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John E. McMurry www.cengage.com/chemistry/mcmurry Lecture 02 Drawing Structures, Functional Groups, Nomenclature, Isomerism Paul D. Adams • University of Arkansas Representing Organic Compounds Compounds can be represented in many different ways. Some representations provide information about the structure, while others do not. Molecular Formula: Number of atoms of each element in one molecule of a compound (no structural information). Ex. C6H14 Empirical Formula: Relative ratio’s of elements present. Ex. CH2O could be CH2O or C2H4O2. Line bond (Kekule) Structures: Show all atoms and bonds. Condensed Structures: Show all atoms, but only show bonds when necessary. Skeletal Structures: Show C-C bonds and all atoms that are not C or H. Representing Organic Compounds Structural Formula Condensed Structural Formula H H H H H C C C C H H H H Also called Line-bond or Kekule structures. CH3CH2CH2CH3 CH3(CH2)2 CH3 Learn this quickly, it will save you much time. Skeletal Structure Molecular Formula H C4H10 3.2 Alkanes and Alkane Isomers Alkanes: Compounds with C-C single bonds and C-H bonds only (no functional groups) Connecting carbons can lead to large or small molecules The formula for an alkane with no rings in it must be CnH2n+2 where the number of C’s is n Alkanes are saturated with hydrogen (no more can be added They are also called aliphatic compounds Isomerism Isomers: Compounds that have identical molecular formulas, but different arrangement of atoms. Constitutional (Structural) isomers: Same formula, different arrangement. Stereoisomers: Same formula, same arrangement, different 3D orientation. Ex. Structural Isomers of C2H6O. At room temp: Ethyl alcohol is a liquid, completely soluble in water. Dimethyl ether is a gas, partially soluble in water. Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011 Isomerism H H C H H H H C C H H H H H C C C H Constitutional (Structural isomers): Same formula, H H different arrangement. H H H H H H H C H H C H H C H n-Butane H H C C H H H H H C C C H H H H isobutane H 3D Conformations of Alkanes Molecules are not static, but in constant motion. They, twist, turn, bend, vibrate, rotate around C-C bonds. Rotation produces different conformations. H3C H3C H3C CH3 CH3 CH3 H3C H3C H3C CH3 CH3 CH3 Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011 Recognizing Isomers • Different conformations are not the same as structural isomers (butane, isobutene) • Two structures are STRUCTURAL ISOMERS only if bonds have to be broken and remade to convert one to the other. Constitutional Isomers Alkyl Substituents Alkyl groups: substituents (branches) on parent alkane. #C 1 2 3 4 5 6 7 8 9 10 Name methane ethane propane butane pentane hexane heptane octane nonane decane Alkyl Group methyl ethyl propyl butyl pentyl hexyl heptyl octyl nonyl decyl Isomers? No No No Yes Yes Yes Yes Yes Yes Yes substituent parent Alkyl Groups (Continued) Classifications of Carbons, Hydrogens Common Alkyl Groups Parent alkane methane ethane propane n-butane isobutene Parent structure CH4 CH3CH3 CH3CH2CH3 Alkyl group structure --CH3 --CH2CH3 --CH2CH2CH3 Alkyl group name methyl ethyl propyl CH3CH2CH2CH3 | CH3CHCH3 --CH2CH2CH2CH3 isopropyl butyl CH3 | CH3CHCH3 | CH3CHCH2CH3 CH3 | --CH2CHCH3 CH3 | CH3CCH3 | sec-butyl Isobutyl t-butyl 3.4 Naming Alkanes Compounds are given systematic names by a process that uses substituent parent 3-methylhexane 4-ethyl-3-methylheptane Naming Alkanes (Continued) Find the longest continuous C chain. This is the Parent. If 2 different chains of equal length are present, the parent is the one with the MOST branch points. Number the atoms in the parent chain. Begin numbering at the end nearest the 1st branch point. If 