John E. McMurry Paul D. Adams University of Arkansas Chem 2412 Additional Nomenclature

 Starting materials for acyl derivatives (esters, amides, and acid chlorides)  Abundant in nature from oxidation of aldehydes and alcohols in metabolism  Acetic acid, CH 3 CO 2 H, - vinegar  Butanoic acid, CH 3 CH 2 CH 2 CO 2 H (rancid butter)  Long-chain aliphatic acids from the breakdown of fats The Importance of Carboxylic Acids (RCO 2 H)

1. Carboxylic Acids (3 O bonds, 1 OH) 2. Esters (3 O bonds, 1 OR) 3. Amides 4. Nitriles 5. Aldehydes (2 O bonds, 1H) 6. Ketones (2 O bonds) 7. Alcohols (1 O bond, 1 OH) 8. Thiols 9. Amines 10. Alkenes, Alkynes 11. Alkanes 12. Ethers 13. Halides The parent will be determined based on the highest priority functional group. Functional Group Priority

 Carboxylic Acids, RCO 2 H  If derived from open-chain alkanes, replace the terminal - e of the alkane name with -oic acid  The carboxyl carbon atom is C Naming Carboxylic Acids and Nitriles

 Compounds with –CO 2 H bonded to a ring are named using the suffix -carboxylic acid  The CO 2 H carbon is not itself numbered in this system  Use common names for formic acid (HCOOH) and acetic acid (CH 3 COOH) – see Table 20.1 Alternative Names

 Closely related to carboxylic acids named by adding - nitrile as a suffix to the alkane name, with the nitrile carbon numbered C1  Complex nitriles are acids; named as derivatives of carboxylic acids.  Replace -ic acid or -oic acid ending with -onitrile Nitriles, RCN

 Carboxyl carbon sp 2 hybridized: carboxylic acid groups are planar with C–C=O and O=C–O bond angles of approximately 120°  Carboxylic acids form hydrogen bonds, existing as cyclic dimers held together by two hydrogen bonds  Strong hydrogen bonding causes much higher boiling points than the corresponding alcohols 20.2 Structure and Properties of Carboxylic Acids

 Carboxylic acids are proton donors toward weak and strong bases, producing metal carboxylate salts, RCO 2  + M  Carboxylic acids with more than six carbons are only slightly soluble in water, but their conjugate base salts are water-soluble Dissociation of Carboxylic Acids

 Carboxylic acids transfer a proton to water to give H 3 O + and carboxylate anions, RCO 2 , but H 3 O + is a much stronger acid  The acidity constant, K a,, is about for a typical carboxylic acid (pK a ~ 5) Acidity Constant and pK a

 Electronegative substituents promote formation of the carboxylate ion Substituent Effects on Acidity

 Fluoroacetic, chloroacetic, bromoacetic, and iodoacetic acids are stronger acids than acetic acid  Multiple electronegative substituents have synergistic effects on acidity Inductive Effects on Acidity

 Acyl group bonded to X, an electronegative atom or leaving group  Includes: X = halide (acid halides), acyloxy (anhydrides), alkoxy (esters), amine (amides), thiolate (thioesters), phosphate (acyl phosphates) Carboxylic Compounds

 Nucleophilic acyl substitution Why this Chapter?  Carboxylic acids are among the most widespread of molecules.  A study of them and their primary reaction “nucleophilic acyl substitution” is fundamental to understanding organic chemistry General Reaction Pattern

 Acid Halides, RCOX  Derived from the carboxylic acid name by replacing the -ic acid ending with -yl or the -carboxylic acid ending with – carbonyl and specifying the halide 21.1 Naming Carboxylic Acid Derivatives

 If symmetrical replace “acid” with “anhydride” based on the related carboxylic acid  Unsymmetrical anhydrides— cite the two acids alphabetically Naming Acid Anhydrides, RCO 2 COR'

 With unsubstituted  NH 2 group. replace -oic acid or -ic acid with -amide, or by replacing the -carboxylic acid ending with –carboxamide  If the N is further substituted, identify the substituent groups (preceded by “N”) and then the parent amide Naming Amides, RCONH 2

Naming Amides N,N-dimethylethanamideN-isobutylmethylbutanamide N-ethyl-N- phenylbenzamide N,2-dimethylbenzamide

 Name R’ and then, after a space, the carboxylic acid (RCOOH), with the “-ic acid” ending replaced by “-ate” Naming Esters, RCO 2 R’

Naming Esters  Esters may have common or IUPAC names  The first word of the name of an ester is the name of alkyl or aromatic group (R)  Change the –ic acid ending of the acid name to –ate (like naming carboxylic acid salts)  Parent contains the –COO group methyl ethanoate phenyl butanoateethyl benzoate isopropyl methanoate methyl benzoate

 For simple amines, the suffix -amine is added to the name of the alkyl substituent IUPAC Names – Simple Amines

IUPAC Names – “-amine” Suffix  Replace –e in alkane with –amine.  Number position of amino group lowest on parent chain.  If substituent on nitrogen, prefixed with N. 3-Pentanamine3-Methyl-1-butanamine N-Methyl-2-butanamine 2-Hexanamine N-Methyl-2-hexanamine N,N-Dimethyl-2-hexanamine N-Ethyl-N-methyl-2-hexanamine 2,5-hexanediaminecyclohexylamine

 Consider the –NH 2 as an amino substituent on the parent molecule IUPAC Names – Amines with More Than One Functional Group

 Symmetrical secondary and tertiary amines are named by adding the prefix di- or tri- to the alkyl group IUPAC Names – Multiple Alkyl Groups

 Named as N-substituted primary amines  Largest alkyl group is the parent name, and other alkyl groups are considered N-substituents IUPAC Names – Multiple, Different Alkyl Groups

 If the nitrogen atom occurs as part of a ring, the compound is designated as being heterocyclic  Each ring system has its own parent name Common Names of Heterocyclic Amines

 Many common names (toluene = methylbenzene; aniline = aminobenzene)  Monosubstituted benzenes systematic names as hydrocarbons with –benzene  C 6 H 5 Br = bromobenzene  C 6 H 5 NO 2 = nitrobenzene, and C 6 H 5 CH 2 CH 2 CH 3 is propylbenzene 15.1 Naming Aromatic Compounds

 6 C ring structures with alternating double bonds (benzene).  Everything that is not aromatic, is aliphatic (alkanes, alkenes, alkynes).  Early problem chemists found was that benzene was not reactive (recall that alkenes are reactive due to double bond).  Kekule proposed that double bonds alternated between 2 equivalent structures  electrons move around a conjugated pi bond system of rings  Stabilizes structure and makes it less reactive. Aromatics

1. For single replacement (H  some FG), cmpd named as a benzene derivative. Naming Benzene Derivatives

Some common names are IUPAC-accepted and used preferentially. Naming Benzene Derivatives (Continued)

 With only 2 groups on benzene ring, can use o, m, p (ortho, meta, para) nomenclature. Naming Benzene Derivatives (Continued)

 Choose numbers to get lowest possible values  List substituents alphabetically with hyphenated numbers  Common names, such as “toluene” can serve as root name (as in TNT) Naming Benzenes with More Than Two Substituents

 When a benzene ring is a substituent, the term phenyl is used (for C 6 H 5 ? )  You may also see “Ph” or “  ” in place of “C 6 H 5 ”  “Benzyl” refers to “C 6 H 5 CH 2 ?” The Phenyl Group

The benzene ring can also be an attached substituent group. Benzene as a Phenyl group