Organic Nomenclature PDF

A. Halogen and Nitro- Substituted Aromatics 24 NOMENCLATURE IN ORGANIC CHEMISTRY B. Carboxylic Acids and Derivatives 24 C. Phenols and Thiophenols...

A. Halogen and Nitro- Substituted Aromatics 24 NOMENCLATURE IN ORGANIC CHEMISTRY B. Carboxylic Acids and Derivatives 24 C. Phenols and Thiophenols 25 Contents D. Aldehydes and Ketones 26 1. INTRODUCTION 3 E. Sulfonic acids and Sulfonic Acid Derivatives 27 2. HYDROCARBONS 3 F. Aromatic Amines 28 (i) Alkanes 3 G. Diazonium Salts 29 A. Unbranched Chains 3 6. RADICOFUNCTIONAL NAMING 29 B. Unbranched chains 4 A. Alkyl Halides 29 (ii) Alkenes 5 B. Alcohols 29 A. One double bond 5 C. Ketones 30 B. More than one double bond 5 D. Nitriles (or Cyanides) 30 C. E/Z Isomers in Alkenes 6 E. Grignard Reagents 30 (iii) Alkynes 8 (iv) Combined Alkenes and Alkynes 8 (v) Cyclic Hydrocarbons 9 3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS 10 4. COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES 12 (i) General Naming Scheme 12 A. Choosing the Principal Chain 13 B. Naming the Principal Chain 13 C. Numbering the Principal Chain 13 (ii) Naming Various Classes of Organic Compounds 14 A. Ethers and Thioethers 14 B. Alcohols and Thiols 14 C. Acids, Salts of Acids and Acid Anhydrides 15 D. Esters 17 E. Acid Halides 18 F. Amides 18 G. Nitriles 19 H. Aldehydes 19 I. Ketones 21 J. Amines and Ammonium Salts 22 Revised and updated 5. AROMATIC COMPOUNDS 23 Professor L D Field (i) General Notes 23 May 2004 (ii) Aromatic Hydrocarbons 23 (iii) Substituted Aromatic Hydrocarbons 24 1 2  B. Branched Chains NOMENCLATURE IN ORGANIC CHEMISTRY The following steps are taken in naming an alkane with a branched chain: (a) Find the longest continuous carbon chain and select the appropriate alkane name 1. INTRODUCTION from Table 1. (Side chains are not included in the carbon count.) It is important that organic compounds are corrrectly and unambiguously named so that there (b) Name all of the side chains (carbon chains attached to the longest chain) and list can be absolutely no confusion about what compounds are actually being reported or them in alphabetical order. Ignore multiplicative prefixes such as “di-“ (2), “tri-“ described. There have been many conventions for naming organic compounds - some have (3), "tetra-" (4) etc. Also ignore "sec-" and "tert-" but not "iso". had limit scope or become embedded in common usage and some have persisted over time (c) Number the longest chain so that substituents have the lowest possible numbers The International Union of Pure and Applied Chemistry (I.U.P.A.C.) periodically reviews and insert location numbers before each of the side chain names. naming practice, attempting to standardise nomenclature. The following guidelines for organic nomenclature are based on the definitive rules published by I.U.P.A.C.1 (the Special Note: The following groups have the special names indicated: International Union of Pure and Applied Chemistry). CH 3 CH3 2. HYDROCARBONS isopropyl isobutyl CH CH CH2 (i) The Alkanes (CnH2n+2) CH3 CH3 A. Unbranched Chains The first four (n=1-4) unbranched chain saturated hydrocarbons are called methane, ethane, CH 3 secondary-butyl CH3 tertiary-butyl propane and butane. After this, there is a numerical term (of Greek origin) followed by the sec-butyl tert-butyl ending "-ane". The first twelve members are given in Table 1. CH CH3 C s-butyl t-butyl Table 1. The names of the first 12 linear alkanes CH 3 CH3 n Name Molecular formula Constitutional formula CH3 1 methane CH4 CH4 2 ethane C2H6 CH3CH3 3 propane C3H8 CH3CH2CH3 Examples 4 butane C4H10 CH3CH2CH2CH3 CH3 CH2 CH CH2 CH3 