1st point is the same at either end, begin at end nearest the 2nd, 3rd branch points. We want to label this so that branch points are the lowest numbers possible. If the numbering is the same in both directions, then use alphabetical order to break the tie. Naming Alkanes (Continued) Identify and number the substituents. Assign a number to each substituent based on carbon number in parent chain. Two substituents on the same carbon (not 3) get the same number. If both substituents are the same, use the prefix di-. If structure has multiple identical substituents, put them altogether in the name. For example: 2,3,4,5,6pentamethyloctane. Naming Alkanes (Continued) Write name as a single word. Separate prefixes with hyphens. Use commas (no spaces) to separate numbers. If 2 or more different substituents are present, cite in alphabetical order. Multiplier prefixes (di-, tri-, tetra-, penta-, etc.) are NOT used for alphabetizing. The prefixes sec- and t- are NOT used for alphabetizing, but iso- IS used for alphabetizing. Naming Alkanes (Continued) When substituents are alphabetized, iso- and cyclo are used as part of the alkyl group name, but the hyphenated prefixes are not (except for complex substituents). Thus isobutyl is alphabetized with i, but n-butyl, tert-butyl, and sec-butyl are alphabetized with b. Examples: Naming Alkanes H3C Cl H3C H3C CH3 CH3 CH3 H3C CH3 H3C H3C CH3 CH3 CH3 CH3 CH3 CH3 H3C CH3 CH3 H3C H3C Cl CH3 CH3 H3C CH3 H3C CH3 H3C CH3 CH3 CH3 H3C CH3 H3C CH3 Br CH3 Br Examples: Naming Alkanes H3C Cl H3C H3C CH3 CH3 CH3 H3C CH3 5-sec-butylnonane H3C CH3 CH3 CH3 2-chloro-2,4-dimethylpentane H3C CH3 CH3 5-sec-butyl-4-methylnonane CH3 H3C CH3 CH3 H3C H3C Cl CH3 2,2-dimethylbutane CH3 3-ethyl-3-methylpentane 1-chloro-3-isopropylcyclopentane H3C CH3 H3C CH3 H3C CH3 CH3 CH3 1,2,4-trimethylcyclohexane H3C CH3 H3C CH3 Br Br CH3 2,2,4,6,6-pentamethylheptane 3,5,dibromo-4-ethylheptane Complex Substituents (method 1) Complex alkyl groups are named by using the longest carbon chain starting at the point of attachment to the main chain(this is Carbon 1). Continue to name as if this were a mini-tree (same rules for alkanes). CH2CH3 1 2 CH3 3 CH CH CH3 CH3 a (1-ethyl-2-methylpropyl) group 1 C 2 CH2 CH3 3 CH 4 CH3 CH3 a (1,1,3-trimethylbutyl) group When naming involves complex substituents, the first letter in the complex substituent, regardless of type, is used for alphabetizing Complex Substituents (method 2) Complex alkyl groups are named by using the longest carbon chain, but not necessarily starting at the point of attachment. Number chain so first branch gets lowest number, and include number indicating the point of attachment to main chain. Method 1 5-(1-ethyl-2-methylpropyl) decane Method 2 5-(2-methylpentan-3-yl)decane When naming involves complex substituents, the first letter in the complex substituent, regardless of type, is used for alphabetizing Naming Complex Substituents Naming Complex Substituents 3-ethyl-7-methyl-5-(2methylbutyl)nonane 3-ethyl-4,6-dimethyl-5(1-methylbutyl)nonane 7-ethyl-2,6-dimethyl-5(1-methylbutyl)nonane 3,7-diethyl-2,4,6-trimethyl5-(3-methylbutyl)nonane 7-ethyl-2,4,6-trimethyl-5(1-methylbutyl)nonane 4,5-diisobutyl-2,2,6,7tetramethyloctane 4.1 Naming Cycloalkanes Cycloalkanes are saturated cyclic hydrocarbons Have the general formula (CnH2n) Naming Cycloalkanes 1) Find the parent. # of carbons in the ring. 2) Number the substituents to get the lowest number set possible. Cycloalkanes as substituents If the number of carbon atoms in the largest acyclic substituent is greater than the number of carbons in the ring, the cycloalkane is a substituent. sec-butylcyclohexane 4-cyclohexylheptane 4.2 Cis-Trans Isomerism in Cycloalkanes Cycloalkanes are less flexible