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Ch. 3 Review: Nomenclature: Organic Compounds Compounds of carbon--organic chemistry –If they have only C and H, hydrocarbons –e.g. alkanes: methane CH.

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Presentation on theme: "Ch. 3 Review: Nomenclature: Organic Compounds Compounds of carbon--organic chemistry –If they have only C and H, hydrocarbons –e.g. alkanes: methane CH."— Presentation transcript:

1 Ch. 3 Review: Nomenclature: Organic Compounds Compounds of carbon--organic chemistry –If they have only C and H, hydrocarbons –e.g. alkanes: methane CH 4, ethane C 2 H 6, propane C 3 H 8 general formula: C n H 2n+2 –Know Table 3.7 Functional Groups –R = hydrocarbon group –e.g. alcohols: methanol CH 3 OH, ethanol C 2 H 5 OH –e.g. amines: propyl amine, butylamine –Know functional groups in Table 3.8 Methanol (wood alcohol), CH 3 OH, is related to methane, CH 4, by replacing one H with OH.

2 Organic chemistry -- Chapter 20 Introductory Topics Bonding & Structure -- Review Chapters 3, 9, and 10!! Types of Chemical Formulas e.g. 2-propanol (iso-propanol) !!! Always FOUR BONDS to Carbon !!! expanded structural formula or condensed structural formula fully condensed structural formula (missing C’s and H’s are understood) “line drawing”

3 Isomerism Isomers– different molecules with the same molecular formula Structural isomers--different pattern of atom attachment; different connectivity Stereoisomers—same atom attachments (connectivity), different spatial orientation Rotation about a single bond is not isomerism!!

4 Structural Isomers Structural Isomers -- same chemical formula, but different arrangement (connectivity) of atoms e.g. C 3 H 8 O - 3 isomers (2 alcohols, 1 ether) Number of possible isomers can be very large, e.g. C3H8C3H8 C 4 H 10 C 5 H 12 C 6 H 14 C 8 H 18 C 10 H 22 C 20 H 42 1 2 3 5 18 75 > 10 5 1-propanol 2-propanol ethyl methyl ether

5 Stereoisomers Stereoisomers—same atom attachments (connectivity), different spatial orientation Optical isomers (enantiomers)—are molecules that are nonsuperimposable mirror images of each other Geometric isomers—are stereoisomers that are not optical isomers, e.g. cis and trans

6 Chiral Molecules Are molecules that have nonsuperimposable mirror images –If 4 different groups are attached to carbon, it will be chiral –Chiral molecules will rotate plane-polarized light –Most physical properties are identical, but in a chiral environment enantiomers behave differently

7 7 Isomerism; Overview

8 Many Possible Compounds A Tremendous Variety of organic molecular structures and properties are possible, e.g.: vinyl chloride poly(vinyl chloride) “PVC” acetic acid aspirin

9 More Organic Compounds Caffeine C 8 H 10 N 4 O 2 methylamine fortunately, the subject is very systematic ! and is readily classified by “organic functional groups”

10 Hydrocarbons AlkanesC n H 2n+2 CH 4 methane C 5 H 12 pentane C 2 H 6 ethane C 6 H 14 hexane C 3 H 8 propane C 7 H 16 heptane C 4 H 10 butane C 8 H 18 octane, etc…. alkyl groups: methyl CH 3 ethyl CH 3 CH 2 phenyl C 6 H 5

11 Alkane Nomenclature 1.Name parent chain--longest continuous chain 2.Number parent chain -- First branch gets lowest possible number 3.Name & number branches 4.Order branches -- Alphabetical order -- Multiple identical substituents get prefix CH 3 CH 2 CHCHCHCH 2 CHCH 3 CH 3 CH 2 CH 3 5-ethyl-2,4,6-trimethyloctane5-bromo-2-cyano-4-methylheptane Samples: (see book for detailed “rules” and other functional groups)

12 Reactions of Alkanes (generally unreactive) Combustion -- fuels! e.g. C 5 H 12(l) + 8 O 2(g) --> 5 CO 2(g) + 6 H 2 O (l) Free radical substitution (not selective!) C 2 H 6(g) + Cl 2(g) --> C 2 H 5 Cl (g) + HCl (g) Dehydrogenation (reverse rxn is more common!) C 2 H 6(g) --> H 2 C=CH 2(g) + H 2(g) “Cracking” of hydrocarbons (petroleum industry) needs heat! needs heat and/or pressure! needs heat! needs catalyst!