3-methylpentane 5 pentane C5H12 CH3CH2CH2CH2CH3 CH3 6 hexane C6H14 CH3CH2CH2CH2CH2CH3 CH3 CH CH2 CH CH CH2 CH3 2,4,5-trimethylheptane 7 heptane C7H16 CH3CH2CH2CH2CH2CH2CH3 (not 3,4,6-) 8 octane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 CH3 CH3 CH3 9 nonane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3 CH3 10 decane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 4-isopropyl-2,2-dimethylheptane CH3 CH2 CH2 CH CH2 CH CH3 11 undecane C11H24 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 CH CH3 12 dodecane C12H26 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 CH3 CH3 CH3 CH2 4-ethyl-5-methyloctane The group derived from one of these alkanes by removal of a terminal (end) hydrogen is (not 5-ethyl-4-methyloctane) called an alkyl group. The group name is found by removing "ane" from the alkane name CH3 CH2 CH2 CH CH CH2 CH2 CH3 and adding "yl". CH3 Example: CH3-CH2-CH2-CH3 butane becomes CH3-CH2-CH2-CH2- butyl Note: The free valence must be on the terminal carbon. 1 I.U.P.A.C. Nomenclature for Organic Chemistry, Sections A, B and C (combined edition), Butterworths Scientific Publications, London, 1971. 3 4 The following compounds have special names: CH3 CH CH2 propene CH3 CH CH3 CH3 CH CH CH3 2-butene CH3 isobutane CH3 CH3 CH CH2CH3 CH3 C CH CH 4,4-dimethyl-2-pentene isopentane CH3 CH3 CH3 CH3 neopentane Special Note CH3 C CH3 CH2 CH2 has the special name “ethylene”. CH3 B. More than one double bond Branched side chains are named by renumbering the alkyl group giving the carbon with the (a) Find and name the longest carbon chain containing the maximum number of free valence (i.e. point of attachment to the main chain) the number 1 and giving substituents double bonds. the appropriate number in the usual way. (b) Change the "ane" of the alkane name to: Examples "adiene" 2 double bonds CH3CH2 CH CH2 "atriene" 3 double bonds CH3 2-methylbutyl group "atetraene" 4 double bonds etc. (c) Number the chain so as to give the double bonds the lowest possible numbers. CH3 CH CH CH2 CH CH3 1,3,4-trimethylpentyl group (d) Name the alkyl side chains in the usual way. CH3 CH3 Examples (note position of numbers and punctuation) The following example gives the name of an alkane having a branched side chain: CH2 CH CH CH2 1,3-butadiene CH3 CH3 CH CH C CH CH CH2 CH2 CH CH2 CH3 4-butyl-2-methyl-1,3,5-heptatriene CH3 CH2 CH2 CH2 CH3 CH3 CH2 CH2 CH CH2 CH CH2 CH2 CH2 CH2 CH3 CH2 CH3 Special Note 4-ethyl-6-(2-methylbutyl)undecane has the special name “allene”. CH2 C CH2 (ii) The Alkenes (CnH2n) A. One double bond C. E/Z Isomers in Alkenes (a) Find and name the longest carbon chain containing the double bond. In the past, the terms cis and trans have been used to differentiate the isomers; cis to indicate the isomer in which the substituents are on the same side of the double bond, trans (b) Change the “ane" of the alkane name to “ene". when they are on opposite sides. This nomenclature is still used in some older texts, (c) Number the carbon chain giving the double bond the lowest possible location however, the approved nomenclature for alkene stereoisomers involves the prefixes Z- or E-. number. There are two substituents attached to each of the carbon atoms which form a C=C. The (d) Name side chains in the usual way. carbon atoms at either end of the C=C are considered separately and at each end, the two attached substituents are ranked according to a simple set of priority rules (or sequence rules). The priority of the two groups attached to each carbon atom of the C=C is based Examples (note position of numbers and punctuation) initially on the atomic number of the atom at the