than open-chain alkanes Much less conformational freedom in cycloalkanes Cis-Trans Isomerism in Cycloalkanes (Continued) - Because of their cyclic structure, cycloalkanes have 2 faces as viewed edge-on “top” face “bottom” face Therefore, stereoisomerism (Same formula, same arrangement, different 3D orientation) is possible in substituted cycloalkanes There are two different 1,2-dimethylcyclopropane isomers 3.1 Functional Groups Functional group - collection of atoms at a site that have a characteristic behavior in all molecules where it occurs The group reacts in a typical way, generally independent of the rest of the molecule For example, the double bonds in simple and complex alkenes react with bromine in the same way Functional Groups with Multiple Carbon–Carbon Bonds Alkenes have a C-C double bond Alkynes have a C-C triple bond Arenes have special bonds that are represented as alternating single and double C-C bonds in a sixmembered ring Functional Groups with Carbon Singly Bonded to an Electronegative Atom Functional Groups with a Carbon–Oxygen Double Bond (Carbonyl Groups) Survey of Functional Groups Survey of Functional Groups Alkenes Alkynes contain a double bond. General formula is CnH2n. Each double bond has 1 degree of unsaturation. Geometry is triangular. 7.3 Naming Alkenes 1. 2. 3. 4. 5. 6. 7. 8. Name the longest chain that contains the double bond or double bonds. Replace the –ane from the alkane name with –ene. Number this longest chain so the C=C bond or bonds has/have the lowest number. The locant(s), i.e., positional identifiers, for the double bond is assigned to the first C of each C=C bond. Name the attached functional groups. Combine the names of the attached groups and longest chain, the same as you would with alkanes. For multiple double bonds, indicate the locations of all multiple bonds, drop only the –ne from the alkane, and attach numeric prefixes indicating the number of double bonds (-diene, -triene, -tetraene). For alkenes with a single double bond, indicate cis- or trans- when applicable. If alkenes have more than 1 double bond, use E, Z nomenclature. 7.3 Naming Alkenes Name the parent hydrocarbon Number the carbons in chain so that double bond carbons have lowest possible numbers Naming Alkenes (Continued) Br (2E)-but-2-ene 2-methylpent-2-ene (3Z)-3-methylhex-3-ene (3E)-3-bromo-4-methylhex-3-ene Cl I (3Z)-3,4,5-trimethylhept-3-ene (4Z)-3,4,7-trimethylocta-1,4,6-triene H Cl 4-methylcyclohexene 5-chlorocyclopenta-1,3-diene (2Z,4E)-1-chloro-5-iodo-2,4-dimethylhexa-2,4diene Br (5S)-5-bromocyclohexa-1,3-diene Many Alkenes Are Known by Common Names Cis-Trans Isomerism in Alkenes Rotation of bond is prohibitive This prevents rotation about a carbon-carbon double bond (unlike a carbon-carbon single bond). Creates possible alternative structures Cis-Trans Isomerism in Alkenes (Continued) the presence of a carbon-carbon double bond can create two possible structures cis isomer - two similar groups on same side of the double bond trans isomer - similar groups on opposite sides Each carbon must have two different groups for these isomers to occur Cis-Trans Isomerism in Alkenes (Continued) Cis-Trans Isomerization requires that end groups differ in pairs Bottom pair cannot be superposed without breaking C=C 7.5 Alkene Stereochemistry and the E,Z Designation Cis-Trans naming system discussed thus far only works with disubstituted alkenes Tri- and Tetra substituted double bonds require more general method Method referred to as the E,Z system Alkene Stereochemistry and the E,Z Designation (Continued): E,Z Stereochemical Nomenclature Priority rules of Cahn, Ingold, and Prelog Compare where higher priority groups are with respect to bond and designate as prefix E -entgegen, opposite