IB SL Chemistry Unit 10

UNIT TEN ● Organic Chemistry ○ Organic chemistry is based off of Hydrocarbons ● Naming compounds ○ First find the longest carbon chain- find the prefix associated with that chain ○ Order the carbons in a way that will allow you to have the constituent branch on the lowest carbon ■ Constituent groups are labeled in alphabetical order. That means if you have a methyl and ethyl group, the ethyl comes first. ● Find the functional groups ○ When naming nitrogen containing compounds, you must identify whether the nitrogen is a primary, secondary, or tertiary nitrogen. ○ That is defined by how many constituents are bonded to the nitrogen. ○ If you have an NH2 group, that is a primary amine ○ If you have a N-HCH3 group, you have one methyl group bonded to the nitrogen, making it a secondary amine. ○ If you have an N(CH3)2 group, you have two constituents bonded to the nitrogen, making it a tertiary amine. ● Homologous series ○ Homologous series are chains of organic molecules that vary by a factor of CH2. They also share many similar physical and chemical properties. ● Formulae and structurae ● Properties ○ Boiling point increases with mass ○ Straight chained isomers are stronger than branched isomers ○ functional groups affect boiling point and volatility, that data will be provided in the data booklet. ○ The more polar a compound is, the more soluble. ● Benzene ○ Special example ■ Benzene ring is pictured with 3 double bonds. Benzene is a resonance structure that has bonds that are between a single and double bond. These electrons are delocalised. They aren’t stuck in one bond. Imagine it as a racetrack of electrons, that they can move around the atom.This makes benzene a much more stable molecule than others. ■ All arenes and aromatics are like this ● Reactions of Alkanes ○ Alkanes can go through complete or incomplete combustion. ○ Alkanes can also go through free radical substitution that makes haloalkanes. ■ Free radicals substitution has three steps. ● Step 1- initiation ● Step 2- propagation ● Step 3- termination ■ When doing these reactions you have to write out two propagation states. ○ Example of free radical substitution ● Alkene reactions ○ All alkene reactions occur through the breaking down of the double bond. ○ Alkenes can go through combustion, hydration, hydrogenation, polymerization, substitution reactions, and halogenation reactions. ○ Halogenation- adding a halogen to alkene- produces dihaloalkane ○ Hydration - adding water to alkene- produces alcohol ○ Hydrogenation- adding hydrogen to alkene- produces alkanes ○ Combustion- produces CO2 and Water ○ Polymerization- makes polymers of alkenes. This is important to IB. ■ Polymers can be used in plastics, metals, everyday materials. Nylon is a polymer that we use. ○ Bromine water test- important to IB ■ If you have a substance and are not sure if it is an alkene, react it with bromine water. An Alkene will react with the bromine water, leaving the solution Colorless. You can not say clear. If it doesn't react with the bromine water, then it isn’t an alkene. ■ BENZENE WILL NOT REACT WITH THE BROMINE WATER. ● Its bonds are too strong to be broken. ● Alcohol reactions. ○ Alcohols can go through combustion reactions. ○ They can be oxidized. ■ Oxidizing a primary alcohol will give you an aldehyde. Fully oxidizing a primary alcohol will give you a carboxylic acid. ■ You can reduce an aldehyde into a primary alcohol. ■ Secondary alcohols can be oxidized into Ketones. ■ Ketones can be reduced into a secondary alcohol. ■ Tertiary alcohols can not be oxidized. They are sterically too big to be oxidized. ○ Alcohols react with carboxylic acids to make esters. ■ Esters are known for their distinct fruity smells. ■ This reaction is known as condensation, where the two molecules combine and a water molecule is lost. ● Haloalkanes ○ Can go through nucleophilic substitution reactions. ■ They go through backside attacks. Nucleophile joins onto the end, and the halogen becomes the leaving group. This reaction forms a transition state that is not proven to exist. ● Benzene ○ Goes through electrophilic substitution reactions. ○ Can become nitrated into nitrobenzene. ○ Nitrobenzene can become phenylalanine. ○ You must know that reaction for IB. You will be asked to show all parts of that reduction mechanism.