IUPAC Nomenclature - Branched Chain Alkanes, Cyclic Compounds Unsaturated Compounds

The IUPAC (International Union of Pure and Applied Chemistry) nomenclature of organic chemistry is the standardized official naming rule of organic compounds, developed by the IUPAC. In this page we will discuss the IUPAC naming of alkanes, branched-chain alkanes, alkanes with substituents, and cycloalkanes.

In organic chemistry, a number of prefixes, suffixes and infixes are used to describe the type and position of functional groups in the compound.

The steps for naming an organic compound are as follows:

1. Identification of the parent hydrocarbon chain. This chain must obey the following rules, in order of precedence: It should have the maximum number of substituents of the suffix functional group. By suffix, it is meant that the parent functional group should have a suffix, unlike halogen substituents. If more than one functional group is present, the one with highest precedence should be used.

   • a) It should have the maximum number of multiple bonds.

   • b) It should have the maximum number of single bonds.

   • c) It should have the maximum length.

2. Identification of the parent functional group, if any, with the highest order of precedence.

3. Identification of the side-chains. Side chains are the carbon chains that are not in the parent chain, but are branched off from it.

4. Identification of the remaining functional groups, if any, and naming them by their ionic prefixes (such as hydroxy for -OH, oxy for =O, oxyalkane for O-R, etc.).

5. Different side-chains and functional groups will be grouped together in alphabetical order. (The prefixes di-, tri-, etc. are not taken into consideration for grouping alphabetically. For example, ethyl comes before dihydroxy or dimethyl, as the "e" in "ethyl" precedes the "h" in "dihydroxy" and the "m" in "dimethyl" alphabetically. The "di" is not considered in either case). When both side chains and secondary functional groups are present, they should be written mixed together in one group rather than in two separate groups.

6. Identification of double/triple bonds.

7. Numbering of the chain. This is done by first numbering the chain in both directions (left to right and right to left), and then choosing the numbering which follows these rules, in order of precedence.

   • a) Has the lowest-numbered locant (or locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached.

   • b) Has the lowest-numbered locants for multiple bonds (The locant of a multiple bond is the number of the adjacent carbon with a lower number).

   • c) Has the lowest-numbered locants for prefixes.

8. Numbering of the various substituents and bonds with their locants. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are (di – 2 tri – 3 tetra – 4 then as for the number of carbons below with 'a' added).

The numbers for that type of side chain will be grouped in ascending order and written before the name of the side-chain. If there are two side-chains with the same alpha carbon, the number will be written twice. Example: 2,2,3-trimethyl-. If there are both double bonds and triple bonds, "en" (double bond) is written before "yne" (triple bond). When the main functional group is a terminal functional group (a group which can only exist at the end of a chain, like formyl and carboxyl groups), there is no need to number it.

• (a) Arrangement in this form: Group of side chains and secondary functional groups with numbers made in step 3 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers. Wherever it says "with numbers," it is understood that between the word and the numbers, the prefix(di-, tri-) is used.

• (b) Adding of punctuation: Commas are put between numbers (236 should become 2,3,6). Hyphens are put between a number and a letter (236 trimethylheptane should become 2,3,6-trimethylheptane). Successive words are merged into one word (trimethyl heptane becomes trimethylheptane).

First one must memorize the names of straight-chain alkanes. Straight-chain alkanes are alkanes with one straight chain of carbon atoms, i.e. no branches.

