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, they are also very corrosive.

Alcohols and PhenolsAlcohols can be classified into three classes:Primary (1) alcohols like ethanol have the -OH group attached to a C atom that has one bond to another C atom.

Alcohols and PhenolsSecondary(2) alcohols have the OH group attached to a C atom that has bonds to 2 other C atoms.For example,2-propanol:

Alcohols and PhenolsTertiary (3) alcohols have the OH group attached to a C atom that is bonded to 3 other C atoms.For example, 2-methyl-2-propanol

Alcohols and PhenolsThe stem for the parent hydrocarbon plus an -ol suffix is the systematic name for an alcohol. A numeric prefix indicates the position of the -OH group in alcohols with three or more C atoms. Common names are the name of the appropriate alkyl group plus alcohol.

Alcohols and PhenolsAlcohols are named using the stem for the parent hydrocarbon plus an -ol suffix in the systematic nomenclature.A numeric prefix indicates the position of the -OH group in alcohols with three or more C atoms. Common alcohol names are the name of the appropriate alkyl group plus the word alcohol.

Alcohols and PhenolsThere are several isomeric monohydric acyclic (contains no rings) alcohols that contain more than three C atoms. There are four isomeric four-carbon alcohols.

Alcohols and Phenols

Alcohols and PhenolsThere are eight isomeric five-carbon alcohols.You do it!

Alcohols and PhenolsPolyhydric alcohols contain more than one -OH group per molecule.

Alcohols and PhenolsPhenols are usually called by their common (trivial) names.

Alcohols and PhenolsPhenols are usually called by their common (trivial) names.

Alcohols and PhenolsPhenols are usually called by their common (trivial) names.

Alcohols and PhenolsPhenols are usually called by their common (trivial) names.

Alcohols and PhenolsBecause the -OH group is quite polar, the properties of alcohols depend upon the number of -OH groups per molecule and the size of the organic group.The boiling points of monohydric alcohols increase with increasing molecular weight.The solubility of monohydric alcohols in water decrease with increasing molecular weight.Polyhydric alcohols are more soluble in water because of the two or more polar groups (-OH).

EthersEthers may be thought of as derivatives of water in which both H atoms have been replaced by alkyl or aryl groups.

EthersEthers may be thought of as derivatives of water in which both H atoms have been replaced by alkyl or aryl groups.

EthersEthers may be thought of as derivatives of water in which both H atoms have been replaced by alkyl or aryl groups.

EthersEthers are not very polar and not very reactive. They are excellent solvents. Common names are used for most ethers.

Aldehydes and KetonesThe functional group in aldehydes and ketones is the carbonyl group.

Aldehydes and KetonesExcept for formaldehyde, aldehydes have one H atom and one organic group bonded to a carbonyl group.

Aldehydes and KetonesKetones have two organic groups bonded to a carbonyl group.

Aldehydes and KetonesCommon names for aldehydes are derived from the name of the acid with the same number of C atoms. IUPAC names are derived from the parent hydrocarbon name by replacing -e with -al.

Aldehydes and KetonesCommon names for aldehydes are derived from the name of the acid with the same number of C atoms. IUPAC names are derived from the parent hydrocarbon name by replacing -e with -al.

Aldehydes and KetonesCommon names for aldehydes are derived from the name of the acid with the same number of C atoms. IUPAC names are derived from the parent hydrocarbon name by replacing -e with -al.

Aldehydes and KetonesThe IUPAC name for a ketone is the characteristic stem for the parent hydrocarbon plus the suffix -one.A numeric prefix indicates the position of the carbonyl group in a chain or on a ring.

Aldehydes and KetonesThe IUPAC name for a ketone is the characteristic stem for the parent hydrocarbon plus the suffix -one.A numeric prefix indicates the position of the carbonyl group in a chain or on a ring.

Aldehydes and KetonesThe IUPAC name for a ketone is the characteristic stem for the parent hydrocarbon plus the suffix -one.A numeric prefix indicates the position of the carbonyl group in a chain or on a ring.

Aldehydes and KetonesMany aldehydes and ketones occur in nature.

AminesAmines are derivatives of ammonia in which one or more H atoms have been replaced by organic groups (aliphatic or aromatic or a mixture of both). There are three classes of amines.

AminesAmines are derivatives of ammonia in which one or more H atoms have been replaced by organic groups (aliphatic or aromatic or a mixture of both). There are three classes of amines.

AminesAmines are derivatives of ammonia in which one or more H atoms have been replaced by organic groups (aliphatic or aromatic or a mixture of both). There are three classes of amines.