sides Z - zusammen, together on the same side Alkene Stereochemistry and the E,Z Designation (Continued): Cahn-Ingold-Prelog Rules RULE 1 Must rank atoms that are connected at comparison point Higher atomic number gets higher priority Br > Cl > S > P > O > N > C > H Alkene Stereochemistry and the E,Z Designation (Continued): Cahn-Ingold-Prelog Rules RULE 2 If atomic numbers are the same, compare at next connection point at same distance Compare until something has higher atomic number Do not combine – always compare Alkene Stereochemistry and the E,Z Designation (Continued): Cahn-Ingold-Prelog Rules RULE 3 Multiple-bonded atoms are equivalent to the same number of single-bonded atoms Substituent is drawn with connections shown and no double or triple bonds Added atoms are valued with 0 ligands themselves Alkynes Alkynes contain a triple bond. General formula is CnH2n–2. Each triple bond has 2 degrees of unsaturation Geometry is linear. H3C C C CH2 CH3 9.1 Naming Alkynes Name of the compound ends in -yne. Longest chain chosen for root name must include both C atoms of triple bond. The root chain must be numbered from the end nearest a triple bond C atom. If the triple bond is in the center of the chain, the nearest substituent rule is used to determine the end where numbering starts. The smaller of the 2 numbers designating C atoms of triple bond is used as the triple bond locator. If several multiple bonds are present, each must be assigned a locator number. Double bonds precede triple bonds in the IUPAC name, but the chain is numbered from the end nearest a multiple bond, regardless of its nature. The name will then have multiplier prefix (e.g., diyne, triyne, etc.) If double and triple bonds are tied numerically, double bond takes precedence. Because the triple bond is linear, it can only be accommodated in rings larger than 10 carbons. In simple cycloalkynes the triple bond carbons are assigned ring locations #1 and #2. Which of the two is #1 may be determined by the nearest substituent rule. Substituent groups containing triple bonds are: HC≡C– Ethynyl group Examples: Naming Alkynes H3C CH3 but-2-yne H3C CH3 H3C CH3 H3C pent-2-yne CH3 hex-3-yne CH3 HC Br 2-bromohex-3-yne Br 5-bromohexa-1,3-diyne Examples: Naming Alkynes Cl Examples: Naming Alkynes hepta-1,5-diyne hept-1-en-5-yne (3E)-hepta-1,3-dien-5-yne Cl (5E)-hept-5-en-1-yne 5-chlorohept-1-en-6-yne 15.1 Naming Aromatic Compounds Many common names (toluene = methylbenzene; aniline = aminobenzene) Monosubstituted benzenes systematic names as hydrocarbons with –benzene C6H5Br = bromobenzene C6H5NO2 = nitrobenzene, and C6H5CH2CH2CH3 is propylbenzene Aromatics 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. Naming Benzene Derivatives 1. For single replacement (H some FG), cmpd named as a benzene derivative. CH3 O + O - N propylbenzene H3C nitrobenzene CH3 isopropylbenzene OH CH3 methylbenzene O hydroxybenzene OH carboxybenzene Naming Benzene Derivatives (Continued) 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. CH3 CH3 CH3 CH3 CH3 CH3 oO H3C + N O - m- pNH2 Cl Cl CH3 o-nitrotoluene m-dichlorobenzene p-methylaniline p-aminotoluene Naming Benzenes with More Than Two Substituents 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) The Phenyl Group When a benzene ring is a substituent, the term phenyl is used (for C6H5 ?) You may also see “Ph” or “f” in place of “C6H5” “Benzyl” refers to “C6H5CH2 ?” Benzene as a Phenyl group • The benzene ring can also be an attached substituent group. H3C CH3 4-phenylheptane 1,1-diphenylcyclobutane Alcohols and Phenols Alcohols contain an OH group connected to a saturated C (sp3) They are important solvents and synthesis intermediates Phenols contain an OH group connected to a carbon in a benzene