\[\begin{array} &\text{# of Carbon atoms }(n)&&\text{IUPAC name}&&\text{Formula }(\text{C}_n\text{H}_{2n+2})\\ \hline\\ 1&&\text{Methane}&&\text{CH}_4\\ 2&&\text{Ethane}&&\text{C}_2\text{H}_6\\ 3&&\text{Propane}&&\text{C}_3\text{H}_8\\ 4&&\text{Butane}&&\text{C}_4\text{H}_{10}\\ 5&&\text{Pentane}&&\text{C}_5\text{H}_{12}\\ 6&&\text{Hexane}&&\text{C}_6\text{H}_{14}\\ 7&&\text{Heptane}&&\text{C}_7\text{H}_{16}\\ 8&&\text{Octane}&&\text{C}_8\text{H}_{18}\\ 9&&\text{Nonane}&&\text{C}_9\text{H}_{20}\\ 10&&\text{Decane}&&\text{C}_{10}\text{H}_{22}\\ 11&&\text{Undecane}&&\text{C}_{11}\text{H}_{24}\\ 12&&\text{Dodecane}&&\text{C}_{12}\text{H}_{26}\\ 13&&\text{Tridecane}&&\text{C}_{13}\text{H}_{28}\\ 20&&\text{Icosane}&&\text{C}_{20}\text{H}_{42} \end{array}\]

To name branched-chain alkanes, first the parent chain must be identified. The parent chain is the longest straight chain of carbon atoms within the compound.

In order to name organic compounds you must first memorize a few basic names. These names are listed within the discussion of naming alkanes. In general, the base part of the name reflects the number of carbons in what you have assigned to be the parent chain. The suffix of the name reflects the type(s) of functional group(s) present on (or within) the parent chain. Other groups which are attached to the parent chain are called substituents.

Alkanes - saturated hydrocarbons The names of the straight chain saturated hydrocarbons for up to a 12 carbon chain are shown below. The names of the substituents formed by the removal of one hydrogen from the end of the chain is obtained by changing the suffix -ane to -yl.

Number of Carbons Name 1 methane 2 ethane 3 propane 4 butane 5 pentane 6 hexane 7 heptane 8 octane 9 nonane 10 decane 11 undecane 12 dodecane There are a few common branched substituents which you should memorize. These are shown below.

Here is a simple list of rules to follow. Some examples are given at the end of the list.

Identify the longest carbon chain. This chain is called the parent chain.

Identify all of the substituents (groups appending from the parent chain).

Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When compairing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name.

If the same substituent occurs more than once, the location of each point on which the substituent occurs is given. In addition, the number of times the substituent group occurs is indicated by a prefix (di, tri, tetra, etc.).

If there are two or more different substituents they are listed in alphabetical order using the base name (ignore the prefixes). The only prefix which is used when putting the substituents in alphabetical order is iso as in isopropyl or isobutyl. The prefixes sec- and tert- are not used in determining alphabetical order except when compared with each other.

If chains of equal length are competing for selection as the parent chain, then the choice goes in series to: a) the chain which has the greatest number of side chains. b) the chain whose substituents have the lowest- numbers. c) the chain having the greatest number of carbon atoms in the smaller side chain. d)the chain having the least branched side chains.

A cyclic (ring) hydrocarbon is designated by the prefix cyclo- which appears directly in front of the base name.

In summary, the name of the compound is written out with the substituents in alphabetical order followed by the base name (derived from the number of carbons in the parent chain). Commas are used between numbers and dashes are used between letters and numbers. There are no spaces in the name.

Here are some examples:

Alkyl halides The halogen is treated as a substituent on an alkane chain. The halo- substituent is considered of equal rank with an alkyl substituent in the numbering of the parent chain. The halogens are represented as follows:

F fluoro- Cl chloro- Br bromo- I iodo- Here are some examples:

Alkenes and Alkynes - unsaturated hydrocarbons 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:

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).

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. See below for examples.

For a branched unsaturated acyclic hydrocarbon, the parent chain is the longest carbon chain that contains the maximum number of double and triple bonds. If there are two or more chains competing for selection as the parent chain (chain with the most multiple bonds), the choice goes to (1) the chain with the greatest number of carbon atoms, (2) the # of carbon atoms being equal, the chain containing the maximum number of double bonds.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Alcohols Alcohols are named by replacing the suffix -ane with -anol. If there is more than one hydroxyl group (-OH), the suffix is expanded to include a prefix that indicates the number of hydroxyl groups present (-anediol, -anetriol, etc.). The position of the hydroxyl group(s) on the parent chain is(are) indicated by placing the number(s) corresponding to the location(s) on the parent chain directly in front of the base name (same as alkenes).

