Ch 3 Review Nomenclature Organic Compounds Compounds of

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Ch. 3 Review: Nomenclature: Organic Compounds • Compounds of carbon--organic chemistry – If they

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: Cn. H 2 n+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.

Organic chemistry -- Chapter 20 • Introductory Topics Bonding & Structure -- Review Chapters

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

Isomerism • Isomers– different molecules with the same molecular formula Structural isomers--different pattern of

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!!

Structural Isomers • Structural Isomers -- same chemical formula, but different arrangement (connectivity) of

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) 1 -propanol 2 -propanol ethyl methyl ether Number of possible isomers can be very large, e. g. C 3 H 8 C 4 H 10 C 5 H 12 C 6 H 14 C 8 H 18 1 2 3 5 18 C 10 H 22 C 20 H 42 75 > 105

Stereoisomers • Stereoisomers—same atom attachments (connectivity), different spatial orientation • Optical isomers (enantiomers)—are molecules

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

Chiral Molecules • Are molecules that have nonsuperimposable mirror images – If 4 different

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

Isomerism; Overview 7

Isomerism; Overview 7

Many Possible Compounds A Tremendous Variety of organic molecular structures and properties are possible,

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

More Organic Compounds Caffeine C 8 H 10 N 4 O 2 methylamine fortunately,

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”

Hydrocarbons • Alkanes Cn. H 2 n+2 CH 4 methane C 2 H 6

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

Alkane Nomenclature 1. 2. Name parent chain--longest continuous chain Number parent chain -- First

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

Reactions of Alkanes (generally unreactive) • Combustion -- fuels! e. g. C 5 H

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) at! he s d e e n ssu e r p r o t and/ a he s d e e n t! lys a t a c ds nee t! hea s d e ne re!

Alkenes ~ C=C double bond Cn. H 2 n (with one double bond) •

Alkenes ~ C=C double bond Cn. H 2 n (with one double bond) • Geometric isomers are possible, e. g. : cis-2 -butene trans-2 -butene – 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) CH 3 CH 2 CH=CCH 3 2, 5 -dimethyl-2 -heptene cyclohexene

Reactions of Alkenes addition to double bond RCH=CH 2 + HX --> RXCH-CH 3

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

Alkynes ~ C≡C Triple Bond Cn. H 2 n-2 (with one triple bond) •

Alkynes ~ C≡C Triple Bond Cn. H 2 n-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 XY

Aromatic Hydrocarbons (benzene and its derivatives) Benzene ~ C 6 H 6 • •

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 p electrons) other common aromatic hydrocarbons: napthalene anthracenes

Aromatic Nomenclature • Aromatic ring as substituent – Phenyl (C 6 H 5–) –

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 3 2 1 1 -bromo-3 -fluorobenzene

Aromatic Substitution Rxns • Substitution Reactions of Aromatic Hydrocarbons (never addition!) X 2 X

Aromatic Substitution Rxns • Substitution Reactions of Aromatic Hydrocarbons (never addition!) X 2 X = Cl, Br X 2 HNO 3 (H+ catalyst) ( NOT aromatic! ) st! ne taly a c s ed

Organic Functional Groups Family Hydrocarbons alkanes alkenes alkynes aromatic Characteristic Structural Feature Examples only

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

More Organic Functional Groups “carbonyl” compounds Family Aldehydes Ketones Carboxylic Acids Esters Characteristic Structural

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

More Organic Functional Groups Family Characteristic Structural Feature Examples Amines: 1º 2º 3º RNH

More Organic Functional Groups Family Characteristic 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

Alcohols (organic derivatives of H 2 O) Nomenclature Alcohols, R-O-H R = CH 3

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

Reactions of Alcohols Oxidation [O] primary – “H 2” aldehyde [O] secondary – “H

Reactions of Alcohols Oxidation [O] primary – “H 2” aldehyde [O] secondary – “H 2” [O] ketone No Reaction tertiary [O] = oxidizing agent, e. g. Cr 2 O 72–

