NOMENCLATURE Dr. Sheppard CHEM 2411 Spring 2015 Klein (2 nd ed.) sections 4.1, 4.2, 4.14, 7.2, 8.3, 8.4, 10.2, 13.1, 14.2, 14.11, 18.2, 20.2, 21.2, 21.6, 23.2, Appendix

Nomenclature The naming of organic molecules 1800s: named by discoverers 1892: IUPAC system

Nomenclature All names have Substituents-MainChain Substituents are groups attached to the main chain MainChain consists of Parent-Infix-Suffix Parent tells you number of carbons in main chain Infix tells you if the carbon-carbon bonds are single bonds (saturated molecule) or double or triple bonds (unsaturated molecules) Suffix tells you the functional group of your molecule

Parent Number of carbonsParent name 1meth- 2eth- 3prop- 4but- 5pent- 6hex- 7hept- 8oct- 9non- 10dec- 11undec- 12dodec-

Infix “-an-” = only carbon-carbon single bonds (saturated) “-en-” = an alkene (double bond) is present (unsaturated) “-yn-” = an alkyne (triple bond) is present (unsaturated)

Suffix Functional groupSuffix alcohol-ol ether amine-amine nitrile-nitrile thiol-thiol sulfide aldehyde-al ketone-one carboxylic acid-oic acid ester-oate amide-amide acid chloride-oyl chloride acid anhydride-oic anhydride

Straight-chain Alkanes Main chain = carbon chain Infix = “-an-” Suffix = “-e” No substituents

Nomenclature Consider the molecule 2-hexanol. How many carbons in the main chain? Saturated or unsaturated? What functional group? Consider the molecule octanoic acid. How many carbons in the main chain? Saturated or unsaturated? What functional group? Consider the molecule 4-methyl-2-pentanamine. How many carbons in the main chain? Saturated or unsaturated? What functional group? What is 4-methyl?

Substituents Groups off of main chain (branches) Parts of larger compounds (not stable by themselves) Alkyl groups = Alkane – H “-ane” changes to “-yl” Methyl methane – H CH 4 – H CH 3 ─ Ethyl ethane – H CH 3 CH 3 – H CH 3 CH 2 ─

Substituents Propane – H gives two possible alkyl groups Propyl Isopropyl Similarly, there are multiple alkyl groups with 4 carbon atoms, 5 carbon atoms, etc.

Alkyl groups you need to know Methyl Ethyl Propyl Isopropyl Butyl Isobutyl sec-butyl tert-butyl (t-butyl) Pentyl (amyl) Isopentyl (isoamyl) Neopentyl tert-pentyl Hexyl, heptyl, etc. Halogens Fluoro Chloro Bromo Iodo

Naming alkanes 1. Find the parent chain Longest continuous chain of C atoms Name of chain = parent name If 2 chains of equal length, parent is the chain with more substituents 2. Number each carbon in the parent chain Start from the end closest to the first substituent If there are substituents equal distance from both ends, number from the end nearest the second substituent

Naming alkanes, cont. 3. Name and number substituents Name = alkyl group name Number = point of attachment to parent chain Two substituents on the same C get the same number 4. Write the name as a single word Substituents before parent name (include #) Separate # and word with hyphen Separate two numbers with a comma List substituents in alphabetical order Multiple identical substituents use prefixes di, tri, tetra, penta, hexa DO NOT use sec, tert, di, tri, etc. when alphabetizing DO use iso, neo when alphabetizing

Examples StructureName

Examples Draw 3-ethylpentane. Draw all the constitutional isomers with the molecular formula C 6 H 14. Name each isomer.

