Functional groups

Nomenclature

The most important functional groups1. Carbon-carbon multiple bonds: double and triple bond

2. Compounds containing heteroatom, oxidation level of carbon: +1

3. Compounds containing heteroatom, oxidation level of carbon: +2 – aldehydes, ketones

4. Compounds containing heteroatom, oxidation level of carbon: +3 – carboxylic acid derivetives

5. Compounds containing heteroatom, oxidation level of carbon: +4 – carbonic acid derivatives

The most important functional groups 2.

This purpose requires a system of principles and rules, the application of which gives rise to a systematic nomenclature. Of course, a wide range of traditional names, semisystematic or trivial, are also in use for a core group of common compounds. Detailing the latest rules and international practice, this new volume can be considered a guide to the essential organic chemical nomenclature, commonly described as the “Blue Book”. An invaluable source of information for organic chemists everywhere and the definitive guide for scientists working in academia or industry, for scientific publishers of books, journals and databases, and for organisations requiring internationally approved nomenclature in a legal or regulatory environment.

NomenclatureChemical nomenclature is used to identify a chemical species by means of written or spokenwords and enables a common language for communication amongst chemists.Nomenclature for chemical compounds additionally contains an explicit or impliedrelationship to the structure of the compound, in order that the reader or listener can deducethe structure from the name.

IUPAC is the abbreviation of “International Union of Pure and Applied Chemistry

NomenclatureChemical nomenclature – unified system for namingBasic requirements: unambiguous, the structure is unambiguously reproducible on the basis of the name▪ one-by-one correspondence – one name belongs to only one structure,▪ one structure has one name (not always )▪ unambiguous description of constitution and configuration▪ the simplest and the shortest names▪ International and national nomenclatures – aim: the smallest difference

1st International convention – Genf (1892), Liege (1930), Luzern (1936), Rome (1938),„IUPAC” (1947), „Blue Book”

There are millions of organic compounds already known, and the list continues to grow!A system built on common names is not adequate to the task of communicating structuralinformation. Beginning in 1892, chemists developed a set of rules for naming organiccompounds based on their structures, which we now call the IUPAC rules, in whichIUPAC stands for the “International Union of Pure and Applied Chemistry.”

The most recent IUPAC rules for organic chemistry were published in 2013. The IUPAC rules often offer several different ways to name a single compound. Thusalthough it is true that no two compounds can have the same name, it is incorrect to believe that there is only a single IUPAC name for a particular compound.

Nomenclature

Types of nomenclatures:Common name/trivial name (origine, color…)

Semicommon name/semisystematic name (suffix (ending) reflect to the typical functionalgroup)

Nomenclature in organic chemistry is of two types: common (or “trivial”) and systematic.Some common names existed long before organic chemistry became an organizedbranch of chemical science.

Several alcohols are commonplace substances, well known by common names that reflecttheir origin (wood alcohol, grain alcohol) or use (rubbing alcohol).Wood alcohol is methanol (methyl alcohol, CH3OH), grain alcohol is ethanol (ethyl alcohol,CH3CH2OH), and rubbing alcohol is 2-propanol [isopropyl alcohol, (CH3)2CHOH].Glycerol (glycerin, propane-1,2,3-triol), glycol (ethylene glycol, ethane-1,2-diol).

Methane, ethane, propane, n-butane, isobutane, n-pentane are common names.

Systematic names – according to rulesBasic types: • Substitutive nomenclature: (most common): the highest priority functional group modifies

the suffix of the root (parent) name, while all other groups, or substituents, are added as prefixes to the root name.

• Functional class nomenclature: name of the compound based on the highest priority functional group, i.e. as an alcohol, ketone, alkyl halide, etc.

• Replacement : used to indicate when an atom, usually carbon, is replaced by another atom.

• Conjunctive : used to combine named subunits (i.e. cyclohexanecarboxylic acid).

Naming of hydrocarbons – it is a base for both nomenclature

Open chain saturated hydrocarbons – Greek numeral (except. C1-C4) + ane suffix

Open chain with double bond – unsaturated hydrocarbons –Greek numeral (except. C2-C4) + ene suffix. Locants (position),multiplier (di-, tri-, tetra-, penta-) Open chain with triple bond – unsaturated hydrocarbons –Greek numeral (except. C2-C4) + yne suffix. Locants (position),multiplier (di-, tri-, tetra-, penta-)

Nomenclature

Skeletalstructuralformula

The substituent is named in a similar way to the parent alkane, alkene, alkyne. It is named based on the number of carbon atoms in the branch (parent substituent) plus the suffix –yl by removing of one hydrogen.

– alkane alkyl– alkene alkenyl– alkyne alkynyl unsaturation is indicated in the suffix!