point of attachment. For example, a chlorine 5 6 substituent would have a higher priority than a CH3- which in turn would have a higher priority CH3 CH3 E-3-methyl-2-pentene than a H-. C C (note that –CH2CH3 has greater priority than – CH3) When the C=C is considered as a whole, if the groups with the highest priorities are on the H CH2CH3 same side of the double bond then the name of the alkene is prefixed with a Z (from the German 'zusammen' meaning 'together'). If they are on opposite sides then the prefix is E Cl CH3 E-3-chloro-2-methyl-2-penten-1-ol (from 'entgegen' meaning 'opposite'). C C (note that –Cl has higher priority than –CH3 and high priority high priority high priority low priority CH3 CH2OH -CH2OH has higher priority than -CH3) A X A X priority A > B C C priority X > Y priority A > B C C priority X < Y B Y B Y (iii) The Alkynes (CnH2n-2) low priority low priority low priority high priority These are named in identical fashion to alkenes except that "ene" in the alkene name is replaced by: Z- alkene E- alkene "yne" 1 triple bond Priority Rules "adiyne" 2 triple bonds Each of the atoms attached directly to the C atom of a C=C is assigned a priority based on its "atriyne" 3 triple bonds etc. atomic number: the higher the atomic number, the higher the priority. In terms of priority, if Example (note position of numbers and punctuation) there is a hydrogen attached to one carbon of the C=C, it must always have the lowest priority. Groups which have an oxygen atom attached directly to the C=C (eg. -OH, -OCH3) CH3 C C CH2 CH3 2-pentyne have higher priority than groups which have a nitrogen atom attached directly to the C=C atom (eg. –NH2, -N(CH3)2) and so on. Special Note -I > -Br > -Cl > -OH > -NH2 > -CH3 > -H H C C H has the special name “acetylene”. If two of the groups attached to the same carbon of a C=C begin with the same element (eg. –CH3, -CH2CH3), then look to the next atoms away from the C=C. If the groups at this Salts of Alkynes point are still the same, then move further from the C=C until the point of difference is found The salts of hydrocarbon anions are named by adding the ending "-ide" together with a (there must be a point of difference somewhere). The group priority is then assigned based location number. on the atomic numbers of the atoms at the point of difference. Examples So for example –CH2Cl has a higher priority than –CH2OH. C - + lithium 1-propyn-1-ide (from propyne) -CH2Br > -CH2Cl > -CH(CH3)2 > -CH2CH3 > -CH3 CH3 C Li For the purposes of assigning group priorities, double bonds or multiple bonds are expanded to be an equivalent number of atoms attached by single bonds. So a -CH=CH2 group is H3C C - + sodium 1-butyn-1-ide (from 1-butyne) CH2 C Na considered as equivalent to -CH(-CH2)2. Examples Special Note: CH3 CH3 - + + -C - + are called monosoium acetylide and H C C Na Na C Na disodium acetylide respectively C C Z-2-butene H H (iv) Combined Alkenes and Alkynes H CH3 C C E-2-butene If a compound has double and triple bonds then the longest chain is selected so as to contain the maximum number of double and triple bonds and is named by replacing the CH3 H "ane" of the corresponding alkane by "en(e)", "adien(e)" etc. followed by "yne", "diyne" etc. Z-2-chloro-2-butene The "e" is omitted before a vowel or a "y". Cl CH3 C C (note –Cl has higher priority than -CH3) The chain is numbered so as to give the lowest numbers to the double bonds, then triple bonds. CH3 H 7 8 Examples (note positions of numbers and punctuation) H Cl CH2 CH C CH 1-buten-3-yne 4-chloro-3-methyl-1-cyclohexene CH2 C H CH2 CH C C C CH CH3 5-methyl-1,5-heptadien-3-yne H2C C