Updated Organic Chemistry IB HL

• Positive ions that are electron deficient and are thus attracted to electron rich molecules.
• NO2+ H+ Nr+
• Lewis acids

• Negatively charged electron rich ions that are thus attracted to electron deficient molecules
• NH3 OH- CL-
• Lewis bases

• Two reactants combine to form a single product.
• Characteristic of unsaturated compounds

• One atom or a group of atoms is replaced by another atom or a group of atoms.
• Characteristic of saturated or aromatic compounds

• Occurs when two reactants join together and as a result, a small molecule such as H2O, HCl or NH3 is lost.
• This reaction occurs between the functional groups of each compound.

Two radicals form from when a covalent bond is broken and the electrons are shared between the two compounds.

Two oppositely charged ions from when a covalent bond is broken and only one product gets all of the electrons.

Compounds with the same molecular formula but different structure,

• Primary: attached to 0 or one other C
• Secondary: attached to 2 other C
• Tertiary: attached to 3 other C
• For amines, it’s a special case. NH2 is primary, NH is secondary and N is tertiary.

• Arenes are a special group of compounds derived from benzene C6H6.
• This special group is called aromatics (different from aliphatics)
• Arenes contain the phenyl functional group.

• Does not act like an unsaturated molecule:
• The molecular formula C6H6 indicates high levels of unsaturation and thus high levels of reactivity. However, benzene is reluctant to undergo addition reactions (as they would disturb the delocalized electron ring and make the compound less stable) and has less isomers than theoretically predicted. Benzene is likely to go through substitution reactions, as this does not disturb the delocalized electron ring.
• Is very stable:
• Delocalized electrons align themselves above and below the hexagonal plane (symmetrically). Due to this, the molecule is highly stable and hydrogenation energy of benzene is lower than the theoretical value.
• Bond lengths:
• All bonds are equal length and and intermediate length between alkanes and alkenes

It is the amount of energy that would need to be supplied in order to overcome the stability of benzene provided by delocalized electrons.

Boiling point also increases as the temporary instantaneous dipol-dipol forces are strengthened.

The boiling point decreases (think of stacking up logs with more branches)

The solubility decreases as the molecule becomes increasingly polar (1-hexanol isn’t soluble for example)

It contains both polar and non-polar groups and can thus dissolve both polar and non-polar substances.

• Alkanes are saturated, non-polar compounds, which explains their low reactivity.
• However, they go through two kinds of reactions:
• Combustion and Halogenation (substitution)

• Alkanes are widely used as fuels, as they release high amounts of energy when they go through combustion.
• Complete combustion produces: CO2 and H2o
• Incomplete combustion produces: CO, C and H2O

• As alkanes are saturated molecules, the main sort of reaction they go through is substitution.
• This occurs when another reactant, such as a halogen, takes the place of a H.
• Methane reacts with Chlorine producing chloromethane and hydrogen chloride in the presence of UV lights.

• Initiation
• Homolytic fission of Cl2 occurs, producing two free radicals of Cl*
• 2) Propagation
• Propagation reactions both use and produce free radicals
• Cl* + CH4 = CH3* + HCl
• CH3* + Cl2 = Cl* + CH3Cl
• CH3Cl + Cl* = CH2Cl* + HCl
• CH2Cl* + Cl2 = CH2Cl2 + Cl*
• 3) Termination
• Termination reactions remove free radicals from the mixture.
• Cl* + Cl* = Cl2
• CH3* + Cl* = CH3Cl
• CH3* + CH3* = C2H6
• Note: The mixture may contain mono or disubstituted alkanes, HCl or larger alkanes

• Bromine water is decolorized in the presence of an alkene without a UV light. This reaction is used to distinguish between alkanes and alkenes.
• Alkenes burn with dirtier and more smoke than alkanes.

• Due to the presence of the easily breakable pi bond, alkenes are more reactive than alkanes and are able to form a variety of saturated products through addition reactions.
• Addition reactions require heterolytic fission.

• Hydrogenation:
• In the presence of Nickel at 150 degrees, alkenes are able to turn into alkanes through hydrogenation
• Addition of Halogens:
• Produces dihalogeno compounds at room temperature. (color change occurs)
• Each halogen attaches to one of the Carbons forming the double bond
• Electrophilic Addition of Halogen halides (HCl or HBr):
• Produces halogenalkanes (one H attaches to one of the Carbons and the other halogen to the other carbon forming the double bond)
• Reactivity increases from Cl to I, as the halogen forms less strong covalent bonds and is more likely to break. Reaction occurs rapidly at room temperature.
• Intermediate called cation is formed.
• Addition of Water (Hydration):
• This produces alcohols in the presence of concentrated H2SO4 as a catalyst.
• H+ and HSO4 are added across the double bond and then replaced by H and OH from the water.
• Polymerization:
• Alkenes easily undergo polymerization by breaking the double bond and turning it into single bonds. (polyethene)

• In the presence of nickel and H2 at 150 degrees, alkenes are able to turn into alkanes through hydrogenation.
• Used to make margarine

• Produces halogenalkanes (one H attaches to one of the Carbons and the other halogen to the other carbon forming the double bond)
• Reactivity increases from Cl to I, as the halogen forms less strong covalent bonds and is more likely to break. Reaction occurs rapidly at room temperature.
• Intermediate called cation is formed as a result of heterolytic fission. Then, the electrophile halogen attaches itself.

In order to have the most stable carbocation intermediate during electrohilic addition of halogen halides to alkenes, the Hydrogen bonded to the most carbons will take place. The halogen will bond to the carbon bonded to the most other carbon atoms.

• In the presence of concentrated H2SO4 as a catalyst, alcohol is produced.
• This is how industrial ethanol is produced.

