Organic Chemistry. Chapter 23. Hill, Petrucci, McCreary & Perry 4 th. Ed. Alkane to Substituent Group methane CH 4 methyl CH 3

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1 hapter 23 rganic hemistry ill, Petrucci, Mcreary & Perry 4 th Ed. Alkane to Substituent Group methane 4 methyl 3 ethane 3 3 ethyl 3 2 propane propyl isopropyl ( 3 ) 2 or 3 3 butyl butane sec-butyl Alkane to Substituent Group 3 3 isobutyl 3 2 isobutane 3 3 tert-butyl or ( 3 ) 3

2 Free otation about Single Bonds n-hexane Different Views of 2-Methylpentane Distinguishing Isomers A B D E

3 arbon an ave nly Four Bonds What Is Wrong With Each of These? ycloalkanes

4 IUPA Systematic Naming of Alkanes Longest continuous carbon chain = Parent Alkane (PA) Locate any chain branching off PA, name as alkyl group. Assign smallest set of numbers to branch points counting from one end of PA. For multiple branching Locate identical alkyl groups, indicate their number using bi, di (2); tri (3); tetra (4) Locate different alkyl groups. onstruct the name by placing the alkyl groups in alphabetical order (ignoring Greek prefixes, dimethyl = m) preceded by locator number separated by hyphens from words and commas from numbers. There should be a locator number for each alkyl group, i. e. 2,2-dimethyl. 3-ethyl-2,2-dimethylpentane A nonane isomer! IUPA Systematic Naming of cycloalkanes Largest carbon ring = Parent cycloalkane (PA) use cyclo+(name of straight chain having same number of carbon atoms as the ring) Locate any chain branching off PA, name as alkyl group. For multiple branching assign consecutive numbers to ring positions that give lowest set Locate identical alkyl groups and indicate their number using bi, di (2); tri (3); tetra (4) Locate different alkyl groups. onstruct the name by placing the alkyl groups in alphabetical order (ignoring Greek prefixes, dimethyl = m) preceded by locator number separated by hyphens from words and commas from numbers. There should be a locator number for each alkyl group Methylcyclopentane 1,3-dimethylcyclopentane eactions of Alkanes Alkanes react with very few reagents, i.e. chlorine 4 + l 2 3 l + l l + 2 l 2 l 2 l 2 l 3 + l l + l 4 l 2

5 Addition eactions to the Double Bond ethene + l l chloroethane cis-2-butene 2-butanol Benzene Undergoes Addition nly Under Forcing onditions 3 2 It Mostly Undergoes Substitution l l 2 Fel 3 + l ther Substitution eactions 2 3 Br All l N 2 Br 2 N 3 FeBr 3 2 S 4 S 3

6 Naming of Benzene Derivatives Mostly ommon Names N 2 Br l F nitro-benzene bromo- chloro- fluoro- I 3 N 2 iodo- phenol toluene aniline 2 S 3 benzene sulfonic acid benzoic acid styrene benzaldehyde Simple Alcohols methyl ethyl isopropyl alcohol alcohol alcohol n-propyl alcohol methanol ethanol 2-propanol 1-propanol ommon Names: -group then alcohol IUPA Names: Parent Alkane - e + ol Diols, Triols & igher 2 2 ethylene glycol 3 2 propylene glycol butylene glycol 1,2-ethandiol 1,2-propandiol 1,2-butandiol glycerol "aldopentose" "ketohexose" 1,2,3-propantriol "sugars"

7 Properties of Alcohols Alcohols are polar, hydrogen bond with water, and each other, have higher boiling points than alkanes of similar molecular weight. Alcohols are soluble in water if the substituent group part is not too large and non-polar. 1-7 = miscible to slightly soluble, 8 and higher are insoluble. Alcohols are not acidic or basic in water, the p is not altered. eactions of Alcohols Dehydration: Note! Two carbon atoms involved! minor major major product minor product When two alkenes are possible: More highly branched is favored. xidation of Primary Alcohols [] = oxidizing agent 3 ethanol [] ethanal (acetaldehyde) Aldehydes are formed! 3 2 propanol [] propanal (propionaldehyde)