Examples StructureName

Examples StructureName

Naming Cycloalkanes Unsubstituted cycloalkanes: Add “cyclo” to the parent name Bicycloalkanes Two rings Most common is norbornane Bicyclo[2.2.1]heptane

Naming Cycloalkanes Substituted cycloalkanes: Parent = ring or substituent (whichever has more carbons) Number the substituents Do not need to show number if only one substituent on a ring If two substituents, start with the first alphabetically, number in the direction of the second substituent If more than two substituents, number so that the substituents have the lowest set of numbers

Examples StructureName

Examples StructureName

Cycloalkane Stereoisomers Cycloalkanes are roughly planar Substituents are either above or below this plane Shown with dash and wedges Dash = back; wedge = forward In a disubstituted cycloalkane, two substituents on the same side (both back or both forward) are cis. Two substituents on opposite sides (one back, one forward) are trans. Cis and trans versions of the same molecule are stereoisomers Same molecular formula Same connectivity Different 3D orientation Cannot be converted by bond rotation

Examples StructureName Do these pairs represent constitutional isomers, cis- trans stereoisomers or the same compound? (a) (b)

Alkene Nomenclature Similar to alkanes Change infix from “-an-” to “-en-”

Naming Alkenes For larger alkenes: 1. Parent is longest C chain containing both carbons of C=C 2. Number chain so C=C has lowest possible number If the double bond is equidistant from both ends, start numbering at end nearest the first substituent Show location of C=C by first number Alkenes with >1 C=C use “-adiene”, “-atriene”, etc. in place of “-ene” and show location of all double bonds 3. Name and number substituents and write the full name Example:

Examples StructureName

StructureName Cycloalkenes The carbon atoms of the C=C are numbered 1 and 2 Number ring in direction to give first substituent lowest possible number

Alkene substituents SubstituentName CH 2 ═methylene CH 2 ═CH─vinyl CH 2 ═CH─CH 2 ─allyl

Alkene Stereoisomers Cis-trans stereoisomers Seen with disubstituted alkenes Cis means groups are on the same side of the double bond; trans means groups are on opposite sides Cannot convert through bond rotation Example: 2-butene

Examples Are the following alkenes cis, trans, or neither? (a) (b) (c)

Alkyne Nomenclature Similar to alkenes Change infix from “-en-” to “-yn-”

Naming Alkynes For larger alkynes: 1. Parent is longest C chain containing both carbons of C≡C 2. Number chain so C≡C has lowest possible number If the triple bond is equidistant from both ends, start numbering at end nearest the first substituent Show location of C≡C by first number Alkynes with >1 C≡C use “-adiyne”, “-atriyne”, etc. in place of “-yne” and show location of all double bonds 3. Name and number substituents and write the full name Example:

Enyne Contains both alkene and alkyne Number from end closest to first multiple bond (either C=C or C≡C) and show both numbers If the C=C and C≡C are equidistant from the ends, C=C gets the lower number Examples: StructureName

Naming Aromatic Compounds Benzene Monosubstituted benzenes Substituent name + “benzene”

Common Benzene Compounds

Benzene Nomenclature If substituent has greater than 6 carbons, it becomes the parent, and benzene is called a phenyl group Benzene substituents:

Disubstituted Benzenes ortho (1,2) meta (1,3) para (1,4)

Naming Disubstituted Benzenes If one substituent is part of a common name, that name is the parent and that substituent is at carbon 1 If neither substituent is part of a common name, list the substituents in alphabetical order (first alphabetically is at carbon 1) If both substituents are part of common name, use this order of priority to determine the parent name: -CO 2 H > -CHO > -OH > -NH 2 > -CH 3

Examples StructureName

Examples StructureName

Naming Polysubstituted Benzenes With 3 or more substituents do not use ortho, meta, para Number ring to give smallest set of numbers If a common name, use as parent (substituent at carbon 1) List substituents in alphabetical order

Examples StructureName

Another Aromatic Compound Pyridine If substituted, nitrogen is atom 1 of the ring. Number in direction of other substituents.

