Handout: Naming Organic Compounds A. IUPAC Naming General Rules: Some Substituent Names Prefix + Parent + Suffix Substituent Substituent Name Specific Examples Family Group Substituents Hydrocarbon alkyl H2 H C H C C Longest carbon chain with single 3 3 bonds only methyl ethyl CH 3 CH3 H2 1. Name parent+suffix: longest carbon chain + family suffix. H3C C H3C C C 2. Number carbons in parent chain: Begin numbering from end H H that meets specified criteria (*See Nomenclature Chart). isopropyl isobutyl 3. Name prefix: substituent position #s and names (grouping H2 H3C C C CH3 repeated substituents together using di-, tri-, etc). H sec-butyl 4. Write full name, listing substituents in alphabetical order CH3 (ignoring di-, tetra- in alphabetizing). H3C C CH3 tert-butyl Name Format: #–substituent–#–substituentparentsuffix O O acyl O C C C R (Ends with –oyl, H3C C H3C H2 except for acetyl) acetyl propanoyl Some Parent Alkane Names –OR alkoxy H2 H C C No. of Structure Name H3C 3 Carbons methoxy ethoxy O 1 CH4 Methane formyl 2 CH3CH3 Ethane HC 3 CH3CH2CH3 Propane O keto 4 CH3 CH2CH2CH3 Butane C 5 CH3 CH2CH2CH2CH3 Pentane –OH hydroxy 6 CH3 CH2CH2CH2CH2CH3 Hexane -NO2 nitro 7 CH3CH2CH2CH2CH2CH2CH3 Heptane –NH2 amino 8 CH3CH2CH2CH2CH2CH2CH2CH3 Octane -X (halogen) halo -Cl chloro -Br bromo 9 CH3CH2CH2CH2CH2CH2CH2CH2CH3 Nonane -I iodo 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 Decane phenyl H. Kim for Chem 30B 1 B. Common Names Some Widely-Used Common Names Compound Common Name IUPAC Name CH2=CH2 ethylene 1-ethene CH3CH=CH2 propylene 1-propene HC CH acetylene 1-ethyne O acetone 2-propanone C CH3 H3C O formaldehyde methanal CH2 O acetaldehyde ethanal CH H3C O formic acid methanoic acid HC OH O acetic acid ethanoic acid C H3C OH O propionic acid propanoic acid C H3C C OH H2 O butyric acid butanoic acid H2 C H3C C C OH H2 H. Kim for Chem 30B 2 Nomenclature Chart for Organic Compounds (From HIGHEST TO LOWEST naming priority) FAMILY PARENT SUFFIX NUMBERING NOTES EXAMPLES Carboxylic acid Parent is longest –oic acid Begin at carbonyl C. Common names are often used O carbon chain (C next to COOH group is H H C C C OH containing carboxylic (-dioic acid designated as “α”). 3 acid. Derive name for dicarbox- Cl from parent alkane. ylic acid; [Salts: cation + name derived 2-chloropropanoic acid or -enoic acid from parent acid, replacing –ic α-chloropropionic acid (common) for unsatur- acid with –ate ] ated acid) Ester Name of alkyl group –ate Begin at carbonyl C. Common names are often used: O that replaced -H in name of alkyl group that H2 H2 H2 H3C C C C O C CH3 -COOH + name replaced -H in -COOH + name ethyl butanoate or derived from parent derived from common name of ethyl butyrate (common) acid, replacing –ic acid parent acid, replacing –ic acid with –ate with –ate Amides Derive name from –amide Begin at carbonyl C. Alkyl substituents on nitrogen O CH3 parent carboxylic acid, start with “N-.” H C C N CH replacing –oic acid 3 3 with –amide. N,N-dimethylacetamide Aldehydes Derive name from –al Begin at carbonyl C. Common names are often used CH3 O parent alkane. for simplest aldehydes, ending H2 H3C C C C H with “–aldehyde.” H 3-methylbutanal or β-methylbutyraldehyde (common) Ketones Derive name from –one Begin at end nearer Common names are often used O parent alkane. Parent to carbonyl C. for simple ketones: names of H2 H2 H3C C C C CH3 name starts with two alkyl groups + “ketone.” 