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Organic Chemistry Objectives

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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 molecules Classified as: alkanes, alkenes, alkynes, aromatics

3 Alkanes alkane: hydrocarbon containing only C-C single bonds (-ane ending) -saturated hydrocarbon: each carbon contains a maximum of 4 single covalent bonds with other atoms -can be shown as straight chains, branched chains, or cyclic chains -follows the formula: CnH2n+2 example: if n = 1, then C1H2(1)+2 to give CH4

4 Unbranched Alkanes C-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 C eth- 2 C hept- 7 C prop- 3 C oct- 8 C but- 4 C non- 9 C pent- 5 C dec- 10 C 2. Follow the prefix with the ending, -ane Example: C8H18 is named octane Hint: 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 Alkanes Name is derived from a straight-chain alkane by replacing one or more of the hydrogen atoms by alkyl groups (which are substitued for one or more H’s) 1. a suffix that identifies the parent straight-chain alkane ♦count the number of C atoms in the longest continuous chain 2. a prefix that identifies the branching alkyl group and the number 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 second carbon The name is: 2,2-dimethylpropane Branched 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 Alkanes cycloalkane: alkanes where the carbon atoms are arranged in a ring (cyclic) structure -contain minimum of 3 carbons Use 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 alkane 2. Once named, place the prefix, cyclo- in front

12 Naming Cyclic Alkanes Cyclic 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 not need to number it

13 We will work through the example on p 707.
Naming Cycloalkanes We will work through the example on p 707. Complete practice problems #10-11 on p 708

14 Properties of Alkanes 1. 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 Alkenes unsaturated hydrocarbon: contains one or more double or triple bonds between carbon atoms -does not have a maximum number of H alkene: has at least one double bond between carbon atoms -cannot have a one carbon alkene because you must have at least 2 carbons for a double bond to occur -alkenes with one double bond have twice as many hydrogens as carbons, as shown in the formula CnH2n -look at Table 22-4 on page 711

16 Naming Alkenes Alkenes are named in much the same way as alkanes, except we change the –ane ending to –ene -examples: ethane becomes ethene H2C=CH2 propane becomes propene H2C=CH-CH3 -if there are more than 4 carbons, you must state the location of the double bond using the lowest number possible C=C-C-C is 1-butene (not 3-butene) C-C=C-C is 2-butene

17 Naming Cyclic Alkenes When you name cyclic alkenes, carbon number 1 must be attached to the double bond -example: cyclopentene (not 1-cyclopentene, since the 1 is assumed) -example: 1,3-dimethylcyclopentene What 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 includes the double bond, even if it is not the longest chain of C atoms -the position of the double bond, not the branches, that determines how the parent chain is numbered CH3 Example: CH2=C-CH2-CH3 2-methylbutene Lets look at the example on p 713

19 Naming Alkenes Practice
P 716 # 21 b & d

20 More Alkane & Alkene Practice
P # 61-65, 66ab, 67

21 Properties & Uses of Alkenes
1. Nonpolar, making them insoluble in water 2. Relatively low melting and boiling points 3. Fairly reactive (electron density around double bond) Uses 1. 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 –ene Properties of Alkynes 1. 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 Alkynes Acetylene (ethyne) torches in welding As a reagent in the manufacture of plastics and other organic industrial chemicals Practice P 716 # 21a, p 733 # 66c

24 Functional Groups Objectives: 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 a compound with different physical and chemical properties than the parent hydrocarbon. •there are several important functional groups you need to know (see page 738, Table 23.1) and the following: 1. phosphate -PO4 2. sulfhydryl -SH *functional groups change the shape of a hydrocarbon molecule

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