Naming Alcohols Acyclic alcohols 1. Parent chain is longest chain containing C bonded to –OH 2. Change suffix from “-e” to “-ol” 3. Number from end closest to –OH. Show location of –OH. 4. Name/number substituents Cyclic alcohols 1. Ring is the parent 2. Number ring so –OH is at carbon 1 and other substituents have lowest possible numbers. You do not need to show the location of the –OH. 3. Name/number substituents.

Naming Alcohols Multiple hydroxyl groups Two –OH groups is a diol; 3 is a triol Two adjacent –OH groups is a glycol Name as acyclic alcohols, except keep the “-e” suffix and add “-diol” Indicate numbers for all –OH groups Unsaturated alcohols (enol or ynol) 1. Parent chain contains carbon bonded to –OH and both carbons of C=C or C≡C 2. Suffix is “-ol”, infix is “-en-” or “-yn-” 3. Number chain so –OH has the lowest number 4. Show numbers for –OH and the unsaturation 5. Name/number substituents

Examples StructureName

Examples StructureName

Naming Thiols Thiols are sulfur analogs of alcohols Name like alcohols, but keep the “-e” and use “-thiol” in place of “-ol”

Naming Amines 1. Parent chain is longest containing C bonded to –N 2. Change suffix “-e” to “-amine” 3. Number from end closest to –N. Show location of –N. 4. Name/number substituents

Examples StructureName

Naming Aldehydes Parent chain contains carbon of CHO Suffix is “-al” CHO carbon is carbon 1 (do not need to show in name)

Naming Aldehydes Cyclic molecules with –CHO substituents -CHO is bonded to carbon 1 of ring Add “carbaldehyde” to end of ring parent name

Naming Ketones Parent chain contains carbon of carbonyl; suffix is “-one” Number so carbonyl has lowest number Cyclic ketones carbonyl is carbon 1 of the ring Some more common names:

Examples StructureName

Order of Precedence of Functions Used when more than one functional group in a molecule See Appendix in Klein Functional Group Suffix (High Precedence) Prefix (Low Precedence) -CO 2 H-oic acid- -CHO-alformyl- -C(O)--oneoxo- -OH-olhydroxy- -NH 2 -amineamino- Increasing precedence

Examples StructureName

Naming Carboxylic Acids Parent chain contains carbon of –CO 2 H Suffix is “-oic acid” –CO 2 H is carbon 1

Naming Carboxylic Acids Cyclic molecules with –CO 2 H substituents –CO 2 H is bonded to carbon 1 of ring Add “carboxylic acid” to end of ring parent name

Examples StructureName

Naming Acid Chlorides Name corresponding carboxylic acid Change “-ic acid” to “-yl chloride” Examples: StructureName

Naming Acid Anhydrides If R = R’, name carboxylic acid RCO 2 H. Replace “acid” with “anhydride” If R ≠ R’, list the two acids alphabetically and add the word “anhydride” Examples: StructureName

Naming Esters Name alkyl group bonded to oxygen (R’) Name carboxylic acid RCO 2 H Change “-ic acid” to “-ate” Examples: StructureName

Naming Amides Name corresponding carboxylic acid Change “-oic acid” to “-amide” Examples: StructureName

Example DMF (N,N-dimethylformamide) is a common solvent in organic chemistry. Draw the structure of DMF.

Naming Nitriles Two methods 1. Nitrile carbon is carbon 1 of parent chain. Add “-nitrile” to end of alkane name. 2. Name as carboxylic acid derivative. Replace “-ic acid” or “-oic acid” with “-onitrile”

Common Name System Can be used for some simple molecules Alkyl halides, alcohols, amines Name alkyl group Add “chloride” or “bromide” or “alcohol” or “amine” Examples: StructureName CH 3 Cl (CH 3 ) 2 CHBr CH 3 CH 2 OH CH 3 CH 2 NHCH 3 (CH 3 CH 2 ) 2 NH

Common Name System Ketones, ethers, sulfides Name both alkyl groups bonded to carbonyl (ketone), oxygen (ether), or sulfur (sulfide) Add “ketone” or “ether” or “sulfide” Examples: StructureName