• The smaller the molecule, the higher the solubility in water.
• Alcohols go through combustion, oxidation and esterification.

Alcohols go through combustion to produce large amounts of energy. The combustion may be complete (producing CO2 and H2O) or incomplete (CO, C, H2O).

• When alcohols go through combustion, the complete oxidation of the molecule occurs. However, it is possible for alcohols to go through selective oxidation of the carbon atom containing the OH functional group in the presence of certain oxidizing agents. Through this, alcohols are able to be oxidized into other organic compounds.
• Various oxidizing agents can be used, however acidified potassium dichromate(VI) is the most common. This is a bright orange solution due to the presence of Cr(VI) which is turned into green Cr(III)
• Primary alcohols: Turn into aldehydes and then carboxylic acids when oxidized in the presence of an oxidizing agent and heat.
• It is possible to obtain the aldehyde through distillation (aldehydes have lower boiling points than alcohols or carboxylic acids as they don’t have hydrogen bonding)
• Add H2SO4 to increase rate of reaction.
• Secondary alcohols: Are oxidized into ketones in the presence of oxidizing agent, heat and reflux)
• Tertiary alcohols: Don’t undergo oxidation, no color change from orange to green.

• Various oxidizing agents can be used, however acidified potassium dichromate(VI) is the most common. This is a bright orange solution due to the presence of Cr(VI) which is turned into green Cr(III)
• Primary alcohols: Turn into aldehydes and then carboxylic acids when oxidized in the presence of an oxidizing agent and heat.
• It is possible to obtain the aldehyde through distillation (aldehydes have lower boiling points than alcohols or carboxylic acids as they don’t have hydrogen bonding)
• Add H2SO4 to increase rate of reaction.

• Secondary alcohols: Are oxidized into ketones in the presence of oxidizing agent, heat and reflux)
• Acidified potassium dichromate is used.

• Tertiary alcohols: Don’t undergo oxidation, no color change from orange to green.
• Potassium dichromate is used.

Collects and contains volatile compounds, allowing them to take part in the reaction for prolonged periods of time. This is important when oxidizing aldehydes into carboxylic acids, alcohols into ketones.

• Alcohol + carboxylic acid in the presence of conc. H2SO4 leads to the formation of H2O and an ester.
• This is an equilibrium reaction and esters can be collected through distillation.
• This is also a condensation reaction, as H2O is released.
• The H from the OH of the alcohol and the OH from the carboxylic acid are removed to form H2O.

• Halogenalkanes are saturated compounds and thus go through substitution.
• They are more reactive than alkanes due to the presence of polar bonds.
• Halogenalkanes go through nucleophilic substitution.
• If the reaction is with OH, alcohol is formed.
• If it’s with CN, a nitrile is formed (particularly useful for increasing the number of C in the carbon chain)
• If it’s with ammonia the product is an amine.

• The halogens are partially negatively charged due to the difference between electronegativities. The carbon gains a partial positive charge and is called electron deficient.
• Heterolytic fission between the halogen and the carbon atom occurs. The halogen acts as the leaving group.
• Thus, halogenalkanes react with nucleophiles such as OH- to form alcohols.
• Primary halogenalkanes: SN2 have a transition state containing both the OH and the halogen. Thus, the rate of the reaction is determined by the concentration of both the OH and the halogenalkane. These reactions are bimolecular.
• Tertiary halogenalkanes: SN1 heterolytic fission occurs and an intermediate compund with neither OH nor Cl is formed. The reaction rate is only determined by the concentration of the halogenalkane. These reactions are monomolecular.

Primary halogenalkanes nucleophilic substitution: Warm dilute NaOH is used. SN2 have a transition state containing both the OH and the halogen. Thus, the rate of the reaction is determined by the concentration of both the OH and the halogenalkane. These reactions are bimolecular. Non-polar solutions prefer SN2.

• Tertiary halogenalkanes nucleophilic substitution: SN1 heterolytic fission occurs and an intermediate compund with neither OH nor Cl is formed. The reaction rate is only determined by the concentration of the halogenalkane. These reactions are monomolecular.
• Carbocations are the intermidates. Polar solutions prefer SN1.

Was a combination of SN1 and SN2

Substitution reactions occur, as they maintain the arene ring.

• In the presence of concentrated H2SO4 50 degrees and HNO3, NO2 replaces a H in the benzene to from H2O and a nitrobenzene. The electrophile is NO2+. In the transition state, both NO2 and H are bonded to the benzene.
• In the presence of AlCl3 in dry ether, a halogen replaces one of the H in the benzene to form halogen halide and HCl.

• SN1 is much faster than SN2
• As the halogen gets less electronegative, the rate of the reaction increases.
• SN1 reactions prefer polar, protic solutions (contains OH or NH and are able to form H bonds) as they stabilize the intermediate.

Aldehydes are reduced to primary alcohols in the presence of LiAlH4 as a source of concentrated H ions.

Reduced to secondary alcohols in the presence of LiAlH4 as a source of concentrated H ions.

• Nitrobenzene is refluxed in the presence of tin and concentrated HCl. The NO2 is replaced with NH3.
• The addition of NaOH releases the free amine and turns it into NH2.

• High priorities on the same side is zusammen
• High properties on opposite sides (like z) are entgegen

Chiral carbon atom within a molecule can either have clockwise or anti-clockwise form. These isomers are called enantiomers and are mirror images of each other. Both are optically active with plane-polarized light. Normally, each enantiomer rotates the plane of the polarized light either left or right in an equal force. A polarimeter is used to detect optical isomers and their presence in a mixture. If the mixture is equal, both enantiomers rotates the plane equally and the substance is called optically inactive (racemic)