Organic Chemistry

1. Organic Chemistry

2. Some organic chemicals • Medicines • Active Pharmaceutical Ingredients • Excipients DNA Fuels Materials Essential oils Pigments

3. Organic Chemistry Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate, fish, mint Medications:Aspirin, Tylenol, Decongestants, Sedatives Addictive substances: Caffeine, Nicotine, Alcohol, Narcotics Hormones/Neurotransmitters: Adrenaline, Epinephrine Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins Genetics: DNA, RNA Consumer products: Plastics, Nylon, Rayon, Polyester

4. An organic compoundis one that has carbon as the principal element. • An inorganic elementis any compound that does not contain carbon.

5. Carbon is unique • It has 6 electrons and has 4 valence electrons in its outer shell. • It has room for 4 bonds to 4 other atoms. If there are four atoms or groups around a carbon atom, it has a tetrahedral geometry.

7. Where does most of our carbon containing products come from?

8. What is crude oil? Crude oil is a fossil fuel and one of the most important substances in the world. It is a mixture of hundreds of different compounds. Crude oil is used to make fuels for transport, heating and generating electricity. It is also used to make plastics and hundreds of different types of chemicals. Every day, the world uses over 70 million barrels of oil. If you filled bath tubs with this amount of oil and put them end-to-end, they would stretch round the Earth 7.5 times!

9. How was crude oil made? Crude oil is thought to have been made from the remains of marine plants and animals that died millions of years ago. These remains sank to thebottom of the sea, where theywere buried in layers of sand andmud, preventing them from rotting. These layers gradually became sedimentary rock. Over millions of years the layers of rock built up, increasing the heat and pressure. This caused the remains to be broken down into the molecules that form crude oil and natural gas.

10. Hydrocarbons in crude oil Many compounds in crude oil only contain the elements carbon and hydrogen. They are called hydrocarbons. Most hydrocarbons in crude oil are compounds called alkanes. Alkanes contain a single chain of carbon atoms with hydrogen atoms bonded along the side.

11. Finding crude oil at sea Oil rigs or drilling platforms are used to drill through the sea bed to obtain the oil. Once the oil has been removed from the sea bed, it is pumped in long pipelines to an oil tanker terminal or an oil refinery on land.

12. How can crude oil be made useful? Crude oil itself has no uses – it must first be processed or refined. This is done in an oil refinery. The first step is to separate compounds in the oil into groups called fractions. Each fraction contains a mix of compounds with a similar number of carbon atoms. http://www.youtube.com/watch?v=26AN1LfbUPc

13. 4.Lighter fractions (containing small molecules) have a lower boiling point and condense further up the column. Fractional distillation of crude oil Crude oil is separated into fractions by fractional distillation. 1.Oil is heated to about 450 °C and pumped into the bottom of a tall tower called a fractionating column, where it vaporizes. 2.The column is very hot at the bottom but much cooler at the top. As the vaporized oil rises, it cools and condenses. 3.Heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column.

14. Generally, the larger a hydrocarbon, the higher its boiling point. Molecule size and boiling point Molecules in crude oil can contain anything from just 1 carbon atom to well over 50. The more carbon atoms in a hydrocarbon molecule, the larger the molecule. How does this affect its boiling point? This is because the intermolecular forces between large molecules are stronger than the intermolecular forces between small molecules. More energy is needed to break the forces between large molecules, and so the boiling point is higher.

15. A tall column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with low boiling points condense at the top. Fractional distillation works because the different substances in the mixture have different boiling points.

16. This is the sequence of events in distillation: heating → evaporating → cooling → condensing

17. Supply and demand Crude oil often contains more heavier fractions than lighter fractions, which are more useful and therefore more desirable. The large hydrocarbon moleculesin the heavier fractions can bebroken down into smaller, more useful, molecules to meet demandfor raw materials for fuels and plastics.

18. Catalytic cracking Large hydrocarbon molecules can be broken down into smaller molecules using a catalyst. This is called catalytic cracking. The hydrocarbon molecules are heated until they turn into vapour, and then mixed with a catalyst. The type of reaction in catalytic cracking is called thermal decomposition. The smaller molecules produced by catalytic cracking are a mixture of alkanes and alkenes. Alkenes are reactive molecules that are used to make plastics and other chemicals.

19. When will crude oil run out? It is difficult to say when crude oil will run out because no-one knows exactly how much oil there is left in the world. There are over 1 trillion (1 million million) barrels of crude oil in proven oil reserves At current rates, this will last about 44 years, but the amount of oil used in the world increases each year. Some scientists believe there is a lot more oil still to find, but others think that most oil has already been discovered.

20. Cracking decane Decane from the naphtha fraction can be cracked to form pentane (for use in petrol), propene and ethene. decane (C10H22)  + + pentane (C5H12) propene (C3H6) ethene (C2H4)

21. Problems with crude oil Crude oil is extremely useful but it has several drawbacks: • Burning the products of crude oil as fuel produces gases and particles that contribute to global warming and air pollution. • Removing oil from the ground, as well as oil spillages and slicks, can be very damaging to wildlife and the environment. • The high value of oil means it is sometimes the cause of military conflict, especially because a large amount of oil comes from countries that are politically unstable.

22. Hydrocarbon Classification • A hydrocarbon is a compound consisting of only hydrogen and carbon.

23. Shortcuts make structures easier & faster to draw Butane: C4H10 Lewis Structure Carbon Atoms • Line Structure • Only shows bonds • C atoms assumed at each end and intersection of bonds • H atoms not shown • Assume 4 bonds to each C • Fulfill C’s 4 bonds by adding H’s Condensed Structures CH3CH2CH2CH3 CH3(CH2)2CH3

24. First 10 Alkanes

25. Drawing Organic Structures Shortcuts make structures easier & faster to draw Butane: C4H10 Lewis Structure Carbon Atoms • Line Structure • Only shows bonds • C atoms assumed at each end and intersection of bonds • H atoms not shown • Assume 4 bonds to each C • Fulfill C’s 4 bonds by adding H’s Condensed Structures CH3CH2CH2CH3 CH3(CH2)2CH3