Chapter 25 Organic Chemistry I: Compounds. 2 Chapter Goals Saturated Hydrocarbons 1.Alkanes and...

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Transcript of Chapter 25 Organic Chemistry I: Compounds. 2 Chapter Goals Saturated Hydrocarbons 1.Alkanes and...

  • Chapter 25Organic Chemistry I: Compounds

  • Chapter GoalsSaturated HydrocarbonsAlkanes and CycloalkanesNaming Saturated HydrocarbonsUnsaturated Hydrocarbons AlkenesAlkynesAromatic HydrocarbonsBenzeneOther Aromatic HydrocarbonsHydrocarbons: A Summary

  • Chapter GoalsFunctional GroupsOrganic HalidesAlcohols and PhenolsEthers Aldehydes and KetonesAminesCarboxylic AcidsSome Derivatives of Carboxylic AcidsSummary of Functional Groups

  • Chapter GoalsFundamental Classes of Organic ReactionsSubstitution ReactionsAddition ReactionsElimination Reactions Polymerization Reactions

  • Saturated HydrocarbonsHydrocarbons are chemical compounds that contain only C and H atoms.Saturated hydrocarbons contain only single or sigma () bonds.There are no double or triple bonds in these compounds.The primary source of hydrocarbons is petroleum and natural gas.

  • Alkanes and CycloalkanesThe simplest saturated hydrocarbons are called alkanes.Methane, CH4, is the simplest alkane.The alkanes form a homologous series.Each member of the series differs by a specific number and kind of atoms.

  • Alkanes and CycloalkanesThe alkanes differ from each other by a CH2 or methylene group.All alkanes have this general formula.CnH2n+2For example ethane, C2H6 , and propane, C3H8 , are the next two family members.

  • Alkanes and CycloalkanesIsomers are chemical compounds that have the same molecular formulas but different structures.Two alkanes have the molecular formula C4H10. They are a specific type of isomer called structural isomers.

  • Alkanes and CycloalkanesThree alkanes have the formula C5H12.There are three structural isomers of pentane.

  • Alkanes and CycloalkanesThree alkanes have the formula C5H12.There are three structural isomers of pentane.

  • Alkanes and CycloalkanesThree alkanes have the formula C5H12.There are three structural isomers of pentane.

  • Alkanes and CycloalkanesThere are five isomeric hexanes, C6H14.You draw them!

  • Alkanes and CycloalkanesThere are five isomeric hexanes, C6H14.

  • Alkanes and CycloalkanesThere are five isomeric hexanes, C6H14.

  • Alkanes and CycloalkanesThere are five isomeric hexanes, C6H14.

  • Alkanes and CycloalkanesThere are five isomeric hexanes, C6H14.

  • Alkanes and CycloalkanesThe number of structural isomers increases rapidly with increasing numbers of carbon atoms.The boiling points of the alkanes increase with molecular weight.

  • Alkanes and CycloalkanesCyclic saturated hydrocarbons are called cycloalkanes. They have the general formula CnH2n. Some examples are:

  • Alkanes and CycloalkanesCyclic saturated hydrocarbons are called cycloalkanes. They have the general formula CnH2n. Some examples are:

  • Alkanes and CycloalkanesCyclic saturated hydrocarbons are called cycloalkanes. They have the general formula CnH2n. Some examples are:

  • Naming Saturated HydrocarbonsThe International Union of Pure and Applied Chemistry (IUPAC) names for the first 12 "straight-chain" or "normal" alkanes are given in this table.

  • Naming Saturated Hydrocarbons

    Number of carbon atoms in chainName7Heptane8Octane9Nonane10Decane11Unidecane12Dodecane

  • Naming Saturated HydrocarbonsOther organic compounds are named as derivatives of the alkanes.Branched-chain alkanes are named by the following rules.Choose the longest continuous chain of carbon atoms which gives the basic name or stem.

  • Naming Saturated HydrocarbonsNumber each carbon atom in the basic chain, starting at the end that gives the lowest number to the first group attached to the main chain (substituent).For each substituent on the chain, we indicate the position in the chain (by an Arabic numeric prefix) and the kind of substituent (by its name). The position of a substituent on the chain is indicated by the lowest number possible.The number precedes the name of the substituent.

  • Naming Saturated HydrocarbonsWhen there are two or more substituents of a given kind, use prefixes to indicate the number of substituents.di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa = 8, and so on.The combined substituent numbers and names serve as a prefix for the basic hydrocarbon name.Separate numbers from numbers by commas and numbers from words by hyphens. Words are "run together".

  • Naming Saturated HydrocarbonsAlkyl groups (represented by the symbol R) are common substituents. Alkyl groups are fragments of alkanes in which one H atom has been removed for the connection to the main chain.Alkyl groups have the general formula CnH2n+1. In alkyl groups the -ane suffix in the name of the parent alkane is replaced by -yl. A one carbon group is named methyl.A two carbon group is named ethyl.A three carbon group is named propyl.

