3 HydrocarbonsA hydrocarbon is a compound containing only hydrogen and carbonCrude Oil, which is very important to the survival Venezuela is a mixture of many hydrocarbonsNot only vital for fuels but also the starting materials for plastics and other polymers
4 AlkanesThe most common hydrocarbon found in crude oil is an alkaneAn alkane contains a ‘backbone’ of single-bonded carbon atoms and is saturated with hydrogen atomsNatural gas, methane, CH4, is the shortest alkaneAlkaneMethane, CH4Ethane, C2H6Propane, C3H8Butane, C4H10Pentane, C5H12Hexane, C6H14Heptane, ______Octane, _______
5 13.2 – Fossil Fuels Most common fuels are fossil fuels Coal, crude oil, natural gas, etcCoal, although it’s not a hydrocarbon, does contain carbon and hydrogen, as well as oxygen in some of it’s moleculesFrom organic material (like trees) that died and were buried below swampsCrude oil, hydrocarbonsFormed from tiny animals and plants which lived in the seaTakes millions of years to form fossil fuelsIn reality the energy comes from the sun to produce fossil fuels, but it simply takes so long to produce
6 13.2 – Finding OilCrude oil today was made from mainly plankton that died about 150 million years ago. Their bodies did not decay normally due to lack of oxygen and with high pressures and temperatures, formed oil and natural gas.We can find oil by surveying the land and it’s topographyLook for dome shaped layers (cap rock or anti-cline)Seismic survey
7 13.3 – Distilling Crude OilWhen crude oil reaches the refinery it’s a thick, black, and smelly liquidThis liquid contains long hydrocarbon chainsAt the refinery the long chains can be sorted out into groups of useful substances called fractionsWe can separate these substances by fractional distillation which separates substances based on their boiling pointFractionLengthColorThicknessReactivityLow BP (up to 80C)ShortClearRunnyEasily lit (flammable, clean flame)Medium BP (80-150C)MediumYellowThickerHarder to light, some smokeHigh BP (above 150C)LongDark orangeThickDifficult to light, smoky flame
8 13.4 – Fractional Distillation in Industry Length of Carbon ChainPetroleum gasC1-C4PetrolC4-C12KerosineC11-C15DieselC15-C19Lubricating OilC20-C30Fuel OilC30-C40BitumenC50 +
9 CrackingAfter distillation of crude oil companies are still left with long hydrocarbons and the need is for shorter chains like petrolThe solution is cracking meaning big molecules are broken down by heating them over a catalystThis is competed inside a cracker
10 PlasticsWhen oil companies crack large molecules into smaller ones, ethene is madeEthene is just like ethane, but with a double bond making it unsaturatedThis ethene molecule is the starting material for plastics. When the double bond is broken, new bonds can form between several molecules forming polymersLots of small, reactive molecules called monomers join together to make a polymervsethene
11 13.7 – Ethene and the Alkenes Alkenes, which are also hydrocarbons, are very similar to alkanes, but are not saturated. They have at least one double bond and less hydrogen atoms which makes them unsaturated.Their names end in –ene instead of –aneContain double bondsVery reactiveBuilding block for polymersAlso react withBr, Cl, I, F waterStrong acidsWater and sulfuric adidAlkaneAlkeneMethane, CH4Ethane, C2H6Ethene, C2H4Propane, C3H8Propene, C3H6Butane, C4H10Butene, C4H8Pentane, C5H12Pentene, C5H10Hexane, C6H14Hexene, C6H12Heptane, ______Heptene, ______Octane, _______Octene, _______
12 PolymerizationThere are two types of reactions that make polymersAddition – where at least two things simply join togetherCondensation – where water is given off in the process of joining molecules. Also known as dehydration synthesis
13 13.8 – Addition Polymerization Addition ReactionsMonomers have at least one double bondThe polymer is the only material formed in the reactionEasiest example is ethene used to make poly(ethene)n C2H4 -[-C2H4-]-nWhere n = large numberThe double bonds open up to form single bonds to the adjacent monomerR can be just about anything
14 13.9 – Condensation Polymerization Nylon is an example of a polymer formed through condensationFumes are given off as the different monomers react together. These small molecules given off could be H2O, HCl, etc. It depends on the ends of the monomers.The monomers have reactive parts at both ends and join end-to-end to make long chain polymers+ H2O
15 13.10 – Properties of Plastics Many materials are made out of plasticsPVC piping, bags, surfaces, protective films, bottles, etcPlastics often have advantages over the use of metal compounds and cost much lessWhen we run out of oil we will also run out of access to cheap plasticsThis is why recycling our plastics is so important!!
