organic-compounds.pptx

organic compoundshydrocarbonsn nThe term organic appears to have been used for The term organic appears to have been used for the first time about 1777 and was applied to those the first time about 1777 and was applied to those materials occurring in or derived from living materials occurring in or derived from living organisms.Accordingly,such substances as starch,organisms.Accordingly,such substances as starch,alcohol,and urea were classified as organic,for alcohol,and urea were classified as organic,for starch is produced by living plants,alcohol is a starch is produced by living plants,alcohol is a product of fermentation caused by product of fermentation caused by microorganisms,and urea is contained in urine.In microorganisms,and urea is contained in urine.In 1824,however,the German chemist W1824,however,the German chemist Whler hler synthesized urea,and the original meaning of the synthesized urea,and the original meaning of the term term“organicorganic”no longer applied.Organic no longer applied.Organic compounds,in the modern sense,are the compounds,in the modern sense,are the compounds of carbon.Many thousands of carbon compounds of carbon.Many thousands of carbon compounds which are not found in or derived compounds which are not found in or derived from living organisms have been produced by from living organisms have been produced by chemists,and well over a million organic chemists,and well over a million organic compounds are already pounds are already known.The existence of so many organic compounds is due The existence of so many organic compounds is due primarily to the ability of carbon atoms to combine primarily to the ability of carbon atoms to combine with other carbon atoms,forming chains of different with other carbon atoms,forming chains of different lengths and rings of different sizes.The elements,lengths and rings of different sizes.The elements,other than carbon,most frequently found in organic other than carbon,most frequently found in organic compounds are hydrogen,oxygen,nitrogen,sulfur,compounds are hydrogen,oxygen,nitrogen,sulfur,the halogens,phosphorus,and some of the metals.the halogens,phosphorus,and some of the metals.Although the number of organic compounds is Although the number of organic compounds is vast,the study of organic chemistry is greatly vast,the study of organic chemistry is greatly simplified by the fact that the chemistry of carbon simplified by the fact that the chemistry of carbon compounds can be organized around compounds can be organized around“functional functional groupsgroups”,each of which imparts similarities in,each of which imparts similarities in chemical properties.chemical properties.Hydrocarbonsn n The simplest organic compounds are those containing only carbon and hydrogen.Such compounds are known as hydrocarbon.Some of them are found in nature,where they were derived from plant or animal forms of life.Several types of hydrocarbons are possible.The alkanesn nThe series of compounds which have the general The series of compounds which have the general empirical formula Cempirical formula Cn nH H2 2n+n+2 2,where,where n n is an integer,is is an integer,is called the alkane,or paraffin.called the alkane,or paraffin.n nThe lighter members of the alkane series are gases,the The lighter members of the alkane series are gases,the members of intermediate weight are liquids,and the members of intermediate weight are liquids,and the heavier members are solids.From the formulas of the heavier members are solids.From the formulas of the compounds it is evident that each member differs from compounds it is evident that each member differs from the preceding one by the increment CHthe preceding one by the increment CH2 2.A series of.A series of compounds in which each member differs from the one compounds in which each member differs from the one before it by a common increment is called a homologous before it by a common increment is called a homologous series.series.The electronic formulas for methane,ethane,and propane are easily written.Although the electronic formula representation makes the molecules seem planar,it must be remembered that in all the alkanes the CC and CH bonds have the geometrical arrangement set by the tetrahedral configuration of each carbon unit.MethaneMethane Pentane PentaneThere are two hydrocarbons having the formula There are two hydrocarbons having the formula C C4 4HH1010,and these are known as normal butane and,and these are known as normal butane and isobutane.The two butanes are isomers.They have isobutane.The two butanes are isomers.They have the same empirical formula,and hence the same the same empirical formula,and hence the same composition,but different physical and chemical composition,but different physical and chemical properties,because they differ in the arrangement of properties,because they differ in the arrangement of the atoms in their molecules.Normal butane,the atoms in their molecules.Normal butane,n n-butane,is a butane,is a“straight chainstraight chain”molecule and molecule and isobutane is a isobutane is a“branched chainbranched chain”molecule.The molecule.The number of possible isomers increases with increasing number of possible isomers increases with increasing molecular weight;the hydrocarbon of large molecular weight;the hydrocarbon of large molecular weight have great numbers of isomers.molecular weight have great numbers of isomers.Alkanes are characterized by being rather unreactive chemically;hence,the use of the name paraffin,which means“having little affinity”.The following reaction is a typical one for the alkanes and is referred to as a substitution reaction.