organics

Organic chemistry NCEA

Alkene to Alkane

H₂ with Ni, Pd or Pt Catalyst

Alkene to Haloalkane

Hydrogen Halide (HX)

Alkane to Haloalkane

Halogen (X₂) and UV Light

Haloalkane to Alkene

KOH (alc)

Alkene to Alcohol

H₂O/H⁺ or dil. H₂SO₄

Alkene to Diol

MnO₄⁻/H⁺

Haloalkane to Alcohol

KOH (aq)

Alcohol to Haloalkane

Hydrogen Halide (HX)

Alcohol to Chloroalkane

SOCl₂ or PCl₃ or PCl₅

Alcohol to Carboxylic Acid

MnO₄⁻/H⁺ or Cr₂O₇/H⁺

Alcohol to Alkene

conc. H₂SO₄

Haloalkane to Amine

conc. NH₃ or NH₃ (alc)

Carboxylic Acid to Metal Carboxylate Salt

Metal or Base

Carboxylic Acid to Alkylammonium Salt

Amine

Amine to Alkylammonium Salt

Carboxylic Acid

Alkene to Alkane

Addition

Alkene to Haloalkane

Addition

Alkane to Haloalkane

Substitution

Haloalkane to Alkene

Elimination

Alkene to Alcohol

Addition

Alkene to Diol

Oxidation

Haloalkane to Alcohol

Substitution

Alcohol to Haloalkane

Substitution

Alcohol to Chloroalkane

Substitution

Alcohol to Carboxylic Acid

Oxidation

Alcohol to Alkene

Elimination

Haloalkane to Amine

Substitution

Carboxylic Acid to Carboxylate Ion

Acid-Base

Carboxylic Acid to Alkylammonium Salt

Acid-Base

Amine to Alkylammonium salt

Acid-Base

alkene to dihaloalkane

Halogen (X₂)

alkene to dihaloalkane

addition

alkene to polymer

alkene + catalyst

alkene to polymer

addition polymerisation

Melting and Boiling Points of Alkanes

increases as carbon chain increases.

•Alkanes molecules are held together by weak intermolecular forces

•As the molecules get larger the strength of these forces gets stronger

•Melting and Boiling requires breaking the intermolecular bonds

•So as the carbon chain get longer the strength of the bond gets greater so more energy is required to break them and change state so the melting and boiling points get higher

Solubility of Alkanes

•All alkanes are insoluble in water and will form two layers when added together

electronegativity difference is too small for a significant dipole to be formed

•This is because water is polar, and alkanes are non-polar (more on this in 2.4)

•As a rule, polar substance can dissolve in other polar substances and vice versa for non-polar

state of alkane at room temperature

•1 – 4 carbon chain are gases

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•5 – 17 carbon chain are liquids

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•18+ carbon chain are solids

Saturated and unsaturated molecules

•A molecules is considered saturated if every carbon atoms has the maximum number of hydrogen atoms attached that it can.

eg. carbon bonds on double bonds are unsaturated as an extra hydrogen would be ableto be there if it weren’t

Geometric isomers

•Geometric Isomers are molecules that have the same structural formula but different 3D spatial arrangements

geometric isomer requirement

double bond to prevent rotation (bond is rigid, so it does not allow rotation to occur around it) – Single bonds allow free rotation, so they don’t have geometric isomers.
2.There must be different groups on each of the carbon in the double bond

Testing for the presence of a double bond

add Br:•

When the brown Br₂ was added to the alkene it very quicky discolored as it was reacted to form a dibromoalkane. This was an addition reaction

•When the brown Br₂ was added to the alkane it reacted very slowly and needed uV light to form a bromoalkene. This was a substitution reaction

(addition occurs faster as the bonds are weaker)

Markovnikovs rule

•When an asymmetrical reagent (eg. HCl) is added to an asymmetrical alkene two products are formed

•The carbon atom in the double bond with the most hydrogens already attached will get another hydrogen and the carbon atom with the least hydrogen atoms will get the other atom(s)

polymerisation

•Polymerisation is the process of linking many smaller molecules together to make a long chain.

properties of polymers

•Due to the incredibly long carbon chain polymers are solids at room temperature

•Due to the lack of a double bond, polymers are generally unreactive.

reactivity of monomers and polymers

•Key Idea: Double bonds are strained and therefore more reactive, single bonds are not strained and therefore less reactive.•

•This means monomers, because they have a double bond are reactive but polymers, because they don’t, aren’t

addition polymerisation process

1.Addition polymerization is the process of taking multiple alkenes (monomers) and adding them together to form a long chain (polymer)

2.During addition polymerization, the double bond on a monomer is broken open leaving only a single C – C bond.

3.This allows for 2 new C – C bonds to form between monomers allowing for a long chain to form.

4.Polymerisation only occurs when a catalyst (and often heat) is added

Melting and Boiling Points of Alcohols

As the carbon chain gets longer there is more / stronger intermolecular forces so the melting points and boiling points go up (same as alkanes)

Solubility in Water

•Follows the opposite trend to melting points and boiling points – As the carbon chain gets longer the solubility decreases

•The –OH group is polar whereas the carbon chain is non-polar

•Remember that water is polar, the longer the carbon chain the more non-polar the molecules is so the less it will be soluble

•Methanol, Ethanol and Propanol are all infinitely soluble

compounds are miscible in water meaning

mixes completely

Elimination Reactions

Elimination reactions are reaction that form a double bond by eliminating two groups

Zaytsev's rule

•It states “The carbon either side of the –OH group with the fewest hydrogens will get fewer hydrogens”

this rule is applied to 2nd degree alcohols

H2SO4

Concentrated sulfuric acid is such a strong dehydrating agent that it will remove a hydrogen atom and the hydroxyl group from an alcohol and combine them to form a water molecule (byproduct). The hydrogen atom and hydroxyl group are taken from adjacent carbon atoms, and those carbon atoms are then joined with a double bond creating an alkene