CH3 CH3 CH CH H C C C C CH CH CH3 2-hepten-4,6-diyne CH2 CH2 1-cyclohexylheptane CH3 (CH2)6 HC CH2 (note that the carbon chain has more Groups derived from alkenes, alkynes or combined hydrocarbons are named by dropping the CH2 CH2 carbons than the ring) final "e" and replacing it by "yl". The chain is renumbered to give the carbon with the free valence the number 1 position: Examples (note positions of numbers and punctuation) H C C CH CH CH2 2-penten-4-ynyl group H C C CH2 2-propynyl group CH3 CH CH CH2 2-butenyl group H C C ethynyl group Special Note: The following have special names: CH2 CH vinyl group CH2 CH CH2 allyl group H C C CH2 propargyl group (v) Cyclic Hydrocarbons Compounds with hydrocarbon rings are named by the insertion of "cyclo"- before the name of the hydrocarbon corresponding to the open chain compound containing the same number of carbons. Examples CH2 Cyclopropane H2C CH2 CH2 CH2 Cyclohexane H2C CH2 CH2 CH2 9 10 3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS 3 COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES The halogens (F, Cl, Br, I) and the nitro group (-NO2) are always named as prefixes in the (i) General Naming Scheme same way as side chains on hydrocarbons. The prefixes are as follows: The name of every organic molecule containing a functional group whose name appears as Group Prefix a suffix may be thought of as made up of four parts: F- fluoro Numbers Prefixes Stem Suffix Cl- chloro Locates the Substituents in The name of the Identifes the Br- bromo substituents in alphabetical order pricipal (longest) principal I- iodo the molecule chain functional group NO2- nitro The Principal Functional Group (PFG) whose suffix name is used is selected from Table 2 The list is in order of decreasing priority. Examples Table 2. Table of Functional Groups (descending order of priority) CH3 I Iodomethane Class Formula Prefix Suffix CH3 CH CH3 Cation -NR3+ ammonio- -ammonium 2-chloropropane Carboxylic acid -COOH carboxy- -oic acid Cl Sulfonic acid -SO2OH sulfo- -sulfonic acid CH3 Salt of Carboxylic Acid -COO- M+ carboxylato- cation name..-oate 2-bromo-2-methylpropane Ester -COOR R-oxycarbonyl- R-…-oate CH3 C CH3 Acid Halide C X haloformyl- -oyl halide Br O CH3 CH2 Amide C NH2 carbamoyl- -amide 3-ethyl-1-fluoropentane O CH3 CH2 CH CH2 CH2 F Nitrile C N cyano- -nitrile CH3 CH2 NO2 nitroethane Aldehyde C H formyl- -al O CH2 CH2 CH2 1-bromo-3-chloropropane Ketone C oxo- -one Cl Br O CH2 CH CH2 CH2 Cl 4-chloro-1-butene Alcohol -OH hydroxy- -ol Thiol -SH mercapto- -thiol Special Note: The following have special names: Amine -NH2 amino- -amine F3C H fluoroform Imine =NH imino- -imine Ether -OR R-oxy- - Cl3C H chloroform Thioether -SR R-thio- - Br3C H bromoform I3C H iodoform Wherever "R" appears in the prefix or suffix table then the group name (i.e. alkyl, alkenyl, carbon tetrachloride etc.) for the R group is used. CCl4 CBr4 carbon tetrabromide 11 12 A. Choosing the Principal Chain (ii) Naming Various Classes of Organic Compounds The Principal Chain is chosen according to the following rules, applied in order: A. Ethers and Thioethers (a) The chain must contain the (maximum number of) principal functional group(s); In the naming of ethers as alkyloxy derivatives of alkanes, it is general practice to shorten then the names of compounds containing four or less carbons to alkoxy derivatives (i.e., omit the (b) it must contain the maximum number of double and triple bonds; then syllable "-yl-°'), e.g., methyloxy becomes methoxy, ethyloxy becomes ethoxy, but pentyloxy (for CH3CH2CH2CH2CH2O-) is correct. (c) it must be the longest possible carbon chain (the