8 xidation of Secondary Alcohols [] = oxidizing agent [] propanol propanone (acetone) Ketones are formed! butanol [] butanone (methyl ethyl ketone) Further xidation of Primary Alcohols Aldehydes are formed first but oxidize easily to carboxylic acids: [] 3 3 ethanal (acetaldehyde) from ethanol [] 3 2 propanal (propionaldehyde) ethanoic (acetic) acid 3 2 propanoic (propionic) acid Ketones and tertiary alcohols resist further oxidation. Important Unsaturated xygen Functions found in carbonyl aldehydes ketones carboxyl found in carboxylic acids esters

9 ETES Ethers have two non-carbonyl hydrocarbon groups bonded to oxygen. Ethers are nearly as unreactive as the alkanes. Ethers are as volatile as alkanes of similar molecular weight. They cannot donate a hydrogen bond to each other. Ethers are polar and can accept a hydrogen bond from water; they are about as soluble in water as isomeric alcohols. Synthesis of Ethers from Alcohols & Phenols S 4 3 Ethyl alcohol = Ethanol (di)ethyl Ether + acid catalyst Phenol Phenol (di)phenyl Ether acid catalyst 2 3 Phenol Ethanol Ethyl Phenyl Ether arboxylic Acids & Esters - carboxylate group is planar its anion is also planar

10 arboxylic Acids, - arboxylic acids have a hydroxy group bonded to the carbonyl group. The group is polar like aldehydes and ketones but like alcohols it can donate a hydrogen bond to itself. The carboxylic acids are much higher boiling ( less volatile ) than even the alcohols of similar molecular weight. Lower carboxylic acids have very pungent and irritating odors. They are unsaturated undergo addition reactions with polar molecules forming acid derivatives not true addition compounds. carboxylate group dimerizes easily arboxylic Acids ommon/iupa Names formic acid acetic acid propionic acid butyric acid methanoic acid ethanoic acid propanoic acid butanoic acid benzoic acid phenylmethanoic acid Esters - () Esters have an alkyl group bonded to the carboxylate group. The group is polar but unlike carboxylic acids it cannot donate a hydrogen bond to itself. Esters are more volatile (lower boiling) than carboxylic acids and are somewhat less soluble in water than carboxylic acids of similar molecular weight. Esters have pleasant, fruity odors and most are nontoxic. They are also unsaturated and undergo many reactions with polar molecules. ester group is planar

11 Naming Esters ommon & IUPA ommon Name IUPA Name methyl acetate 3 3 methyl ethanoate methyl propionate methyl propanoate ethyl propionate ethyl propanoate methyl butyrate methyl butanoate phenyl acetate 3 phenyl ethanoate. Synthesis of Esters & Acyl Transfer Agents direct esterification: 3 transfer reactions: alcohol group alcohol group acid chloride 3 l alcohol group acid anhydride alcohol group 100% 100% alcohol group alcohol group Saponification (Breakdown) of Esters saponification: alcohol group alcohol group. reverse of direct esterification: alcohol group alcohol group

12 Properties of Amides Amides are polar, hydrogen bond with water, and each other when the nitrogen bears a hydrogen atom. Amides have much higher melting and boiling points than alcohols or amines of similar molecular weight, are also soluble in water if the substituent group part is not too large and non-polar. Amides do NT affect the p of a water solution. The amide linkage can be hydrolysed in strong acid solution back to the carboxylic acid and the salt of the amine from which it was synthesized 3 2 acyl part amide linkage amine part N 3 3 Synthesis of Amides with Acyl Transfer Agents transfer reactions: 3 l acid chloride acid anhydride N 2 3 amine group 3 N 2 3 amine group 100% 100% 3 3 N 2 3 amine group 3 + l 3 N 2 3 amine group + 3 arboxylic Acids & Amines Give Salts A carboxylic acid & amine react as acid & base: N % N 2 3 amine group amine group The transfer reaction does not occur.

13 Acids & Bases ydrolyze Amides Acid Promoted ydrolysis (Breakdown) of Amides l strong acid 3 2 N l carboxylic acid N 3 3 ammonium salt water 3 Base Promoted ydrolysis (Breakdown) of Amides 3 2 N Na carboxylate anion Na 3 N 3 amine sodium hydroxide 3