form, can either be collected as aldehydes, or forced to oxidise further to become carboxylic acids.
Distillation and reflux are used for these two different purposes. Reflux will force aldehydes to continue oxidation, and distillation will collect the aldehyde vapour without them getting further oxidised
Distillation
Carboxylic acids are acidic as they release hydrogen atoms in solution.
*To test for them, blue litmus paper can be used. The blue paper will turn red in a carboxylic acid
*Carboxylic acids undergo neutralisation reactions with carbonates, producing a salt, water and carbon dioxide. Therefore, carbonates can identify carboxylic acids by producing bubbles/fizzing
*Amides are named by using -amide as suffix
*Amides are derived from carboxylic acids
*Amides are not Basic, like amines
*Higher melting and boiling points due to strong dipole bonding and hydrogen bonding of the N with other molecules
*Soluble in water due to being polar
There is no test for amides as they are:
- not acidic or basic
- soluble in water
- does not oxide/reduce
Therefore, amides are usually the last option and can only be identified after eliminating all other samples.
Acid chloride + Ammonia => Primary Amide
Acid chloride + Amine => Secondary Amide
Ester + Ammonia/alc => Amide
Hydrolysis reactions:
Amide + H20/H => Carboxylic acid + Ammonium
Amide + NaOH => Sodium salt + Ammonia
*Acid chlorides are named by using
-noyl chloride as suffix
*Very reactive and will react vigorously with water so don't dissolve in water
*Release HCl gas when reacted with water
*Moderately low melting and boiling points
Substitution:
Acyl chloride + Water => Carboxylic acid + HCl
Acyl chloride + Ammonia => Amide
Acyl chloride + Alcohol => Ester
Acyl chloride + Primary amines => Secondary amide
As acyl chlorides aren't acidic or basic when in solution, they can't be tested directly with litmus paper.
But, when they mix with water, they produce HCl gas (which is acidic)
Therefore, the vapour of acyl chlorides can be tested with moist blue litmus paper, that will turn red.
From alcohol
From carboxylic acid
*Made by combining a carboxylic acid and alcohol
*Naming: -----yl ----oate
*Esters have a pleasant, fruity smell
*Esters are polar due to the ester link but isn't very soluble in water
*Lower melting and boiling points than carboxylic acids and alcohols as they don't form hydrogen bonds with other molecules
Esterification (formation of an ester):
Carboxylic acid + Alcohol => Ester
Acid chloride + Alcohol => Ester
Hydrolysis (Reverse fo esterification):
Ester + H2O/H => Alcohol + Carboxylic acid
Ester + NaOH => Alcohol + Sodium salt
Ester + Ammonia(alc) => Alcohol + Amide
Ester + Amine => Secondary amide
SAPONIFICATION (Making soap)
*Animal fatty acids are natural esters made from a carboxylic acid and a tri-alcohol (glycerol or 1,2,3-triol)
*When these natural esters are hydrolysed (broken down) with a strong base like NaOH, it breaks apart to form alcohol and a sodium salt.
*This salt is used as SOAP, hence the word Saponification (making soap)
Polymers are formed by adding moleculest together to form a long chain.
Two types of polymerisation:
Addition polymerisation: Adding unsaturated molecules to link into a long chain
Condensation polymerisation: Adding small molecules to form a long chain. A small molecule like HCl or H2O forms as a by-product
*Forming long chains by adding small molecules together.
*These small molecules are unsaturated (alkenes) that bond together because they have an available bond to use.
*These small subunits are called monomers and they form polymers that are named after the monomer
Eg. Polyethene is made from ethene molucules
*Formation of a polymer by adding small molecules together to form a long chain. A small molecule like HCl and H2O is released as by-product.
*There are three types of polymers that form this way:
- Polyesters
- Polyamides
- Proteins
Acid + polyester forms dicarboxylic acid and diols
Base + polyester forms sodium salt and diols
* Formed by molecules with reactive alcohol and carboxylic ends, (hydroxy carboxylic acid) or molecules that have either two carboxylic acid or acid chloride ends with a diol.
*The links between the molecules are called ESTER BONDS
*Polyesters break down (hydrolise) easily with acids or bases. It breaks the ester bonds to return the molecules to their original form.
*The term NYLON is used for a series of polyamides
*Made from a diamine and a dicarboxylic acid or diacyl chloride
*Molecules are bonded together with Amide bonds
*Strong acids hydrolyse (break down) polyamides, releasing a diacid and diamine salt
*Strong bases hydrolyse (break down) polyamides to form a carboxylic acid and a positive NH3 group
*Naturally occurring polymers
*Made from amino acids that contain one alcohol end, and a carboxylic acid end
*The bonds between amino acids are called peptide bonds and many amino acids linked together is called a polypeptide
*Hydrolysis in strong acids form their original amino acids
*Hydrolysis in strong bases form deprotonated carboxylic acid ends