(heat or UV lightheat or UV light)CH4+Cl2=CH3Cl+HClThis reaction is a chain reaction which proceeds in several steps.An important point concerning this particular reaction is that it transforms an alkane molecule into one which has a more reactive“functional group”on ita halogen in this specific case.The functional group makes it possible for the molecule to take part in many different kinds of reactions.Another very important reaction of alkanes is based upon their ability to burn in air in a highly exothermic oxidation-reduction reaction.A typical combustion reaction is that for ethane.(2C2H6+O2=4CO2+6H2O)Methane is the principal component of natural gas.Gasoline is a mixture of straight and branched chain alkanes containing 59 carbon atoms plus various additives.Kerosene,diesel oil,and fuel oil are primarily mixtures of alkanes with higher molecular weights.The alkenesn Hydrocarbon molecules which contain a double bond are members of a second homologous series,referred to as alkenes.The two carbon atoms linked by a double bond are bound together by two kinds of bonds,one sigma CC bond and one pi CC bond.n The alkenes have the general empirical formula CnH2n.ethylene,C2H4,the simplest alkene,has a trigonal planar structure.The second member of the series is propylene and then come the butene isomers.The series builds up in a manner analogous to the alkane series.In writing formulas for members of the ethylene series,the two shared electron pairs are usually represented by two lines.Note that carbon atoms with single bonds have sp3 hybridization,and those with double bonds have sp2 hybridization.Actually,two isomers of 2-butene exist,because the double bond is quite rigid and hence rotation about it is very difficult.Writing the formulas for the butene molecules in a slightly different fashion makes it possible to show the three butene isomers more clearly.Alkenes are much more reactive than alkanes.The Alkenes are much more reactive than alkanes.The bond,being a relatively weaker bond,is disrupted bond,being a relatively weaker bond,is disrupted much more easily than a bond.Thus,the reactions much more easily than a bond.Thus,the reactions characteristic of alkenes are those in which the characteristic of alkenes are those in which the bond is broken.bond is broken.In the presence of a suitable catalyst(Pt,Pd,or Ni,In the presence of a suitable catalyst(Pt,Pd,or Ni,for example),alkenes add hydrogen to form the for example),alkenes add hydrogen to form the corresponding alkanes.corresponding alkanes.Chlorine breaks the double bond and adds to the Chlorine breaks the double bond and adds to the two carbons adjacent to the double bond in the two carbons adjacent to the double bond in the alkenes,instead of replacing a hydrogen as in the alkenes,instead of replacing a hydrogen as in the alkanes.alkanes.Many other reagents react with alkenes by breaking Many other reagents react with alkenes by breaking the double bond.An example is the acid-catalyzed the double bond.An example is the acid-catalyzed addition of water to an alkene.addition of water to an alkene.A very important property of the alkenes is their A very important property of the alkenes is their ability to add to themselves.This reaction is a very ability to add to themselves.This reaction is a very significant one in the plastics industry.significant one in the plastics industry.Because ethylene and the other alkenes have the Because ethylene and the other alkenes have the ability to add chlorine and other atoms,they are ability to add chlorine and other atoms,they are called unsaturated compounds.On the other hand,called unsaturated compounds.On the other hand,ethane and the other alkanes react with chlorine by ethane and the other alkanes react with chlorine by substitution only,so they are called saturated substitution only,so they are called saturated pounds.Ethylene is a colorless gas with a rather sweet odor.It occurs in natural gas and is formed when coal or wood is submitted to destructive distillation.Ethylene,mixed with oxygen,is used as an anesthetic in dentistry and surgery.It has the interesting property of causing green fruits to ripen and is used commercially for this purpose.The production of 11,790,000 tons of ethylene in 1974 made it fifth