carbons of the -CO2H, -CΞN, -C(=O)H etc. groups are counted when they form part of the principal chain). An alternative system for naming ethers (or thioethers) is to name the alkyl groups on oxygen (sulfur) and list them in alphabetical order as separate words before the name "ether" (or B. Naming the Principal Chain sulfide). The principal chain is named after the alkane having the same number of carbon atoms, and Examples is modified when unsaturated by the replacement of “ane" by "en(e)", "enyn(e)", "adiene", etc. The final “e” of the name is omitted before "y" or a vowel (e.g. methaneol becomes CH3 CH2 O CH2 CH3 diethyl ether or ethoxyethane methanol). C. Numbering the Principal Chain CH3 CH3 CH CH3 isopropyl methyl ether or 2-methoxypropane The principal chain is numbered according to the following rules, taken in order: O (a) the PFG.'s must be given the lowest possible numbers; then ethyl propyl sulfide or 1-ethylthiopropane CH3 CH2 CH2 S CH2 CH3 (b) the double and triple bonds must be given the lowest possible numbers; then (c) the remaining functional groups and substituents must be given the lowest possible numbers. B. Alcohols and Thiols (a) -OH or -SH as the principle functional group The following example illustrates the basic approach to naming: Examples CH3 OH methanol HO CH2 CH CH C C CH3 CH3 Cl O CH3 SH methanethiol Principal group C -one CH3 O 2-propanol CH3 CH OH Principal chain C C C C C C hexane CH2 CH2 CH2 CH2 Principal chain name plus 1,4-butanediol C C C C C C OH OH principal group 2-hexanone O CH2 CH2 CH2 1,3-propanedithiol SH SH Modified name ("ane" 6 5 4 3 2 1 3-hexen-2-one becomes "en") C C C C C C CH3 CH CH CH2 2-buten-1-ol O OH Prefixes (alphabetical with 3-chloro cyclohexanethiol Cl SH location number) OH 6-hydroxy CH3 5-methyl Complete name: 3-chloro-6-hydroxy-5-methyl-3-hexen-2-one 13 14 (b) -OH or -SH as other than the principle functional group Table 3 lists the carboxylic acids that have have special (trivial) names which are preferred to the formal (systematic) names. Examples Table 3. Special Names of Common Carboxylic Acids CH2 CH2 CH2 CH2 C H 5-hydroxypentanal Formula Trivial Name Systematic Name OH O H C OH formic acid methanoic acid CH3 CH2 CH CH CH C OH O 4-hydroxy-2-hexenoic acid OH O acetic acid ethanoic acid CH3 C OH CH2 CH2 CH2 O 3-mercapto-1-propanol OH SH CH3 CH2 C OH propionic acid propanoic acid O Alcohol and Thiol Salts The salts of alcohols and thiols are most simply named by adding "-ate" after the "-ol" of the CH3 CH2 CH2 C OH butyric acid butanoic acid name. Alternatively, the alcoholates may be named as alkyloxides (dropping the "yl" syllable for the first four members as in ether naming). O Examples HO C C OH oxalic acid ethanedioc acid sodium methoxide or sodium methanolate CH3 O- Na+ O O potassium pentyloxide or potassium pentanolate malonic acid propanedioic acid CH3 CH2 CH2 CH2 CH2 O- K+ HO C CH2 C OH O O C. Acids, Salts of Acids and Acid Anhydrides succinic acid butanedioic acid HO C CH2 CH2 C OH Carboxylic acids are named by identifying the longest carbon chain containing the carboxylic acid functional group and using this carbon chain as the stem for the carboxylic acid name. O O The ending "-anoic acid" is added to the stem to indicate that the compound is a carboxylic acid. COOH fumaric acid E-butenedioic acid H Examples HOOC H CH3 CH2 CH2 CH2 CH2 C OH hexanoic acid H H maleic acid Z-butenedioic acid O CH3 CH2 CH CH C OH HOOC COOH 2-bromo-3-methylpentanoic acid CH3 Br O CH3 CH C OH lactic acid 2-hydroxypropionic acid OH O CH2 CH CH CH2 CH3 2-ethyl-3-butenoic acid COOH The stem name formed by removal of "-ic" from the trivial name is also used in naming other acid derivatives and aldehydes. 