Organic Chemistry A Brief Introduction

1. Organic ChemistryA Brief Introduction Text reference: Ch 20

2. What is organic chemistry? • What isn’t it? • Organically grown fruits & veggies • It IS a branch of chemistry that deals with molecules containing the element carbon, bound to other elements. • Many (most) of these molecules are produced by living things (organisms organic) • So why do we call them “organically grown”?

3. Organic molecules • What carbon-containing molecules can you think of (maybe from biology???) • Glucose C6H12O6 organic • Sucrose, dextrose and all the other “oses” • Sugars are organic • CO2 – carbon dioxide – inorganic • CO – carbon monoxide – inorganic • Most other carbon-containing molecules are organic • Many can be duplicated in laboratory

4. Uses of Organic Compounds • Any ideas? • See p. 699 • Fuel (from decayed living matter) • Plastics • PVC • Velcro • Artificial sweeteners

5. Carbon Bonding • How many valence electrons does carbon have? • 4 • Carbon bonds readily with many, many, many other elements in a billion different ways. • It’s very versatile. • (BTW: Sulfur does the same thing in the non-living world… but that’s the stuff of earth science)

6. Hydrocarbons • The simplest of organic molecules. • What elements do you suppose hydrocarbons contain? • Hydrogen & carbon • Simplest of simplest = methane • Methane = one carbon atom, surrounded by 4 hydrogens, each sharing valence electrons

7. Methane

8. Methane is Natural Gas

9. Organic molecules are bonded covalently • Lewis dot structures show shared electrons as dashes, instead of two dots.

10. What is the chemical formula for methane? • CH4

11. Each carbon molecule has ____ bonding possibilities • 4 • In hydrocarbons, carbon bonds with itself and hydrogen • If the hydrocarbon is “saturated”, then all four available bonds of carbon are shared, or filled, by other atoms. • Saturated hydrocarbons are called alkanes

12. Naming Saturated Hydrocarbons • When naming, alkanes all end in “ane” • One carbon = methane • Two carbons = ethane

13. Ethane (of the famed ethanol – we’ll get to that) • Ethane is a molecule made up of two carbons, surrounded by hydrogen using all the other available bonding spaces • What is the formula for ethane? • CH3CH3

14. Naming Alkanes

15. Memorize prefixes!!! • (QUIZ TOMORROW ON PREFIXES and formulas) • meth1, starts with m, like mono does • eth 2, follows meth, but isn’t mono, so drop the m • prop- 3, How can you remember this? • But- 4, rhymes with cute, which has four letters

16. Prefixes to Memorize, cont’d The rest of the prefixes are the same as the ones you’ve already learned for covalent naming • penta, 5, as in pentagon • hex – hex has an “x” like six does • hept - seven • oct– octopus has 8 legs • non- – sounds like nine • dec- – a decade has ten years

17. Carbon Chains Have KinksWhat alkane do all these diagrams represent?

18. Carbon Chains Can Take Turns • see board for this

19. Carbon Chains Can Form Rings • To name these, add the prefix “cyclo” in front of the alkane name • ex: hexane becomes cyclohexane

20. Carbon Chains Can Have Other Groups of Atoms Attached to Them • When the attached groups are made up of hydrocarbons, these are called alkyl groups • Carbon groups attached to carbon chains are named by using the prefix for the number of carbons in the group + “yl” • Ex: methyl = CH3 attached to any carbon chainat any point. (see Table 20.2 on p. 709)

21. Naming Alkanes(see Rules for Naming Alkanes on p. 710) • Find longest carbon chain • Number the carbons from the end closest to the first alkyl group • List alkyl groups in alpha order (disregarding prefix), with carbon number they’re attached to preceding group name • If more than one of the same kind of alkyl group exists, use di, tri, etc. prefixes in front of that alkyl group’s name

22. Naming Alkanes • Ex: count the carbons in the longest chain: • Eight carbons = octane • Methyl group on carbon #4 • Ethyl group also on carbon #4 • 4-ethyl, 4-methyl octane

23. Try Some! • HW: • Text p. 713 Practice Problems (answers in green section in back) • Text p. 714 Practice problem • Text p. 717 #8 a-d (watch out for bending carbon chains!)