PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Slide 68Slide 691Introduction•Recall that alkanes are aliphatic hydrocarbons having C—C and C—H bonds. They can be categorized as acyclic or cyclic.•Acyclic alkanes have the molecular formula CnH2n+2 (where n = an integer) and contain only linear and branched chains of carbon atoms. They are also called saturated hydrocarbons because they have the maximum number of hydrogen atoms per carbon.•Cycloalkanes contain carbons joined in one or more rings. Because their general formula is CnH2n, they have two fewer H atoms than an acyclic alkane with the same number of carbons.Alkanes2•All C atoms in an alkane are surrounded by four groups, making them sp3 hybridized and tetrahedral, and all bond angles are 109.5°.•The 3-D representations and ball-and-stick models for these alkanes indicate the tetrahedral geometry around each C atom. In contrast, the Lewis structures are not meant to imply any 3-D arrangement. Additionally, in propane and higher molecular weight alkanes, the carbon skeleton can be drawn in a variety of ways and still represent the same molecule.3•The three-carbon alkane CH3CH2CH3, called propane, has a molecular formula C3H8. Note in the 3-D drawing that each C atom has two bonds in the plane (solid lines), one bond in front (on a wedge) and one bond behind the plane (on a dashed line).4•Additionally, in propane and higher molecular weight alkanes, the carbon skeleton can be drawn in a variety of ways and still represent the same molecule. For example, the three carbons of propane can be drawn in a horizontal row or with a bend. These representations are equivalent.•In a Lewis structure, the bends in a carbon chain don’t matter.5•There are two different ways to arrange four carbons, giving two compounds with molecular formula C4H10, named butane and isobutane.•Butane and isobutane are isomers—two different compounds with the same molecular formula. Specifically, they are constitutional or structural isomers.•Constitutional isomers differ in the way the atoms are connected to each other.6•Carbon atoms in alkanes and other organic compounds are classified by the number of other carbons directly bonded to them.7•Hydrogen atoms are classified as primary (1°), secondary (2°), or tertiary (3°) depending on the type of carbon atom to which they are bonded.8•The maximum number of possible constitutional isomers increases dramatically as the number of carbon atoms in the alkane increases. For example, there are 75 possible isomers for an alkane having 10 carbon atoms, but 366,319 possible isomers for one having 20 carbons.•The suffix “ane” identifies a molecule as an alkane.•By increasing the number of carbons in an alkane by a CH2 group, one obtains a “homologous series” of alkanes, as shown in Table 4.1. The CH2 group is called “methylene.”910CycloalkanesCycloalkanes have molecular formula CnH2n and contain carbon atoms arranged in a ring. Simple cycloalkanes are named by adding the prefix cyclo- to the name of the acyclic alkane having the same number of carbons.11NomenclatureThe name of every organic molecule has 3 parts:1. The parent name indicates the number of carbons in the longest continuous chain.2. The suffix indicates what functional group is present.3. The prefix tells us the identity, location, and number of substituents attached to the carbon chain.12•Carbon substituents bonded to a long carbon chain are called alkyl groups.•An alkyl group is formed by removing one H atom from an alkane.•To name an alkyl group, change the –ane ending of the parent alkane to – yl. Thus, methane (CH4) becomes methyl (CH3-) and ethane (CH3CH3) becomes ethyl (CH3CH2-).13Naming three- or four-carbon alkyl groups is more complicated because the parent hydrocarbons have more than one type of hydrogen atom. For example, propane has both 1° and 2° H atoms, and removal of each of these H atoms forms a different alkyl group with a different name, propyl or isopropyl.141. Find the parent carbon chain and add the suffix.Note that it does not matter if the chain is straight or it bends.15Also note that if there are two chains of equal length, pick the chain with more substituents. In the following example, two different chains in the same alkane have seven C atoms. We circle the longest continuous chain as shown in the diagram on the left, since this results in the greater number of substituents.162. Number the atoms in the carbon chain to give the first substituent the lowest number.17If the first substituent is the same distance from both ends, number the chain to give the second substituent the lower number.18When numbering a carbon chain results in the same numbers from either end of the chain, assign the lower number alphabetically to the first substituent.193. Name and number the substituents.•Name the substituents as alkyl groups.•Every carbon belongs to either the longest chain or a substituent, not both.•Each substituent needs its own number.•If two or more identical substituents are bonded to the longest chain, use prefixes to indicate how many: di- for two groups, tri- for three groups, tetra- for four groups, and so forth.204. Combine substituent names and numbers + parent and suffix.•Precede the name of the parent by the names of the substituents.•Alphabetize the names of the substituents, ignoring all prefixes except iso, as in isopropyl and isobutyl.•Precede the name of each substituent by the number that indicates its location. •Separate numbers by commas and separate numbers
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