AminesAmines are derivatives of ammonia in which one or more H atoms have been replaced by organic groups (aliphatic or aromatic or a mixture of both). There are three classes of amines.

AminesAniline is the simplest aromatic amine. It is much less basic than NH3. Aniline is a very important industrial chemical.

AminesHeterocylic amines have one or more N atoms in a ring structure. Many are important in living systems.

AminesHeterocylic amines have one or more N atoms in a ring structure. Many are important in living systems.

AminesHeterocylic amines have one or more N atoms in a ring structure. Many are important in living systems.

Carboxylic AcidsCarboxylic acids contain the carboxyl functional group.The general formula for carboxylic acids is:R represents an alkyl or an aryl group

Carboxylic AcidsIUPAC names for a carboxylic acid are derived from the name of the parent hydrocarbon.The final -e is dropped from the name of the parent hydrocarbonThe suffix -oic is added followed by the word acid. Many organic acids are called by their common (trivial) names which are derived from Greek or Latin.

Carboxylic Acids

Carboxylic AcidsPositions of substituents on carboxylic acid chains are indicated by numeric prefixes as in other compounds Begin the counting scheme from the carboxyl group carbon atom. They are also often indicated by lower case Greek letters. = 1st C atom = 2nd C atom = 3rd C atom, etc.

Carboxylic Acids

Carboxylic Acids

Carboxylic Acids

Carboxylic AcidsDicarboxylic acids contain two carboxyl groups per molecule.

Nomenclature of Carboxylic AcidsDicarboxylic acids contain two carboxyl groups per molecule.

Nomenclature of Carboxylic AcidsDicarboxylic acids contain two carboxyl groups per molecule.

Carboxylic AcidsAromatic acids are usually called by their common names.Sometimes, they are named as derivatives of benzoic acid which is considered to be the "parent" aromatic acid.

Carboxylic Acids

Carboxylic Acids

Carboxylic AcidsAcid strengths of simple carboxylic acids vary little with chain length.However, substituents on a carbon atom in the chain can cause large variations in acid strengths .

Carboxylic Acids

Carboxylic Acids

Carboxylic AcidsThe -OH group in the carboxyl group of carboxylic acids, is displaced in many of their reactions. The non -OH portion of a carboxylic acid is called an acyl group.

Some Derivatives of Carboxylic AcidsFour important classes of compounds contain acyl groups They are all considered to be derivatives of carboxylic acids. In these structures R's may represent either alkyl or aryl groups.

Some Derivatives of Carboxylic Acids

Some Derivatives of Carboxylic Acids

Some Derivatives of Carboxylic AcidsAcid anhydrides are related to their parent acids as follows:The word anhydride means without water.

Some Derivatives of Carboxylic AcidsAcyl halides are much more reactive, and more volatile, than their parent acids. They react with water to form their parent acids and a hydrohalic acid.

Some Derivatives of Carboxylic AcidsAcyl halides are prepared by reacting their parent acids with PCl3, PCl5, or SOCl2. The more volatile acid halide is then distilled out of the reaction mixture.

Some Derivatives of Carboxylic AcidsEsters are prepared by heating a carboxylic acid with an alcohol in the presence of a small amount of an inorganic acid. The reaction mixture will contain some ester and water, as well as unreacted acid and alcohol.

Some Derivatives of Carboxylic AcidsEsters are usually called by their common names. Many simple esters occur naturally and have pleasant odors. Esters are frequently used in fragrances and as artificial flavors.

Some Derivatives of Carboxylic AcidsFats are solid esters of glycerol and (mostly) saturated acids at room temperature. Oils are liquid esters of glycerol and primarily unsaturated acids at room temperature. The "acid" parts of fats and oils usually contain even numbers of C atoms in naturally occurring fats and oils.16 and 18 carbon chains are the most commonly found chain sizes in nature.

Some Derivatives of Carboxylic AcidsSome acids that are found (as their esters) in fats and oils include:

Some Derivatives of Carboxylic AcidsStearic acid is often found in beef fat.

Some Derivatives of Carboxylic AcidsTriglycerides are the triesters of glycerol.The common name for triglycerides is tri (acid stem) plus an -in suffix.For example, tripalmitin.

Some Derivatives of Carboxylic AcidsWaxes are esters of long chain fatty acids and alcohols other than glycerol. Commonly, waxes are derived from monohydric alcohols. Beeswax and carnauba wax are esters of myricyl alcohol, C30H61OH.

Some Derivatives of Carboxylic AcidsCarnauba wax is often used in car waxes.

Some Derivatives of Carboxylic AcidsDihydric alcohols (2 OHs per molecule) can react with dicarboxylic acids (2 COOHs per molecule) to form polyesters. Ester linkages are formed at both ends of both molecules to give polymeric esters with very high molecular weights.