2-pentanone or position # of carbonyl methyl propyl ketone (common) C. Alcohol Parent is longest –ol Begin at end nearer Cyclic alcohols: Parent name CH3 OH carbon chain to OH group. begins with “cyclo” (no need to H2 H2 H3C C C C C CH3 containing OH. Parent (-diol, start parent name with “1”). H H name starts with -triol, etc.) Begin numbering at C with OH, 5-methyl-3-hexanol position # of the C and number to give OH with OH. substituents lowest numbers. CH3 2-methylcyclohexanol OH H2 H2 H3C C C C OH H 1,3-butanediol Thiols –thiol Name in same way as alcohols, H2 H C C SH except end with “-thiol.” 3 ethanethiol H. Kim for Chem 30B 3 FAMILY PARENT SUFFIX NUMBERING NOTES EXAMPLES Amines –amine 1° amines, and 2°, 3° amines H2 H2 with same R groups on N: Treat H3C C C NH2 (1°) alkyl groups attached to propylamine nitrogen as substituents. For same substituents, use “di” and H2 H2 H3C C N C CH3 (3° with same R “tri.” groups) 2°, 3° amines with different R H2C CH3 groups on N: Parent amine is triethylamine the one with largest R group; name other groups as H2 H2 H substituents, starting with N-. H3C C C N CH3 (2° with [Ions derived from amines: diff’t R groups) Replace –amine with N-methylpropanamine –ammonium.] Alkenes Parent is longest –ene Begin at end closer Cyclic alkenes: Parent name H2 H3C C CH2CH2CH3 Alkynes carbon chain –yne to multiple bond. begins with “cyclo” (no need to C C containing the double (If multiple bonds start parent name with “1”). H CH3 or triple bond. Parent (-diene, are equidistant, Number multiple bonds 1 and cis-4-methyl-3-heptene name starts with -triene, etc.) give smaller 2, in direction to give first position number of number to first substituent the next smaller H2 H2 H2 multiple bond. branch point). possible number. H3C C C C C C CH3 May need cis/trans Then give smallest 2-heptyne designation. numbers possible CH3 to substituents. 4-methylcyclohexene Alkanes Parent is longest –ane Begin at end nearer Cyclic alkanes: Parent name CH3 carbon chain. to branch point. begins with “cyclo.” Give H2 H H2 H3C C C C C CH3 Then give smallest smallest number to substituent H numbers possible that comes first in alphabetical H2C CH3 to substituents. order. Number in direction to 4-ethyl-2-methylhexane give second substituent the H2 H C C CH smaller possible number. (If 3 3 single substituent, don’t need “1-.”) 1-ethyl-3-methylcyclohexane Ethers The alkoxy group –OR Common names are often used H2 H2 H2 H C C O C C CH is treated as the for simple ethers: two R groups 3 3 substituent (Alkane or + “ether.” 1-ethoxypropane or another functional Common names are used for ethyl propyl ether (common) group is the parent). cyclic ether compounds. H2 H2 H2 H2 H3C C O C C C OH 3-ethoxypropanol H. Kim for Chem 30B 4 Haloalkanes (or Halogen atom is Common names are often used, H2 Alkyl Halides) treated as substituent in format “alkyl halide.” H3C C Br (Alkane or another 1-bromoethane or functional group is the ethyl bromide (common) parent). Aromatic Nomenclature (*Functional group priority is same in aromatic and aliphatic nomenclature.) FAMILY PARENT SUFFIX NUMBERING NOTES EXAMPLES Benzene “benzene” or common For di-substituted Common names for substituted name for substituted benzenes, o, m, p benzenes are often used NO2 benzene typically used for (accepted by IUPAC): positions of CH3 OH substituents. Cl m-chloronitrobenzene Toluene Phenol o- OH O O CH C OH O2N m- p-nitrophenol Benzaldehyde Benzoic acid NH2 p- Aniline H. Kim for Chem 30B 5 .