13 Alkenes ~ C=C double bond C n H 2n (with one double bond) Geometric isomers are possible, e.g.: –Restricted C=C bond rotation –Trigonal planar geometry at C=C carbons –sp 2 hybridization at C=C carbons Nomenclature (C=C bond takes preference) cis-2-butene trans-2-butene CH 3 CH 2 CHCH 2 CH=CCH 3 CH 3 2,5-dimethyl-2-heptene cyclohexene

14 Reactions of Alkenes addition to double bond RCH=CH 2 + HX --> RXCH-CH 3 + ≡ Markovnikov’s rule ~ “them that has, gets” (H goes on the C that already has the most H’s) Addition of non-polar reagents (H 2, Br 2, etc) also occurs

15 Alkynes ~ C ≡ C Triple Bond C n H 2n-2 (with one triple bond) linear geometry at C ≡ C carbons sp hybridization at C ≡ C carbons no “cis-trans” isomers similar addition reactions to alkenes (stepwise addition can occur) XY

16 Aromatic Hydrocarbons (benzene and its derivatives) Benzene ~ C 6 H 6 planar 6-membered ring (especially stable) all C-C distances equivalent sp 2 hydridization at all carbons delocalized set of 3 double bonds (6  electrons) other common aromatic hydrocarbons: napthalene anthracenes

17 Aromatic Nomenclature Aromatic ring as substituent –Phenyl (C 6 H 5 – ) –Benzyl (C 6 H 5 CH 2 – ) Monosubstituted benzene –(name of substituent)benzene –Some common “trivial” names Toluene Phenol Polysubstituted benzene –Assign numbers to substituents 4-phenyl-1-hexene propylbenzene 1 2 3 1-bromo-3-fluorobenzene

18 Aromatic Substitution Rxns Substitution Reactions of Aromatic Hydrocarbons (never addition!) X2X2 X2X2 X = Cl, Br HNO 3 (H + catalyst) ( NOT aromatic! ) needs catalyst!

19 Organic Functional Groups FamilyCharacteristic Structural Feature Examples Hydrocarbons alkanes alkenes alkynes aromatic only single bonds C=C C ≡ C benzene ring CH 3 CH 2 =CH 2 HC ≡ CH Alcohols*R-O-HCH 3 CH 2 OH Ethers*R-O-R’CH 3 OCH 3 * structures like water

20 More Organic Functional Groups FamilyCharacteristic Structural Feature Examples Aldehydes Ketones Carboxylic Acids Esters “carbonyl” compounds

21 More Organic Functional Groups FamilyCharacteristic Structural Feature Examples Amines: 1º 2º 3º RNH 2 RNHR’ RNR’R” CH 3 NH 2 (CH 3 ) 2 NH (CH 3 ) 3 N Amides

22 Alcohols (organic derivatives of H 2 O) Nomenclature Alcohols, R-O-H R = CH 3 methanol R = CH 3 CH 2 ethanol R = CH 3 CH 2 CH 2 1-propanol (n-propanol) CH 3 CHCH 3 OH 2-propanol (iso-propanol) 3,7-dimethyl-4-octanol phenol

23 Reactions of Alcohols Oxidation primary [O] – “H 2 ” aldehyde secondary [O] – “H 2 ” ketone [O] No Reaction [O] = oxidizing agent, e.g. Cr 2 O 7 2– tertiary

24 More Reactions of Alcohols Elimination alcohol H+H+ alkene + H 2 O Substitution RCH 2 —OH + H—X – H 2 O RCH 2 —X alcohol X = Cl, Br, I alkyl halide

25 Aldehydes and Ketones Nomenclature methanal (formaldehyde) ethanal (acetaldehyde) propanal propanone (acetone) butanone (methyl ethyl ketone) 5-methyl-3-heptanone