15 16 Acid anhydrides are named when symmetrical by replacement of the word "acid" by E. Acid Halides anhydride. When unsymmetrical, the two acid groups are named as separate words in Acid halides are maned by replacing the "-ic acid" ending of the parent carboxylic acid with alphabetical order and the word anhydride is added. "-yl halide”. Examples Examples CH3 C O C CH3 acetic anhydride CH3 C Cl acetyl chloride O O O CH3 CH2 CH2 C O C CH3 acetic butyric anhydride CH3 CH2 C Br propionyl bromide O O O CH3 Acid salts are named by replacicing the “ic” ending of the acid name with “ate”. 2-methylpentanoyl bromide CH3 CH2 CH2 CH C Br Examples O sodium butyrate CH3 CH2 CH2 C O- Na+ O F. Amides - ammonium acetate Primary amides are named by identifying the carboxylic acid from which the amide is derived CH3 C O NH4+ and replacing the "-ic acid" or "-oic acid" ending of the parent carboxylic acid name with the O ending "-amide". CH3 When there are substituents on the N atom, these are named using N-alkyl or N,N-dialkyl as prefixes (note N or N,N are italicised) immediately before the main chain name. - + potassium 5,5-dimethylhexanoate CH3 C CH2 CH2 CH2 C O K Examples CH O 3 CH3 C NH2 acetamide 2+ calcium formate (or calcium diformate) O Ca (HCO 2-)2 CH3 CH2 CH2 CH2 CH2 CH2 C NH2 heptanamide D. Esters O The alkyl (alkenyl etc.) group on oxygen is named as a separate word and is followed by the CH3 CH2 CH2 C NH N-methylbutyramide acid salt name ("-ic acid" becomes "-ate"). O CH3 Examples CH3 CH2 C O CH2 CH3 ethyl propionate CH3 N,N-dimethylformamide O H C N propyl formate O CH3 H C O CH2 CH2 CH3 O 6-methyl-N-ethyl-N- CH3 CH CH2 CH2 CH2 CH2 C N CH2CH3 propylheptanamide CH3 CH CH C O CH2 CH2 CH3 propyl 2-butenoate CH3 O CH2CH2CH3 O CH3 CH3 CH2 CH2 C O CH CH3 isopropyl butyrate O 17 18 G. Nitriles Cl The nitriles formed from acids with trivial names are named by replacing the “ic acid” ending 5-chlorohexanal of the parent carboxylic acid with "-onitrile". Otherwise, "-nitrile" is used as a suffix to the CH3 CH CH2 CH2 CH2 C H stem name of the parent alkane. O Examples CH3 CH2 CH2 CH2 CH2 CH CH CH2 C H 3-nonenal CH3 CN acetonitrile O CH3 CH2 CH2 CH2 CH2 CH2 CN heptanenitrile Special Note: the compound CH3 2-hydroxy-2-methylpropanenitrile H C C H has the special name glyoxal CH3 C CN O O OH Cl 2-chloropentanenitrile Special Note: The prefix "formyl" is only used when a functional group of higher priority is CH3 CH2 CH2 CH CN present. hydrogen cyanide (not formonitrile) H C CH2 CH2 CH2 CH2 C OH 5-formylpentanoic acid H CN O O Special Note: The prefix "cyano" is only used when a functional group of higher priority is + (4-formylbutyl)trimethylammonium present. H C CH2 CH2 CH2 CH2 N(CH3)3 Br- bromide CH3CH2 CH CH2 COOH 3-cyanopentanoic acid O CN methyl cyanoacetate Derivatives of aldehydes and ketones, e.g. oximes or hydrazones are named simply by NC CH2 C OCH3 adding the word oxime etc. after the aldehyde or ketone name. O Examples CH3 CH2 CH2 C H butyraldehyde oxime H. Aldehydes N OH Aldehydes formally derived from acids having a trivial name are named by adding "-aldehyde" to the trivial stem (see Section 3), otherwise the suffix “-al” is used. acetone oxime CH3 C CH3 Examples N OH H C H formaldehyde cyclohexanone hydrazone O NHNH2 CH3 C H acetaldehyde CH3CH2 C CH2CH3 3-pentanone oxime O NOH CH3 CH2 CH2 C H butyraldehyde (or butanal) O 19 20 I. Ketones J. Amines and Ammonium Salts Ketones are named by adding the suffix "-one" to the stem of the parent carbon chain. The systematic method of naming amines, whereby "-amine" is added to the principal chain name is, in practice, only rarely used and an older method is in common (I.U.P.A.C. Examples accepted) use. Amines are named as derivatives of ammonia. The longest chain attached CH3 C CH2 CH3 butanone to the nitrogen atom is named in the usual way for an alkyl group (the carbon attached to the nitrogen is carbon 1). Any other N-substituents are named as N-alkyl, or N,N-dialkyl O substituents. The alkyl name for the longest stem is then added to the suffix "amine". 