1. The chemistry of compounds containing carbon.

2.  Refinery and tank storage facilities, like this one in Texas, are needed to change the hydrocarbons of crude oil to many different petroleum products. The classes and properties of hydrocarbons form one topic of study in organic chemistry.

3.  A hydrocarbon is a compound consisting of only hydrogen and carbon.  The carbon to carbon can be single, double, or triple bonds.  The bonds are always nonpolar.

4. Here are some Characteristics of hydrocarbons: Has non-polar molecules sp 3 hybridization Contains only hydrogen and carbon non-electrolytes because of poor ionization In "most** situations, it is not soluble in water The reactivity is very slow The low boiling point makes it pretty easy to decompose an organic compound (as acetylene or butane) containing only carbon and hydrogen and often occurring in petroleum, natural gas, coal, and bitumens Presented by Brent Daigle, Ph.D. (ABD)

5.  Carbon-to-carbon bonds can be single (A), double (B), or triple (C). Note that in each example, each carbon atom has four dashes, which represent four bonding pairs of electrons, satisfying the octet rule.

6.  Carbon-to-carbon chains can be (A) straight, (B) branched, or (C) in a closed ring. (Some carbon bonds are drawn longer, but are actually the same length.)

8. 3-8 1.Hydrocarbons - molecules that possess only hydrogen and carbon a1. Alkanes – noncyclic hydrocarbons with only C-C single bonds. Formula C n H 2n+2 where n is an integer. a2. Cycloalkanes – cyclic hydrocarbons with only C-C single bonds. Formula C n H 2n where n is an integer. Example: Butane CH 3 CH 2 CH 2 CH 3 C 4 H 10 Example: Cyclobutane C 4 H 8 b1. Alkenes – noncyclic hydrocarbons with C=C double bonds. Formula C n H 2n where n is an integer. Example: 2-Butene CH 3 CH=CHCH 3 C 4 H 8

9. 3-9 c. Alkynes – noncyclic hydrocarbons with C ≡ C triple bonds. Formula C n H 2n-2 where n is an integer. Example: Butyne CH 3 C ≡ CCH 3 C 4 H 6 b2. Cycloalkenes – cyclic hydrocarbons with C=C double bonds. Formula C n H 2n-2 where n is an integer. Example: Cyclobutene C 4 H 6 d. Aromatic Hydrocarbons – benzene and its derivatives or C 6 H 6

10. 3-10 2. Compounds containing Oxygen a. Alcohols R-OH Functional Group OH hydroxyl group CH 3 OH methyl alcohol HOCH 2 CH 2 OH ethylene glycol (antifreeze) b. Ethers R-O-R CH 3 CH 2 -O-CH 2 CH 3 Diethylether c. Aldehydes and Ketones Functional Group C=O carbonyl group

11. 3-11 d.Carboxylic Acids Functional Group -CO 2 H -COOH -COH Carboxyl Group O Acetic Acid e. Derivatives of Carboxylic Acids Ester Acid Chloride Amide

12. 3-12 3. Nitrogen-Containing Molecules a. Amines R-NH 2 Functional Group -NH 2 amino group Amines are Lewis and Bronsted bases because of the nonbonded pair of electrons.. b. Amides (see above) c. Nitriles Functional Group Cyano Group

13. 3-13 Single versus Double Bonds Ethane The carbon-carbon single bond in ethane freely rotates at room temperature. Ethylene The carbon-carbon double bond in ethylene does not freely rotate at room temperature. Why not? Answer: The Pi bond would have to be broken. It will not break at room temperature Pi bond broken

14. 3-14 Isomers – different compounds with the same formula a.Constitutional (Structural) Isomers – isomers that differ in their bonding sequence C 5 H 12 C 2 H 2 BrCl b. Stereoisomers – isomers that differ in their spatial orientation C 2 H 2 BrCl Cis isomer Trans isomer

15. 3-15 Use of Wedges and Dashed Lines Solid Wedge indicates “coming toward you” Dashed Line indicates “going away” Narrow Line indicates “in the plane of paper” Question: Are the above cycloalkanes constitutional or stereoisomers? Answer: Stereoisomers

16.  Alkanes are hydrocarbons with only single bonds. SATURATED HYDROCARBONS – they contain only C & H they have only C-C and C-H single bonds Contain the maximum possible number of H per C Occasionally referred to as ALIPHATIC compounds; Greek aleiphas, meaning fat (many animal fat contain long carbon chains similar to alkanes)  Alkanes occur in what is called a homologous series.  Each successive compound differs from the one before it only by a CH 2

17. Characteristics AKA Paraffins, are chemical compounds that consist only of the elements carbon (C) and hydrogen (H). Each are linked by a single bond. Each carbon atom must have 4 bonds (either C-H or C-C bonds), and each hydrogen atom must be joined to a carbon atom (H-C bonds). General formula C n H 2n+2 (Linear saturated hydrocarbon) Brent Daigle, Ph.D. (ABD)