  • Unsaturated HydrocarbonsThe three classes of unsaturated hydrocarbons are:alkenes and cycloalkenes, CnH2nalkynes and cycloalkynes, CnH2n-2aromatic hydrocarbons

  • AlkenesThe simplest alkenes contain one C=C bond per molecule. The general formula for simple alkenes is CnH2n.The first two alkenes are:ethene, C2H4

  • AlkenesThe simplest alkenes contain one C=C bond per molecule. The general formula for simple alkenes is CnH2n.The first two alkenes are:and propene, C3H6

  • AlkenesEach doubly bonded C atom is sp2 hybridized.The sp2 hybrid consists of:two s bonds (single bonds) andone s and one p bond (double bond)

  • AlkenesThe systematic naming system for alkenes uses the same stems as alkanes.In the IUPAC system, the -ane suffix for alkanes is changed to -ene. Common names for the alkenes have the same stem but use the suffix -ylene is used. In chains of four or more C atoms, a numerical prefix shows the position of the lowest-numbered doubly bonded C atom. Always choose the longest chain that contains the C=C bond.

  • AlkenesPolyenes contain two or more double bonds per molecule. Indicate the number of double bonds with suffixes: -adiene for two double bonds.-atriene for three double bonds, etc.The positions of the substituents are indicated as for alkanes. The position of the C=C bond(s) is/are given the lowest number(s) possible.

  • Alkenes

  • Alkenes

  • Alkenes

  • CycloalkenesCycloalkenes have the general formula CnH2n-2. Examples are:cyclopentene

  • Cycloalkenescyclohexene

  • Cycloalkenescycloheptene

  • AlkynesAlkynes contain CC bonds. The simplest alkyne is C2H2, ethyne, or acetylene.Alkynes with only one C C bond have the formula CnH2n-2.Each carbon atom in a C C bond is sp hybridized.Each sp hybrid contains two bonds and two bonds.The carbon atom will have one single bond and one triple bond.

  • AlkynesAlkynes are named like the alkenes except that the suffix -yne is used with the characteristic stem The alkyne stem is derived from the name of the alkane with the same number of carbon atoms.

  • AlkynesAcetylene is an important industrial chemical. It is prepared by the reaction of calcium carbide with water.

  • AlkynesAcetylene burns in a highly exothermic reactionThe combustion produces temperatures of about 3000C.Acetylene is used in cutting torches for welding.Alkynes are very reactive The two p bonds are sights of special reactivity.Addition reactions, such as hydrogenation, are common.

  • Hydrocarbons: A Summary

  • Aromatic HydrocarbonsHistorically, aromatic was used to describe pleasant smelling substances. Now it refers to benzene, C6H6, and derivatives of benzene.Other compounds that have similar chemical properties to benzene are also called aromatic.

  • BenzeneThe structure of benzene, C6H6, is:

  • Other Aromatic HydrocarbonsCoal tar is the common source of benzene and many other aromatic compounds.Some aromatic hydrocarbons that contain fused rings are:napthalene

  • Other Aromatic Hydrocarbonsphenanthrene

  • Other Aromatic HydrocarbonsMany aromatic hydrocarbons contain alkyl groups attached to benzene rings (as well as to other aromatic rings). The positions of the substituents on benzene rings are indicated by the prefixes:ortho-(o-) for substituents on adjacent C atomsmeta-(m-) for substituents on C atoms 1 and 3para-(p-) for substituents on C atoms 1 and 4

  • Other Aromatic Hydrocarbons

  • Functional GroupsFunctional groups are groups of atoms that represent potential reaction sites.Compounds that contain a given functional group usually undergo similar reactions.Functional groups influence physical properties as well.

  • Organic HalidesA halogen atom may replace almost any hydrogen atom in a hydrocarbon.The functional group is the halide (-X) group. Examples include:chloroform, CHCl3

  • Organic Halides1,2-dichloroethane, ClCH2CH2Cl

  • Organic Halidespara-dichlorobenzene

  • Alcohols and PhenolsThe functional group in alcohols and phenols is the hydroxyl (-OH) group. Alcohols and phenols can be considered derivatives of hydrocarbons in which one or more H atoms have been replaced by -OH groups. Phenols are derivatives of benzene in which one H has been replaced by replaced by -OH group.

  • Alcohols and PhenolsEthyl alcohol (ethanol), C2H5OH, is the most familiar alcohol.

  • Alcohols and PhenolsPhenol, C6H5OH, is the most familiar phenol.

  • Alcohols and PhenolsAlcohols are considered neutral compounds because they are only very slightly acidic.Alcohols can behave as acids but only in the presence of very strong bases.Phenols are weakly acidic.Ka 1.0 x 10-10 for phenolAlthough phenols are very weakly acidic