16 Chapter 14 – Organic Molecules Nomenclature!How do we name organic compounds?Alkane vs alkeneSaturated vs unsaturatedFunctional groupsLength of chain
17 Types of Organic Molecules 14.1 – Types of OrganicsTypes of Organic MoleculesSaturatedUnsaturatedCompounds which contain only single bondsFor example: alkanesCompounds which contain double or triple bondsFor example: alkenes, arenesAliphaticsArenesCompounds which do not contain a benzene ring; may be saturated or unsaturatedFor example: alkanes, alkenesCompounds which contain a benzene ring; they are all unsaturated compoundsFor example: benzene, phenol
18 14.2 - Members of Homologous Series Differ by a CH2Can be represented by the same general formulaShow gradation in physical propertiesHave similar chemical properties
19 14.2 - Members of Homologous Series… … differ by a –CH2 group
20 14.2 - Members of Homologous Series… … can be represented by the same general formula NameCH4OHMethan-1-olC2H5OHEthan-1-olC3H7OHPropan-1-olC4H9OHButan-1-olC5H11OHPentan-1-olC6H13OHHexan-1-olC7H15OHHeptan-1-olC8H17OHOctan-1-ol
21 14.2 - Members of Homologous Series… … show gradation in physical properties AlkaneBoiling PointMethane, CH4-164Ethane, C2H6-89Propane, C3H8-42Butane, C4H10-0.5Pentane, C5H1236Hexane, C6H1469Heptane, C7H1698Octane, C8H18125Since the series differ by one –CH2 they have successively longer carbon chainsResults in gradual trend of phy. PropsNot always a linear growthDensity and viscosity are other examples
22 14.2 - Members of Homologous Series… … show similar chemical properties As the have the same functional groupEx.1 – the alcohols have a functional –OH group, which can be oxidized to form organic acidsEx. 2 – the –COOH functional group, present in the homologous series of the carboxylic acids, is responsible for the acidic properties of these compounds
23 14.3 – Organic Formulas Emperical formula Molecular formula Simplest whole number ratioEthane CH3Molecular formulaActual number of atomsEthane C2H6Structural FormulaFull, condensed, steriochemical
24 Emperical FormulaThe simplest whole number ratio of the atoms it contains. For example, the emperical formula of ethane, C2H6, is CH3. This formula can be derived from percentage composition data obtained from combustion analysis. It is, however, of rather limited use on it’s own, as it does not tell us the actual number of atoms in the molecule.
25 Molecular FormulaActual number of atoms of each element present. For example, the molecular formula of ethane is C2H6. It is therefore a multiple of the emperical formula, and so can be deduced if we know both the emperical formula and the relative molecular mass Mr.
26 14.3 - Full Structural Formula Graphic formula or displayed formula – shows every bonded atom. Usually 90o and 180o angles are used to show the bonds because this is the clearest 2-D representation, although it is not the true geometry of the molecule
27 14.3 - Condensed Structural Formula Often omits bonds where they can be assumed, and groups atoms together. It contains the minimum information needed to describe the molecule non-ambiguously – in other words there is only one possible structure that could be described by its formula.
28 14.4 – IUPAC NomenclatureNomenclature for Organic Compounds: the IUPAC systemInternational Union of Pure and Applied ChemistryRule 1: Identify the longest straight chain of carbonsRule 2: Identify the functional groupRule 3: Identify the side chains or substituent groups
29 14.4 - IUPAC Rule 1: Longest Chain # C atoms in longestStem in IUPAC nameExample1meth-CH4 methane2eth-C2H6 ethane3prop-C3H8 propane4but-C4H10 octane5pent-C5H12 pentane6hex-C6H14 hexaneNote: ‘straight chain’ does not mean just 180o angles or unbranched chains of carbon atoms. Be careful, do not be confused by the way the molecule may appear on paper because of free rotation around the carbon-carbon single bonds. Example, all three below are the same….
30 15.4 - IUPAC Rule 2: Functional Group The functional group is described by a specific ending (or suffix) to the name, that replaces the –ane ending of the name of the parent alkane. The suffixes used for some common functional groups are in the slides to follow. Those marked * will have slides with further information.
31 14.4 - Functional Groups Homologous Series Functional Group Suffix in IUPAC nameExample of compoundAlkane-aneC3H8 propaneAlkene-eneCH3CH=CH2 propeneAlcohol-anolC3H7OH propanolHalogen-Cl -F -Brchloro, Fluoro, bromochloromethane
32 14.4 - IUPAC Rule 3: Side Chains Prefix in IUPACExample of Compound-CH3methly-CH3CH(CH3)CH32-methylpropane-C2H5ethly-CH(C2H5)33-ethlypentane-C3H7proply-CH(C3H7)34-propylheptane-F , -Cl , -Br , -Ifluoro- , chloro- , bromo- , iodo-CCl4Tetrachloromethane-NH2amino-CH2(NH2)COOH2-aminoethanoic acid
33 Structural IsomersDifferent arrangements of the same atoms make different moleculesMolecular formula shows the atoms that are present in a molecule, but gives no information on how they are arranged. Consider, for example, C4H10Each isomer is a distinct compound, having unique physical and chemical properties.
35 Alkanes as FuelsRelease significant amounts of energy when they burn, highly exothermic, because large amount of energy released when forming..Double bonds of CO2Bonds in H2OC3H8 + 5O2 3CO2 + 4H2O ΔH = kJ/molHowever, when O2 is limited…..2C3H8 + 7O2 6CO + 8H2Owhen O2 is extremely limited…..C3H8 + 2O2 3C + 4H2OThese are examples of the incomplete combustion of fossilfuels which makes them an environmental concern