18.  PHYSICAL PROPERTIES 1. Non-polar – comparable EN of C & H; symmetrical cmpd. 2. Low b.p. (-161.5 o ), or low m.p.(-83 o ) – weak VW attraction. 3. Colorless 4. Sp. Gravity = 0.4 g/mL 5. Slightly soluble in water the simplest alkane Chemical structure of methane Tetrahedral 109.5 o MW=16 g/ml SOURCES: 1.END PRODUCT OF ANAEROBIC DECAY OF PLANT AND ANIMALS It is a major constituent of natural gas (97%) Fire damp of coal mines Marsh gas bubbling in swamp Methane can be isolated by fractional distillation 2.OXIDATION BY HALOGENS (HALOGENATION)

19. The Alkanes Methane H H C H CH 4 H Propane H H H H C C C H C 3 H 8 H H H Ethane H H H C C H C 2 H 6 H H Presented by Brent Daigle, Ph.D. (ABD)

20. The number of carbon atoms = root name!  meth 1 carbon  eth2 carbon  prop3 carbon  but4 carbon  pent5 carbon  hex6 carbon  hept7 carbon  oct8 carbon  non9 carbon  dec10 carbon Presented by Brent Daigle, Ph.D. (ABD)

21. 3-21 Physical Properties of Alkanes 1. Combustion - Alkanes are flammable, i.e. they burn. 2 2. Boiling and melting points a. Both bp and mp increase with increasing carbon number for straight- chain alkanes with formula C n H 2n+2 Carbon Number Physical State C 1 - C 4 gases C 5 – C 16 liquids C 17 – C 30 oils and greases C 30 – C 50 paraffin waxes >C 50 plastics (polyethylene)

22. 3-22 b. Branching tends to lower the boiling point and raise the melting point BP 60 o C 58 o C 50 o C MP -154 o C -135 o C -98 o C Explanation: MP Branching reduces the flexibility of the molecule which reduces the entropy term  S in the equation T mp =  H/  S. Since  S is in the denominator, T mp increases. BP Branching reduces surface area (more compact structure), and therefore London dispersion forces which control boiling point for these molecules. 3. Solubility – alkanes are nonpolar molecules and therefore insoluble in water, which is polar. Alkanes are hydrophobic. 4. Densities – alkanes are less dense than water, with densities near 0.7 g/mL. Therefore they float on water, e.g. Exxon Valdez oil spill.

23.  Petroleum is a mixture of alkanes, cycloalkanes, and aromatic hydrocarbons.  Petroleum is formed from the slow decomposition of buried marine life, primarily plankton and algae.  As petroleum is formed it is forced through porous rock until it reaches an impervious layer of rock.  Here it forms an accumulation of petroleum and saturated the porous rock creating an oil field.

24.  Crude oil is the petroleum that is pumped directly from the ground.  It is a complex mixture of hydrocarbons with one or two carbon atoms up to a limit of about 50 carbon atoms.  This is usually not useful, so it must separated by distillation.

25.  Crude oil from the ground is separated into usable groups of hydrocarbons at this Louisiana refinery. Each petroleum product has a boiling point range, or "cut," of distilled vapors that collect in condensing towers.

26.  Petroleum products and the ranges of hydrocarbons in each product.

27.  The octane rating scale is a description of how rapidly gasoline burns. It is based on (A) n- heptane, with an assigned octane number of 0, and (B) 2,2,4- trimethylpentane, with an assigned number of 100.

28. 3-28 Octane Number Straight-chain hydrocarbons have low octane and make poor fuels. Octane Number = 0 Branched Alkanes burn more slowly and reduce the knocking in the engine. heptane 2,2,4-trimethylpentane Octane Number = 100

29. 3-29 1. The first step in petroleum refining is fractional distillation 1. The first step in petroleum refining is fractional distillation.

30. Separate fractions based on differences in boiling point.

31. 3-31 Refining of Petroleum

32. 3-32 2. Upstream processing of the distillates. a. Catalytic hydrocracking – produces small alkanes from large alkanes by adding hydrogen. b. Catalytic cracking – produces small alkenes and alkanes by cracking in the absence of hydrogen. c. Catalytic Reforming – the alkanes and cycloalkanes are upgraded to higher octane number by conversion into aromatic compounds.

34.  Removing HYDROGEN from an alkane, the partial structure that remains is called an ALKYL GROUP.  Are NOT stable compounds themselves, they are simply PARTS of larger compounds. –ane –yl  Are named by replacing the –ane ending of the parent alkane with a –yl ending.

36. sec- tert-  In naming alkyl groups: the prefixes sec- (for secondary) and tert- (for tertiary) used for the C 4 alkyl groups, refers to the number of other carbon atoms attached to the branching carbon atom. primary (1 o ), secondary (2 o ), tertiary (3 o ) and quaternary (4 o ).  There are 4 possibilities: primary (1 o ), secondary (2 o ), tertiary (3 o ) and quaternary (4 o ).

38. Sample problems