Cyclic hydrocarbones – cyclo prefix: cycloalkane, cycloalkene

Nomenclature

Abbreviations of alkyl groups:

methyl = Me, ethyl = Etpropyl = Pr, isopropyl = iPr

butyl = Bu, isobutyl = iBu, sec-butyl = sBu, tert-butyl = tBu

hexyl = Hx, cyclohexyl = cHx, allyl = All

Removing two or three hydrogens from the parent alkane:– alkane alkylidene (alkylidyn) – removing from the same C!

alternatives: alkane-1,1-diyl, alkane-1,1,1-triyl- alkane alkane-1,n-diyl – if H is removed from the first and from the n-th C!

Nomenclature

The structural formula of a chemical compound is a graphic representation of the molecular structure, showing how the atoms are arranged.ora chemical formula showing the linkage of the atoms in a molecule diagrammatically, as H–O–H(water molecule).

Structural formula

•In the condensed structural formula, each carbon atom is written separately and following each carbon atom are listed the other atoms that are bonded to that carbon atom (covalent bonds are not always shown).In this case the first carbon atom has three hydrogen atoms bonded to it, the second carbon atom has two hydrogen atoms bonded to it, the third carbon atom has two hydrogen atoms, and the fourth carbon atom has three hydrogen atoms. Another even more condensed way of writing a condensed structural formula is this. It points out that there are two CH2 groups in the middle of the molecule by having (CH2)2 in the middle of the formula.

The condensed formula for pentane is CH3(CH2)3CH3 or CH3CH2CH2CH2CH3 orCH3

_ CH2_ CH2

_ CH2_ CH3

An expanded structural formula is a structural formula that show all atoms in a molecule and all bonds connecting the atoms.

The expanded structural formula for pentane is

Structural formulas

The skeletal formula, also called line-angle formula or bond-line formula, of an organiccompound is a type of molecular structural formula that serves as a shorthand representation of a molecule's bonding and some details of its molecular geometry. A skeletal formula shows the skeletal structure or skeleton of a molecule, which is composed of the skeletal atoms that make up the molecule. It is represented in two dimensions, as on a page of paper. It employs certain conventions to represent carbon and hydrogen atoms, which are the most common in organic chemistry.The technique was developed by the organic chemist Friedrich August Kekulé von Stradonitz. Skeletal formulae have become ubiquitous in organic chemistry, partly because they are relatively quick and simple to draw. They can be thought of as abbreviated Lewis structures observing the following conventions: (1) carbon atoms are indicated as the terminus of a line segment or meeting point of line segments; (2) hydrogen atoms connected to carbon are omitted, with the presumption that each carbons atom is bonded to the number of hydrogen atoms that would bring its valence to 4 (or as close to satisfying the octet rule as other electronic details allow). As in a Lewis structure, a doubled or tripled line segment indicates double or triple bonding, respectively.

Skeletal formula

In contrast to a Lewis structure, however, only heteroatoms (atoms other than carbon or hydrogen) are explicitly shown, and non-bonding electron pairs are omitted.

The skeletal formula of the antidepressant drug escitalopram, featuring skeletal representations of heteroatoms, a triplebond, phenyl groups and stereochemistry

A chemical name typically has four parts in the IUPAC system of nomenclature: prefix, parent, locant, and suffix. The prefix identifies the various substituentgroups in the molecule, the parent selects a main part of the molecule and tellshow many carbon atoms are in that part, the locants give the positions of thefunctional groups and substituents, and the suffix identifies the primary functionalgroup.

Locant – Prefix – Parent – Suffix

What arethesubstituents?

Where are thesubstituentsand functionalgroups?

How manycarbons?

What is theprimaryfunctional group?

Principal Functional group •The principal functional group is used to define the class the compound belongs to e.g. an alcohol, ROH•The principal functional group is the highest priority functional group. Functional group priority is discussed later.•The principal functional group is usually given the lowest locantpossible.

Longest chain •The longest continuous chain containing the principal functional group defines the root name.•Other groups attached to this chain are called substituents.•If there are two chains of equal length, then the choice that gives the simplest substituents is chosen.

Numbering(i.e. assigning locants)

•The numbers that define the positions of the principal functional group and substituents are called locants.•Compounds are numbered from one end of the longest continuous chain.•The locants are assigned such that the principal functional group gets the lowest possible locant.•If this results in a "tie" then the first point of difference rule is applied so that the first time a difference in numbering occurs, then the method that gives the lower number at this first difference is used.•In the event that there is no first point of difference then alphabetisation is used.