26 Reactions of Aldehydes and Ketones Hydrogenation (reduction) of aldehydes and ketones aldehyde “H 2 ” primary alcohol ketone “H 2 ” secondary alcohol Oxidation of aldehydes (very easy!) aldehyde [O] carboxylic acid

27 Carboxylic Acids Nomenclature of Acids methanoic acid (formic acid) ethanoic acid (acetic acid) benzoic acid butanoic acid CH 3 CH 2 CH 2 CO 2 H (condensed formula) Salts of Acids acetic acid NaOH H2OH2O sodium acetate

28 Condensation Reactions a condensation reaction is any organic reaction driven by the removal of a small molecule, like water esters are made by the condensation reaction between a carboxylic acid and an alcohol the reaction is acid catalyzed acid anhydrides are made by the condensation reaction between 2 carboxylic acid molecules the reaction is driven by heat

29 Esters Nomenclature of Esters alkyl group acid name -ate ethyl acetate ethyl butanoate methyl benzoate Formation of Esters (from acid + alcohol) + +H2OH2O

30 Ethers Ethers R – O – R’ CH 3 CH 2 –O–CH 2 CH 3 diethyl ether CH 3 –O–CH 2 CH 2 CH 3 methyl propyl ether Ether Synthesis: R–O–H + H–O–R R–O–R H+H+ – H 2 O

31 Amines (organic derivatives of NH 3 ) methylaminedimethylamine methylpropylamine 2-aminohexaneaniline Like ammonia, amines are weak bases: RNH 2 + H + RNH 3 +

32 Amides Acid derivatives (e.g. 1º amides: –NH 2 instead of –OH) + + H2OH2O Nomenclature R = CH 3 R = CH 2 CH 2 CH 2 CH 3 ethanamide pentanamide, etc. amides (unlike amines) are generally not basic (due to e- withdrawing effect of the C=O group)

33 Sample Questions (1) Write complete, systematic names for:

34 Sample Questions, cont. (2) Write complete, specific structural formulas for all of the organic reactants and products in the reaction. an ester sodium acetate + 3-pentanol (3) Show, with specific structures and reactions, how the following compound can be prepared in three steps starting with the appropriate alkyne. NaOH

35 Answers 1. 2-cyano-4-methyl-3-heptene 2-butylbenzoate 4-phenylhexanal 2. NaOH + 3. + H 2 cat,  pressure step 1 + H 2 O acid cat step 2

36 Answers, cont. 3., cont. [ox]

37 Organic Polymers Polymers -- macromolecules made up of many repeating units called monomers e.g. polystyrene is formed via the polymerization of the monomer styrene: e.g. some rings can open to form polymers: h styrene polystyrene n ~ 10 3 - 10 6

38 Methods of Polymerization Addition (very common -- works with most alkenes) CH 2 =CH 2 + CH 2 =CH 2 + CH 2 =CH 2 etc…. ---CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 --- = requires an initiator (e.g. a catalyst or UV light) to start the “chain” reaction

39 More Methods of Polymerization Condensation (common for polyesters and polyamides) a small molecule (e.g. H 2 O) byproduct is formed X-A-Y + X-B-Y Ring-Opening (uncommon except for polyethers and most inorganic polymers, e.g. silicones) – XY etc…

40 Common Addition Polymers MonomerPolymer CH 2 =CH 2 —CH 2 –CH 2 — n ethylenepolyethylene CH=CH 2 styrene —CH–CH 2 — n polystyrene CH=CH 2 Cl vinyl chloride —CH–CH 2 — n n Cl poly(vinyl chloride) ~ PVC CH=CH 2 N≡CN≡C N≡CN≡C cyanoethene “Orlon”

41 One More Common Addition Polymer! Addition polymerization of dienes “isoprene” (2-methyl-1,3-butadiene) “natural” rubber

42 Common Condensation Polymers Polyesters + diacid diol polyester – H 2 O e. g. == “Dacron”

43 Sample Question Write a complete structural formula of the organic polymer that is produced in each reaction. State whether the polymerization process is addition, condensation, or ring- opening. +HO-CH 2 CH 2 -OH

44 Answer a. condensation b. ring-opening c. addition d. addition

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