highest of all chemicals produced in the United States for that year.The alkynesn n Hydrocarbon molecules which contain the triple bond are called alkynes;they make up another series of unsaturated hydrocarbons.Two carbon atoms joined by a triple bond are bound together by one sigma CC bond and two pi CC bonds.The alkynes have the general empirical formula Cn nH2 2n-n-2 2.The simplest and most important member of the The simplest and most important member of the alkyne homologous series is acetylene,Calkyne homologous series is acetylene,C2 2HH2 2.The.The electronic and line formulas for acetylene are electronic and line formulas for acetylene are H:C:C:H H-CH:C:C:H H-CC-H C-H.Acetylene is liberated when calcium carbide is Acetylene is liberated when calcium carbide is treated with water.treated with water.Chemically,the alkynes are similar to alkenes Chemically,the alkynes are similar to alkenes except that with two bonds they react even more except that with two bonds they react even more readily,adding twice as much reagent in addition readily,adding twice as much reagent in addition reactionsreactions.The reaction of acetylene with bromine is The reaction of acetylene with bromine is a typical example.a typical example.Acetylene and all the other alkynes burn very Acetylene and all the other alkynes burn very easily.easily.The triple bond is a high energy bond,and this The triple bond is a high energy bond,and this energy is released when the compound is energy is released when the compound is transformed into carbon dioxide and water.Thus,transformed into carbon dioxide and water.Thus,the flame produced by burning acetylene is very hot;the flame produced by burning acetylene is very hot;it is used in welding and cutting metal.When it is used in welding and cutting metal.When acetylene burns,some of it breaks down a second acetylene burns,some of it breaks down a second way according to the equation Cway according to the equation C2 2HH2 22C+H2C+H2 2.At the.At the temperature of the flame,the particles of carbon temperature of the flame,the particles of carbon become heated to incandescence;i.e.,they give off a become heated to incandescence;i.e.,they give off a brilliant luminous white light.At one time,acetylene brilliant luminous white light.At one time,acetylene was used to light homes and in lamps for bicycles was used to light homes and in lamps for bicycles and automobiles.and automobiles.Cyclic hydrocarbonsbenzenen nIt is possible to introduce three double bonds into the It is possible to introduce three double bonds into the cyclohexane ring.If this experiment is performed,it cyclohexane ring.If this experiment is performed,it is found that the compound which is formed has is found that the compound which is formed has unique chemical properties,not very much like an unique chemical properties,not very much like an alkene.We could call the product cyclohexatriene,but alkene.We could call the product cyclohexatriene,but it actually is named benzene.The empirical formula it actually is named benzene.The empirical formula is Cis C6 6H H6 6.n nThe unique properties of benzene are related to its The unique properties of benzene are related to its molecular orbital structure.As can be surmised from molecular orbital structure.As can be surmised from the structural formula above,all the carbons in the structural formula above,all the carbons in benzene are benzene are spsp2 2 hybridized.The three hybridized.The three spsp2 2 hybrid hybrid orbitals lie in a plane,and hence the benzene orbitals lie in a plane,and hence the benzene molecule is planar.molecule is planar.Benzene,a volatile liquid,is the first and best known Benzene,a volatile liquid,is the first and best known member of another homologous series in which each member of another homologous series in which each member differs from its predecessor by the increment CHmember differs from its predecessor by the increment CH2 2.Benzene and its homologs,which have one ring,have the Benzene and its homologs,which have one ring,have the general formula Cgeneral formula Cn nHH2 2nn-6 6.Compounds of his series are in a.Compounds of his series are in a class called aromatic hydrocarbons,because many of them class called aromatic hydrocarbons,because many of them have pleasant odors(though most are poisonous and have pleasant odors(though most are poisonous and should be smelled gently,if at all).should be smelled gently,if at all).If one hydrogen atom on each of two different carbon If one hydrogen atom on each of two different carbon atoms of benzene is replaced by a CHatoms of benzene is replaced by a CH3 3 group,the product group,the product is xylene.Thus,xylene may be thought of as a derivative of is xylene.Thus,xylene may be thought of as a derivative of benzene.Xylene has three isomers since substitutions to benzene.Xylene has three isomers since substitutions to introduce the two CHintroduce the two CH3 3 groups may be made in three groups may be made in t