Nomenclature

The IUPAC rules assign names to unbranched alkanes. Methane, ethane, propane, and butane are retained for CH4, CH3CH3, CH3CH2CH3, and CH3CH2CH2CH3, respectively. Thereafter, the number of carbon atoms in the chain is specified by a Latin or Greek prefix preceding the suffix -ane, which identifies the compound as a member of the alkane family. Notice that the prefix n- is not part of the IUPAC system. The IUPAC name for CH3CH2CH2CH3 is butane, not n-butane.

Naming of Alkanes

If there is more than one possibility, choose the chain that is more branched.

Find the longest continuous chain of carbons.

If there is more than one possibility, choose the chain that is more branched.

1 branch 2 branches

5 C

Choose this!

If there are substituents equal distance from either end, look for the next nearest branch to an end.

Number the chain beginning at the end of the nearest branch.

If there are substituents equal distance from either end, look for the next nearest branch to an end.

not from here

If there are different substituents equal distance from either end, look for the alphabetical order to number the chain.

beginning at the end nearer to ethyl substituent

Not 4-ethyl-3-methylhexane

Write the name for the molecule with groups listed alphabetically using prefixes (di, tri, tetra, penta, hexa, etc) to designate the number of each. Hyphens go between letters and numbers. Ignore all prefixes (except iso) when alphabetizing.

6-ethyl-3,4-dimethyloctane

Complex substituents - sometimes molecules have substituents (not part of the parent chain) that have additional branching. While there are some common names for 3- or 4-carbon complex side chains (e.g. Isobutyl), IUPAC has a systematic way of naming these groups as well. Basically, you follow similar rules as naming, but do it on a sub-part of the molecule. The main difference is that you always start numbering the side chain starting at the point of attachment as carbon number 1. Start at the point of attachment as number 1 and find the longest continuous carbon chain. This is the parent substituent. Number andname any branching groups according to this. All of the subname is enclosed in parentheses and placed into the full name of the molecule.

Alkanes can be joined at the ends to make ring compounds. In order to do this, twohydrogens must be lost. Thus, the general formula for cycloalkanes is CnH2n.

Cycloalkanes

Rule 1: Count the number of C's in the ring.(In the past! If greater than or equal to the largest substituent chain, the ring is the parent.If a substituent is larger, that is the parent)NOW (preferred IUPAC nomenclature): The ring gives the parent name of the compound!

Rule 2: for multi-substituted rings - start numbering at a point of attachment - number in the direction that gives the lowest numbers. Substituents are numbered according to their alphabetical priority - halogens included.

Bicyclic Structures (polycyclic ring systems)We name compounds containing two fused or bridged rings as bicycloalkanes. Use thename of the alkane corresponding to the total number of carbon atoms in the rings as theparent name. The carbon atoms common to both rings are called bridgeheads, and eachbond, or each chain of atoms, connecting the bridgehead atoms is called a bridge.

Use brackets to denote the number of carbon atoms in each bridge (in order of decreasinglength).

If substituents are present, number the bridged ring system beginning at one bridgehead,proceeding first along the longest bridge to the other bridgehead, then along the nextlongest bridge back to the first bridgehead. The shortest bridge is numbered last:

1

5

37

6

2

4

Bicyclic Structures

Spirocyclic compounds

Organic molecules in which one carbon atom is common to two rings are called spirocycliccompounds. (The simplest spirocyclic hydrocarbon is spiropentane, a productof laboratory synthesis. More complicated spirocyclic hydrocarbons not only have beensynthesized but also have been isolated from natural sources.)

Monospiro hydrocarbons with two monocyclic rings are named by the prefix spiro before a von Baeyer descriptor (indicating the numbers of carbon atoms linked to the spiro atom in each ring in ascending (rising) order and separated by a full stop) placed in square brackets and then the name of the parent hydrocarbon indicating the total number of skeletalatoms e.g. spiro[4.4]nonane.

Monospiro hydrocarbons with two monocyclic rings are numbered consecutively starting in the smaller ring at an atom next to the spiro atom, proceeding around the smaller ring back to the spiro atom and then round the second ring.

Spirocyclic compoundsMore examples

Double bonds in hydrocarbons are indicated by replacing the suffix -ane with -ene. If there is more than one double bond, the suffix is expanded to include a prefix that indicates the number of double bonds present (-adiene, -atriene, etc.). Triple bonds are named in a similar way using the suffix -yne. The position of the multiple bond(s) within the parent chain is(are) indicated by placing the number(s) of the first carbon of the multiple bond(s) directly in front of the base name.Here is an important list of rules to follow:

Rule 1: The longest chain is the main chain (seniority of chain length to degree of unsaturation)

Alkenes and Alkynes – unsaturated hydrocarbons

Rule 2: If there is more than one possibility, choose the chain that contains the most number of multiple bonds

Rule 3: The parent chain is numbered so that the multiple bonds have the lowest numbers (double and triple bonds have priority over alkyl and halo substituents)

Rule 4: When both double and triple bonds are present, numbers as low as possible are given to double and triple bonds even though this may at times give "-yne" a lower number than "-ene". When there is a choice in numbering, the double bonds are given the lowest numbers.