More Reactions of Alcohols Elimination + H 2 O H+ alkene alcohol Substitution RCH

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

Aldehydes and Ketones Nomenclature methanal (formaldehyde) propanone (acetone) ethanal (acetaldehyde) butanone (methyl ketone) propanal

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

Reactions of Aldehydes and Ketones Hydrogenation (reduction) of aldehydes and ketones “H 2” primary

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

Carboxylic Acids Nomenclature of Acids methanoic acid (formic acid) ethanoic acid (acetic acid) benzoic

Carboxylic Acids Nomenclature of Acids methanoic acid (formic acid) ethanoic acid (acetic acid) benzoic acid CH 3 CH 2 CO 2 H (condensed formula) butanoic acid Salts of Acids Na. OH H 2 O acetic acid sodium acetate

Condensation Reactions • a condensation reaction is any organic reaction driven by the removal

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 an alcohol ü the reaction is acid catalyzed • acid anhydrides are made by the condensation reaction between 2 carboxylic acid molecules ü the reaction is driven by heat

Esters Nomenclature of Esters alkyl group acid name ethyl acetate -ate ethyl butanoate methyl

Esters Nomenclature of Esters alkyl group acid name ethyl acetate -ate ethyl butanoate methyl benzoate Formation of Esters (from acid + alcohol) + + H 2 O

Ethers R – O – R’ CH 3 CH 2–O–CH 2 CH 3 diethyl

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

Amines (organic derivatives of NH 3) methylamine methylpropylamine dimethylamine 2 -aminohexane aniline Like ammonia,

Amines (organic derivatives of NH 3) methylamine methylpropylamine dimethylamine 2 -aminohexane aniline Like ammonia, amines are weak bases: RNH 2 + H+ RNH 3+

Amides Acid derivatives (e. g. 1º amides: –NH 2 instead of –OH) + +

Amides Acid derivatives (e. g. 1º amides: –NH 2 instead of –OH) + + Nomenclature R = CH 3 R = 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) H 2 O

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

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

Sample Questions, cont. (2) Write complete, specific structural formulas for all of the organic

Sample Questions, cont. (2) Write complete, specific structural formulas for all of the organic reactants and products in the reaction. an ester Na. OH 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.

Answers 1. 2 -cyano-4 -methyl-3 -heptene 2 -butylbenzoate 4 -phenylhexanal 2. Na. OH +

Answers 1. 2 -cyano-4 -methyl-3 -heptene 2 -butylbenzoate 4 -phenylhexanal 2. Na. OH + cat, D 3. + H 2 O pressure acid cat step 1 step 2

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

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

Organic Polymers -- macromolecules made up of many repeating units called monomers e. g.

Organic Polymers -- macromolecules made up of many repeating units called monomers e. g. polystyrene is formed via the polymerization of the monomer styrene: hn n ~ 103 - 106 styrene e. g. some rings can open to form polymers: polystyrene

Methods of Polymerization Addition (very common -- works with most alkenes) CH 2=CH 2

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

More Methods of Polymerization Condensation (common for polyesters and polyamides) a small molecule (e.

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 – XY Ring-Opening (uncommon except for polyethers and most inorganic polymers, e. g. silicones) etc…

Common Addition Polymers Monomer CH 2=CH 2 Polymer —CH 2–CH 2—n ethylene polyethylene CH=CH

Common Addition Polymers Monomer CH 2=CH 2 Polymer —CH 2–CH 2—n ethylene polyethylene CH=CH 2 —CH–CH 2— n styrene CH=CH 2 Cl vinyl chloride CH=CH 2 N≡C cyanoethene polystyrene —CH–CH 2— Cl n poly(vinyl chloride) ~ PVC —CH–CH 2— N≡C n “Orlon”

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

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

Common Condensation Polymers Polyesters + diacid diol – H 2 O polyester e. g.

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

Sample Question Write a complete structural formula of the organic polymer that is produced

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 -OH

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

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