3-pentanone Examples The following examples show this common naming in practice (together with CH3 CH2 C CH2 CH3 the formal, systematic names in parenthesis): O methylamine (methanamine) CH3 NH2 cyclopentanone O CH3 NH dimethylamine (N-methylmethanamine) CH3 CH3 CH CH2 C CH2 CH3 5-methyl-3-hexanone CH3 O CH3 dimethylamine (N,N-dimethylmethanamine) CH3 NH CH3 C CH2 CH2 CH2 C CH3 2,6-heptanedione CH3 O O CH2CH3 H 4-ethylcyclohexanone O N-ethyl-N-methylpentylamine (N-ethyl-N-methyl- CH3CH2CH2CH2CH2 N CH3CH2 1-pentanamine) CH3 Special Note: the following compounds have special names: CH2CH3 1-ethyl-N-methylbutylamine CH3 C CH3 acetone CH3CH2CH2CH NH (N-methyl-3-hexanamine) O CH3 CH3 C C CH3 biacetyl Imines are best named systematically O O Examples CH3CH NH ethanimine Special Note: The prefix "oxo" is used when the ketone is not the principal functional group. Examples CH3CH2CH2CH NCH2CH3 N-ethyl-1-butanimine CH3 C CH2 CH2 C H 4-oxopentanal O O Ammonium Salts are named as alkyl derivatives of inorganic ammonium salts. Note that the N- system is not used and the four alkyl groups attaached to N are listed alphabetically. CH3CH2 C CH2CH2COOH 4-oxohexanoic acid Examples O (CH3)4N+ I- tetramethylammonium iodide CH2CH3 + - diethylhexylmethylammonium chloride CH3CH2CH2CH2CH2CH2 N CH3 Cl CH2CH3 21 22 5 AROMATIC COMPOUNDS (iii) Substituted Aromatic Compounds (i) General Notes A. Halogen and Nitro- Substituted Aromatics The use of numbers to indicate the position of substituents on aromatic rings is These are named using halo- or nitro- prefixes before the name of the aromatic supplemented in the case of disubstituted derivatives of benzene by the terms: hydrocarbon in the usual way. ortho- abbreviated o- indicating 1,2-disubstitution Examples meta- abbreviated m- indicating 1,3-disubstitution Cl NO2 para- abbreviated p- indicating 1,4-disubstitution chlorobenzene nitrobenzene Examples Br NO2 NO2 1-chloro-2,4- benzene Cl o-bromochlorobenzene dinitrobenzene p-dinitrobenzene O2N Cl NO2 I Cl m-iodonitrobenzene p-chloronitobenzene B. Carboxylic Acids and Derivatives NO2 The following list gives the trivial (usually accepted) names for some of the common aromatic NO2 acids and derivatives. COOH COOH benzoic acid CH3 o-toluic acid (ii) Aromatic Hydrocarbons The following aromatic compounds have the special name and derived group names shown below: 1 phenyl group COOH COOH 6 2 m-anisic acid phthalic acid benzene (abbreviated –Ph) COOH 5 3 OCH3 4 CH3 CH3 tolyl group COOH Br COOH toluene (o-tolyl shown) m-nitrobenzoic 3,5- acid dibrombenzoic acid anisyl group NO2 Br OCH3 OCH3 anisole (o-anisyl shown) NO2 COOH COOH 2,4,6- 2-naphthoic acid CH2CH3 CH2 benzyl group trinitrobenzoic acid ethylbenzene (abbreviated -Bz) O2N NO2 1 NO2 COOH 8 naphthyl group 2 COOH 6-nitro-o-toluic 6-bromo-2- 7 naphthalene (2-naphthyl shown) acid Br naphthoic acid 6 3 CH3 5 4 23 24 Carboxylic acid Derivatives When the -OH group is not the principal functional group, "hydroxy" is used in the usual way. Acid derivatives, esters, anhydrides, amides and nitriles are named in the usual way, Example replacing "-oic" or "-ic" of the acid name