When both double and triple bonds are present, the -en suffix follows the parent chain directly and the -yne suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the location of the triple bond(s) is(are) indicated between the -en and -yne suffixes.

1

11

1

1 1

1 1

Cycloalkenes

Cycloalkenes and their derivatives are named by adapting cycloalkane terminology to the principles of alkene nomenclature.

No locants are needed in the absence of substituents; it is understood that the doublebond connects C-1 and C-2. Substituted cycloalkenes are numbered beginning with the double bond, proceeding through it, and continuing in sequence around the ring. The direction of numbering is chosen so as to give the lower of two possible locants to the substituent.

The list of important functional groups arranged in decreasing priority

order

Carboxylic Acids>Acid Anhydrides>Esters>Acyl Halides>

Amides>Nitriles>Aldehydes>Ketones>Alcohols>Thiols>Amines>Ethers>

Sulphides>Alkenes>Alkynes>Alkyl Halides>Nitro>Alkanes.

Functional group priority: The principal functional group is the highest priority functional group. The principal functional group is usually given the lowest locant possible.

Nomenclature

1. Acids (in the order COOH, C(O)O2H; then their S and Se derivatives, followed by sulfonic, sulfinic, selenonic, etc., phosphonic, arsonic, etc., acids)2. Anhydrides3. Esters4. Acid halides5. Amides6. Hydrazides7. Imides8. Nitriles9. Aldehydes, followed by thioaldehydes & selenoaldehydes10. Ketones, followed by thioketones & selenoketones11. Alcohols and Phenols, followed by thiols & selenols12. Hydroperoxides, followed by thiohydroperoxides & selenohydroperoxides13. Amines14. Imines15. Hydrazines, Phosphanes, etc.16. Ethers followed by sulfides & selenides17. Peroxides, followed by disulfides & diselenides

Nomenclature

Group Prefix

-Br Bromo-

-Cl Chloro-

-F Fluoro

-I Iodo-

=N2 Diazo-

-N3 Azido-

-NO Nitrozo-

-NO2 Nitro-

-OR alkyloxy-

-SR Alkylsulphanyl-

Choosing the main chain: saturated hydrocarbons: The longest continuous chain containing theprincipal functional group defines the root namePosition of substituents: • The locants are assigned such that the principal functional group gets the lowest possible

locant. • If this results in a "tie" then the first point of difference rule is applied so that the first

time a difference in numbering occurs, then the method that gives the lower number at this first difference is used.

• In the event that there is no first point of difference then alphabetisation is used.

Choosing the main chain: unsaturated hydrocarbonschain that contains the most number of multiple bondsif same number of multiple bonds can be found

• the longest chain is the main chain (root)• chain with more multiple bonds

If a double bond and a hydrocarbon group has the same position the double bond has got priority

Complex names e.g. 1,1-dimethylethyl must be written in brakets.If a group occurs more than once, a simple multiplier (e.g. di, tri, tetra, etc.) is used to indicate how many times it occurs.

Nomenclature

Functional Class General Formula Group Name (Prefix) Suffix

Alcoholates -O(-) oxido- -olate

Alcohols -O-H hydroxy- -ol

Ethers -OR (R)-oxy- ---

Peroxides -O-OR (R)-peroxy- ---

Thiols -SH mercapto-/sulfhydryl- -thiol

Sulfides -SR (R)-sulfanyl- ---

Amines -NH2 amino- -amine

Carboxylic acids -CO2H carboxy- -carboxylic acid

--- -oic acid

Carboxylate Salts -CO2(-) M(+) --- (cation) ...carboxylate

--- (cation) ...oate

Acid Halides -CO-X halocarbonyl- -carbonyl halide

--- -oyl halide

Amides -CONH2 carbamoyl- -carboxamide/amide

Esters(of carboxylic acids)

-COOR (R)-oxycarbonyl----

(R)...carboxylate(R)...oate

Hydroperoxides -O-OH hydroperoxy- ---

Aldehydes -CH=O formyl- -carbaldehyde

--- -al

Ketones C=O oxo- -one

Imines C=NR (R)-imino- -imine

Nitriles -C≡N cyano- -carbonitrile

--- -nitrile

Sulfonic acid -SO2H sulfo- -sulfonic acid