ring Methanol, CH3OH, called methyl alcohol, is a common solvent, a fuel additive, produced in large quantities Ethanol, CH3CH2OH, called ethyl alcohol, is a solvent, fuel, beverage OH groups bonded to vinylic sp2-hybridized carbons are called enols Classifications of Alcohols General classifications of alcohols based on substitution on C to which OH is attached Methyl (C has 3 H’s), Primary (1°) (C has two H’s, one R), secondary (2°) (C has one H, two R’s), tertiary (3°) (C has no H, 3 R’s) 17.1 Naming of Alcohols Step 1: Identify longest chain that includes the (-OH) group(s). If 1 alcohol, drop –e from hydrocarbon name, and replace with –ol. If multiple alcohols, do NOT drop –e, but add –ol suffix, modified with numeric prefix (diol, triol, tetraol, etc.). Step 2: Number this parent chain to give lowest number to carbon with attached (-OH) group. Assign positional identifier(s) of (-OH) group(s). Step 3: Locate and name all branches attached to parent chain. Step 4: Include names of all branches (still in alphabetical order) in prefix of compound name. Include location of (-OH) group. 1 5 H3C 2 4 3 OH H3C 2 3 CH3 2-ethyl-1-pentanol HO 1 4 OH 2-methyl-1,4-butanediol Naming of Alcohols HO CH3 H3C OH CH3 Br HO H3C H3C OH CH3 OH CH3 OH H3C H3C OH OH H3C CH3 HO CH3 H3C H3C OH CH3 H3C CH3 OH OH OH CH3 Naming of Alcohols HO CH3 H3C OH CH3 Br HO H3C H3C OH CH3 2,2,4-trimethyl-3-hexanol OH CH3 5-bromo-3-ethyl-1-pentanol OH H3C H3C OH OH 1,2,4-hexanetriol H3C CH3 HO CH3 3-butyl-2,4-hexanediol H3C H3C 2,2-dimethylcyclopentanol H3C OH CH3 3-methyl-3-pentanol CH3 OH OH OH CH3 1,2-cyclohexanediol 2-isopropyl-1-methylcyclopropanol 3-phenyl-1-propanol Ethers and Their Relatives An ether has two organic groups (alkyl, aryl, or vinyl) bonded to the same oxygen atom, R–O–R Diethyl ether is used industrially as a solvent Tetrahydrofuran (THF) is a solvent that is a cyclic ether Thiols (R–S–H) and sulfides (R–S–R) are sulfur (for oxygen) analogues of alcohols and ethers 18.1 Naming Ethers Common Names 1. 2. Name the two groups attached to the oxygen then add the word ether If both groups the same, can be named with prefix di-. IUPAC Names O-R group is alkoxy. The –yl ending of smaller R group is replaced by –oxy. O CH3 H3C butyl methyl ether 1-methoxybutane H3C H3C O p-methoxytoluene CH3 CH3 Cl CH3 H3C O dipropyl ether 1-propoxypropane CH3 isopropyl propyl ether 1-isopropoxypropane ethyl propyl ether 1-ethoxypropane H3C CH3 O CH3 CH3 O H3C CH3 O CH3 2-ethoxy-3,4dimethylhexane H3C O CH3 CH3 2-chloro-1-isopropoxypropane Naming Thiols Thiols: Sulfur analogs of alcohols (-SH instead of –OH) Chemically- similar (i.e., form similar compounds) More volatile (lower BP) than alcohols but less water-soluble Thiols stink! This is how skunks defend themselves Chopped onions emit propanethiol Thiols found in garlic Ethanethiol added to natural gas (methane) so you can smell a leak IUPAC Names for simple thiols The –SH group is a sulfhydryl group. Follow the same steps for naming as you do for alcohols, but do not modify alkane ending; instead add –thiol to end of parent. SH H3C H3C butanethiol SH SH CH3 2-butanethiol H3C CH3 CH3 2-methyl-3-hexanethiol 19.1 Naming Aldehydes and Ketones Aldehyde: Carbonyl group with one or two H attached. Named by replacing –e with –al (IUPAC). H The aldehyde C is always numbered as 1. Ketone: Carbonyl group with two C attached. • Named by replacing –e with – one (IUPAC). • Numbered from end closest to carbonyl group O R R O O H R H Naming Aldehydes Aldehydes are named by replacing the terminal –e of the corresponding alkane name with –al The parent chain must contain the –CHO group The –CHO carbon is numbered as C1 If the –CHO group is attached to a ring, use the suffix carbaldehyde Naming