Presentation on theme: "Organic Chemistry Objectives"— Presentation transcript:
1 Organic Chemistry Objectives Name alkanes from the structure and given the name, be able to draw the structure.Distinguish between saturated and unsaturated hydrocarbons.Describe the structures of alkenes and alkynes.Name alkenes and alkynes from their structure and given the name, be able to draw the structure.Describe the properties of alkanes, alkenes and alkynes.Describe functional groups and give examples.Describe the structures of alkanes, including branched, unbranched, and cyclic alkanes.Describe polymers.
2 Hydrocarbons Hydrocarbons are organic compounds. -organic compound: carbon containing compounds with the exceptions of carbon dioxide, carbides and carbonates-contain hydrogen and carbon-simplest of the organic compounds-covalent moleculesClassified as: alkanes, alkenes, alkynes, aromatics
3 Alkanesalkane: hydrocarbon containing only C-C single bonds (-ane ending)-saturated hydrocarbon: each carbon contains amaximum of 4 single covalent bonds with otheratoms-can be shown as straight chains, branched chains,or cyclic chains-follows the formula:CnH2n+2example: if n = 1, then C1H2(1)+2to give CH4
4 Unbranched AlkanesC-C bonds form in a straight line.
5 Naming Unbranched Alkanes 1. Use a prefix for the number of carbons it contains:meth- 1 C hex- 6 Ceth- 2 C hept- 7 Cprop- 3 C oct- 8 Cbut- 4 C non- 9 Cpent- 5 C dec- 10 C2. Follow the prefix with the ending, -aneExample: C8H18 is named octaneHint: Hydrogen has nothing to do with the actual naming of the compound, except help you determine if the C-C bonds are single or multiple
6 Branched AlkanesName is derived from a straight-chain alkane by replacing one or more of thehydrogen atoms by alkyl groups(which are substitued for one ormore H’s)1. a suffix that identifies the parentstraight-chain alkane♦count the number of C atoms inthe longest continuous chain2. a prefix that identifies thebranching alkyl group and thenumber of the carbon atom to which it is attached(see p 702, Table 22-2)
7 Naming Branched Alkanes 1. Propane will be part of this compound’s name because the longest continuous chain has three carbons.2. Two methyl branches are present, both on the second carbon.♦when more than one branch of the same kind is shown, use the Greek prefixes (mono-, di-, etc.)♦number each substituted group using the number of the carbon it is attached to (in this case, C #2)
8 Naming Branched Alkanes What do we have?- propane as the parent chain- two methyl groups on the secondcarbonThe name is:2,2-dimethylpropaneBranched alkanes can become very complicated very quickly.
9 Naming Branched Alkanes We will work through the example on p 704 of you textbook.Do the practice problems on p 705 # 1-2 all.
10 Cyclic Alkanescycloalkane: alkanes where the carbon atoms are arranged in a ring (cyclic) structure-contain minimum of 3 carbonsUse the same rules for naming straight-chain alkanes, but with a few modifications:-the ring is the parent chain
11 Naming Cyclic Alkanes 1. Count the number of carbons and name as a straight-chain alkane2. Once named, place the prefix, cyclo- in front
12 Naming Cyclic AlkanesCyclic alkanes, like branched alkanes, can contain substituent groups, with each group attached being numbered with the lowest possible set of numbers♦ if there is only one substituted group, you do notneed to number it
13 We will work through the example on p 707. Naming CycloalkanesWe will work through the example on p 707.Complete practice problems #10-11 on p 708
14 Properties of Alkanes1. In general, the more carbons present in a straight-chain alkane, the higher its melting and boiling points.2. They are relative unreactive.3. Because alkanes don’t have any polar bonds, they will dissolve only those organic compounds that are nonpolar or that have low polarity, such as oils and waxes.4. Are immiscible in water because they are nonpolar.5. Readily undergo combustion in oxygen
15 Alkenesunsaturated hydrocarbon: contains one or more double or triple bonds between carbon atoms-does not have a maximum number of Halkene: has at least one double bond between carbon atoms-cannot have a one carbon alkene because you musthave at least 2 carbons for a double bond to occur-alkenes with one double bond have twice as manyhydrogens as carbons, as shown in the formulaCnH2n-look at Table 22-4 on page 711
16 Naming AlkenesAlkenes are named in much the same way as alkanes, except we change the –ane ending to –ene-examples: ethane becomes etheneH2C=CH2propane becomes propeneH2C=CH-CH3-if there are more than 4 carbons, you must state thelocation of the double bond using the lowest numberpossibleC=C-C-C is 1-butene (not 3-butene)C-C=C-C is 2-butene
17 Naming Cyclic AlkenesWhen you name cyclic alkenes, carbon number 1 must be attached to the double bond-example: cyclopentene (not 1-cyclopentene, sincethe 1 is assumed)-example: 1,3-dimethylcyclopenteneWhat if the alkene is branched?
18 Naming Branched Alkenes You name branched alkenes like branched alkanes with 2 differences:-parent chain is always the longest chain that includesthe double bond, even if it is not the longest chain ofC atoms-the position of the double bond, not the branches,that determines how the parent chain is numberedCH3Example: CH2=C-CH2-CH32-methylbuteneLets look at the example on p 713
20 More Alkane & Alkene Practice P # 61-65, 66ab, 67
21 Properties & Uses of Alkenes 1. Nonpolar, making them insoluble in water2. Relatively low melting and boiling points3. Fairly reactive (electron density around double bond)Uses1. Making plastic bags/jugs (polyethylene)2. Ripening fruit (ethylene, or ethene-fat soluble hormone)3. Making rubber (different alkenes)4. aromatics/scents
22 Alkynes Another group of unsaturated hydrocarbons are alkynes. alkyne: contains one or more C-C triple bonds-must have at least 2 carbons-are named using the same rules as naming alkenes, except with the ending –yne instead of –eneProperties of Alkynes1. Similar chemical and physical properties as alkenes, though tend to be more reactive because of the high area of electron density on the triple bond-will burn at temp >3000oC when in the presence of O2
23 Uses of AlkynesAcetylene (ethyne) torches in weldingAs a reagent in the manufacture of plastics and other organic industrial chemicalsPracticeP 716 # 21a, p 733 # 66c
24 Functional GroupsObjectives:Describe a functional group and give examples.You have learned that there are thousands of different hydrocarbons because carbon atoms can link together and form straight, branched, and cyclic compounds.However, carbon can also bond with atoms other than hydrogen or other carbon compounds; the most common are: O, N, F, Cl, Br, I, S and P
25 functional group: an atom or group of atoms that reacts in a certain way in an organic molecule. •the addition of a functional group produces acompound with different physical and chemicalproperties than the parent hydrocarbon.•there are several important functional groups youneed to know (see page 738, Table 23.1) and thefollowing:1. phosphate -PO42. sulfhydryl -SH*functional groups change the shape of a hydrocarbon molecule