Some Derivatives of Carboxylic Acids

Some Derivatives of Carboxylic AcidsAmides are derivatives of organic acids and primary or secondary amines. The functional groups of amides are:

Some Derivatives of Carboxylic AcidsAmides are also named as derivatives of carboxylic acids. The suffix -amide is substituted for -ic acid or -oic acid.

Some Derivatives of Carboxylic AcidsWhen an aryl or alkyl substituent is present on the N atom, the letter N and the name of the substituent are prefixed to the name of the unsubstituted amide.

Some Derivatives of Carboxylic AcidsAcetaminophen Tylenol - is an amide.

Summary of the Functional GroupsA summary of the functional groups is:

Substitution ReactionsIn a substitution reaction an atom or group of atoms attached to a carbon atom is replaced (substituted for) by another atom or group of atoms. There is no change in the degree of saturation at the reactive carbon atom.Halogenation reactions are an important class of substitution reactions. Chlorine reacts with alkanes in free radical chain reactions (also substitution reactions).

Substitution ReactionsFree radical chain reactionsThe halogenation of methane is one example.

Substitution Reactions

Substitution Reactions

Substitution ReactionsFree radical chain reactionsMany substitution reactions of alkanes produce more than one product.

Substitution Reactions

Substitution Reactions

Substitution ReactionsNitration reaction of an aromatic hydrocarbon replaces an H atom attached to an aromatic ring with a nitro, -NO2, group.

Addition ReactionsAn addition reaction involves an increase in the number of groups attached to carbon. The degree of saturation of the molecule is increased.

Addition ReactionsHydrogenation is a very important kind of addition reaction.Hydrogenation is used to convert unsaturated fats and oils to saturated fats or oils.

Elimination ReactionsAn elimination reaction involves the removal of groups attached to carbon.The degree of unsaturation increases.

Elimination ReactionsDehydration is an important kind of elimination reaction.

Polymerization ReactionsA polymer is a large molecule that consists of a high-molecular weight chain of small molecules.The small molecules that have been joined to form the polymer are called monomers.Synthetic polymers are a relatively new class of molecules.The first one, bakelite, was discovered in 1909.Nylon, which is still extensively used, was discovered in 1930s.

Polymerization ReactionsAddition polymerization is a large commercial process in the United States. Polyethylene is the addition polymer made in the largest quantities in the United States.Polyethylene is used to make Coke bottles, plastic bags, etc.

Polymerization ReactionsAddition polymerizationPolyethylene formation

Polymerization ReactionsAddition polymerizationTeflon is the material used in nonstick frying pans and other kitchen utensils.

Polymerization ReactionsFormation of rubberNatural rubber is a polymer made of isoprene (2-methyl-1,3-butadiene) units that form a unique stereoisomeric structure.

Polymerization ReactionsVulcanization of rubberNatural rubber is a sticky, soft compound when heated which limited its commercial potential.Charles Goodyear discovered in 1839 that heating rubber with sulfur removed the stickiness and made the substance elastic.This is the basis of modern tire production.Vulcanization provides disulfide cross-linking bonds between the isoprene units.

Polymerization ReactionsCopolymersIf two different monomers are mixed and the polymerized, copolymers are formed.Styrene butadiene rubber - SBR - is an important copolymer used in tire production.

Polymerization ReactionsCopolymers

Polymerization Reactions

Polymerization ReactionsCondensation PolymersCondensation polymers occur when two molecules react and eliminate a small molecule.Molecules eliminated commonly are water and HCl.Important condensation polymers include nylon, dacron, and kevlar.Dacron is used in clothing to make it wrinkle free. Blood does not clot in contact with dacron thus it is used in artificial arteries.

Polymerization ReactionsCondensation PolymersDacron formation

Polymerization Reactions

Polymerization ReactionsCondensation PolymersNylon was first made by Wallace Carothers in the 1930s.Nylon is widely used in a variety of commercial products including stockings, rope, guitar strings, fire-proof clothing.

Polymerization ReactionsCondensation PolymersNylon 66 formation

Polymerization Reactions

Synthesis QuestionTNT, the explosive ingredient in dynamite, has the correct name of 2,4,6-trinitrotoluene. Draw the structure of TNT.

Synthesis Question

Group QuestionAerobic respiration produces carbon dioxide and water as its end products. Anaerobic respiration has different end products. What are the end products of anaerobic respiration? How could you easily detect that someone has switched from aerobic to anaerobic respiration?

End of Chapter 27There are more organic compounds than any other type of chemical species.