Aldehydes O H3C O H pentanal O Cl H3C H H 5-chloropentanal CH3 H CH3 O 2-ethylbutanal O H Cl Cl m-chloro-benzaldehyde 5-chloro-2-methylbenzaldehyde CH3 O H CH3 H3C O H CH3 3,4-dimethylhexanal O CH3 5-methoxy-2-methylbenzaldehyde Naming Ketones Replace the terminal -e of the alkane name with –one Parent chain is the longest one that contains the ketone group Numbering begins at the end nearer the carbonyl carbon Naming Ketones O O O H3C Cl CH3 Cl CH3 2-pentanone CH3 1-chloro-3-pentanone 5-chloro-2-pentanone O F O CH3 H3C CH3 4-ethylcyclohexanone CH3 2-fluoro-5-methyl-4-octanone Naming Ketones O O O O Cl butan-2-one 3,5-dimethylheptan-4-one 3-chloro-5-ethylheptan-4-one O O O but-3-en-2-one OH O 4-hydroxybutan-2-one octane-2,7-dione 3-methylcyclopentanone Cl O O O Cl Br 7-bromo-3-chloro-4-methylcyclooctanone cyclohex-2-en-1-one 3-chloro-5-ethyloct-7-en-1-yn-4-one Ketones/Aldehydes as Minor FGs, Benzaldehydes O H O O O O OH H O O O 3-oxopentanal 3,4-dioxopentanal 3,4-dioxopentanoic acid O O O Cl H H OH H O benzaldehyde O H O 3-chlorobenzaldehyde O O H 3-oxopropanoic acid O 2-formylbenzoic acid O O H methyl 3-oxopropanoate O O methyl 3-oxobutanoate If C=O is lower priority functional group • Ketone/aldehyde is oxo group • Aldehyde is formyl group (on benzene) • Aldehyde is higher priority than ketone Functional Group Priority 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Carboxylic Acids (3 O bonds, 1 OH) Esters (3 O bonds, 1 OR) Aldehydes (2 O bonds, 1H) Ketones (2 O bonds) Alcohols (1 O bond, 1 OH) Amines Alkenes, Alkynes O OH Alkanes Ethers OH Halides 2-ethyl-4-hydroxybutanoic acid The parent will be determined based on the highest priority functional group. 20.1 Naming Carboxylic Acids Identify the longest C chain including the carboxyl group. Number the parent chain so that carboxyl C has lowest number. So for monocarboxylic acids, this will be 1, and does not need to be numbered in naming. Drop final –e (or –ene from benzene) from parent chain and replace with – oic acid. Alternative Names Compounds with –CO2H bonded to a ring are named using the suffix -carboxylic acid The CO2H carbon is not itself numbered in this system Use common names for formic acid (HCOOH) and acetic acid (CH3COOH) – see Table 20.1 Nitriles, RCN 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 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 O O O CH3 O O O CH3 CH3 CH3 methyl ethanoate phenyl butanoate ethyl benzoate O H CH3 O O O CH3 CH3 isopropyl methanoate methyl benzoate Naming Amides, RCONH2 With unsubstituted NH2 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 O H3C CH3 N O H3C CH3 N,N-dimethylethanamide CH3 N H CH3 N-isobutylmethylbutanamide O O N NH CH3 N-ethyl-Nphenylbenzamide CH3 CH3 N,2-dimethylbenzamide IUPAC Names – Simple Amines For simple amines, the suffix -amine is added to the name of the alkyl substituent 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. H3C NH2 H3C CH3 NH2 3-Pentanamine H3C H3C H3C 3-Methyl-1-butanamine CH3 NH H3C HN CH3 N CH3 CH3 NH2 CH3 2-Hexanamine N-Methyl-2-butanamine H3C N-Methyl-2-hexanamine CH3 N,N-Dimethyl-2-hexanamine NH2 H3C CH3 N H3C H3C CH3 CH3 N-Ethyl-N-methyl-2-hexanamine NH2 H3C CH3 NH2 2,5-hexanediamine cyclohexylamine IUPAC Names – Amines with More Than One Functional Group Consider the –NH2 as an amino substituent on the parent molecule IUPAC Names – Multiple Alkyl Groups Symmetrical secondary and tertiary amines are named by adding the prefix di- or tri- to the alkyl group IUPAC Names – Multiple, Different Alkyl Groups Named as N-substituted primary amines Largest alkyl group is the parent name, and other alkyl groups are considered N-substituents Common Names of Heterocyclic Amines 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