with the appropriate endings. OH OH Examples p-hydroxybenzoic acid p-hydroxybenzonitrile COO Na - + COCl sodium benzoate m-anisoyl chloride (from m-anisic acid) COOH CN OCH3 CN CONH2 D. Aldehydes and Ketones benzonitrile Cl o-chlorobenzamide Aldehydes are named by replacing the "-ic" or "-oic" of the acid name by "aldehyde”. Examples O O O benzaldehyde o-tolualdehyde C C O propyl benzoate C methyl o-toluate H H CH3CH2CH2 C OCH3 O CH3 CH3 O O O C o-nitrobenzaldehyde C salicylaldehyde O p-chlorophenyl C phthalic anhydride H H C benzoate O NO2 OH Cl O C O O C p-hydroxybenzaldehyde H C. Phenols and Thiophenols HO Phenols have an –OH group attached directly to an aromatic ring. OH OH Aromatic ketones are named by changing the "ic" or "oic" ending of the acid name phenol 2-naphthol corresponding to the acyl group attached to the benzene ring to "-ophenone" Examples O O OH OH acetophenone propiophenone C C m-cresol 3,4-dibromophenol CH3 CH2CH3 CH3 Br O Br C m-nitrobutyrophenone CH2CH2CH3 SH thiophenol (or benzenethiol) NO2 25 26 Aldehydes and ketones in which the carbonyl group is not directly attached to the aromatic F. Aromatic Amines ring are named using the corresponding group name for the aromatic system as a prefix. Special Names Examples NH2 NH2 CH2CHO aniline m-toluidine phenylacetaldehyde CH3 O CH2 C CH2CH3 1-(m-nitrophenyl)-2-butanone NH2 NH2 p-anisidine o-phenylene CH3O NH2 diamine NO2 The remaining aromatic amines are named as derivatives of these or (in the presence of E. Sulfonic Acids and Sulfonic Acid Derivatives more important functional groups) as "amino-" derivatives, or as "phenylamines". Sulfonic acids are named by adding the suffix "-sulfonic acid". Examples Examples NH2 2,4,6-tribromoaniline SO3H Br Br benzenesulfonic acid SO3H o-hydroxybenzenesulfonic acid Br OH diphenylamine p-toluenesulfonic acid N SO3H H CH3 NHCH3 NO2 2,4-dinitro–N-methylaniline Sulfonic Acid Derivatives. Derivatives of sulfonic acids (esters, amides and sulfonic acid chlorides) are named by analogy with carboxylic acids. Examples NO2 SO2OCH3 methyl o-toluenesulfonate Ammonium Salts CH3 These are named by changing the "-e" of the special names to “-ium". SO2NH2 Examples benzenesulfonamide + - NH3 Cl anilinium chloride SO2Cl m-nitrobenzenesulfonyl chloride + - 3-nitro-N,N-dimethylanilium (CH3)2NH Br bromide. NO2 NO2 27 28 Acyl Derivatives (Amides) C. Ketones Simple acyl derivatives are named by adding the trivial acid name stem to "-anilide" etc. CH3 CH3 CH3CH2 CH3 ethyl methyl C C ketone Example dimethyl ketone O O H acetanilide O O methyl vinyl N CH3 ketone C C methyl phenyl ketone CH2 CH C CH3 O CH3 G. Diazonium Ions (ArN2+) These are named in an analogous fashion to sulfonic acids; the syllable "-diazonium" is D. Nitriles (Cyanides) added to the aromatic name. methyl cyanide CH3CN CH2CN Examples benzyl cyanide + N2 benzenediazonium ion E. Grignard Reagents + - N2 HSO4 CH3CH2MgBr ethyl magnesium MgCl phenyl p-bromobenzenediazonium bromide magnesium hydrogen sulfate chloride Br 6. RADICOFUNCTIONAL NAMING An alternate system of naming, which is still very common in many textbooks, consists of naming the alkyl or aryl groups attached to a certain functional group as separate words followed by the functional group name. The alternative naming of ethers and amines is a remnant of this system. The following examples suffice to illustrate the system. A. Alkyl Halides CH3 I methyl iodide (CH3)2CHBr isopropyl bromide (CH3)3CCl tert-butyl chloride CH2Cl benzyl chloride B. Alcohols CH3OH methyl alcohol (CH3)3COH tert-butyl alcohol CH2OH benzyl alcohol Revised and updated Professor L D Field May 2004 29 30