Here is an important list of rules to follow:

The hydroxyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

When both double bonds and hydroxyl groups are present, the -en suffix follows the parent chain directly and the -ol 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 hydroxyl group(s) is(are) indicated between the -en and -ol suffixes. See below for examples. Again, the hydroxyl gets priority in the numbering of the parent chain.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Ethers You are only expected to know how to name ethers by their commmon names. The two alkyl groups attached to the oxygen are put in alphabetical order with spaces between the names and they are followed by the word ether. The prefix di- is used if both alkyl groups are the same.

Here are some examples:

Aldehydes Aldehydes are named by replacing the suffix -ane with -anal. If there is more than one -CHO group, the suffix is expanded to include a prefix that indicates the number of -CHO groups present (-anedial - there should not be more than 2 of these groups on the parent chain as they must occur at the ends). It is not necessary to indicate the position of the -CHO group because this group will be at the end of the parent chain and its carbon is automatically assigned as C-1.

Here is an important list of rules to follow:

The carbonyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

When both double bonds and carbonyl groups are present, the -en suffix follows the parent chain directly and the -al 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 -al suffix follows the -en suffix directly. Remember it is not necessary to specify the location of the carbonyl group because it will automatically be carbon #1. See below for examples. Again, the carbonyl gets priority in the numbering of the parent chain.

There are a couple of common names which are acceptable as IUPAC names. They are shown in the examples at the end of this list but at this point these names will not be accepted by the computer. Eventually they will be accepted.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Ketones Ketones are named by replacing the suffix -ane with -anone. If there is more than one carbonyl group (C=O), the suffix is expanded to include a prefix that indicates the number of carbonyl groups present (-anedione, -anetrione, etc.). The position of the carbonyl group(s) on the parent chain is(are) indicated by placing the number(s) corresponding to the location(s) on the parent chain directly in front of the base name (same as alkenes).

Here is an important list of rules to follow:

The carbonyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

When both double bonds and carbonyl groups are present, the -en suffix follows the parent chain directly and the -one 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 carbonyl group(s) is(are) indicated between the -en and -one suffixes. See below for examples. Again, the carbonyl gets priority in the numbering of the parent chain.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Carboxylic Acids Carboxylic acids are named by counting the number of carbons in the longest continuous chain including the carboxyl group and by replacing the suffix -ane of the corresponding alkane with -anoic acid. If there are two -COOH groups, the suffix is expanded to include a prefix that indicates the number of -COOH groups present (-anedioic acid - there should not be more than 2 of these groups on the parent chain as they must occur at the ends). It is not necessary to indicate the position of the -COOH group because this group will be at the end of the parent chain and its carbon is automatically assigned as C-1.

Here is an important list of rules to follow:

The carboxyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

If the carboxyl group is attached to a ring the parent ring is named and the suffix -carboxylic acid is added.

When both double bonds and carboxyl groups are present, the -en suffix follows the parent chain directly and the -oic acid 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 -oic acid suffix follows the -en suffix directly. Remember it is not necessary to specify the location of the carboxyl group because it will automatically be carbon #1. See below for examples. Again, the carboxyl gets priority in the numbering of the parent chain.

There are several common names which are acceptable as IUPAC names. They are shown in the examples at the end of this list but at this point these names will not be accepted by the computer. Eventually they will be accepted.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Esters Systematic names of esters are based on the name of the corresponding carboxylic acid. Remember esters look like this:

The alkyl group is named like a substituent using the -yl ending. This is followed by a space. The acyl portion of the name (what is left over) is named by replacing the -ic acid suffix of the corresponding carboxylic acid with -ate. Here are some examples:

Amines You are only expected to know how to name amines by their common names . They are named like ethers, the alkyl (R) groups attached to the nitrogen are put in alphabetical order with no spaces between the names and these are followed by the word amine. The prefixes di- and tri- are used if two or three of the alkyl groups are the same. NOTE: Some books put spaces between the parts of the name, but we will not. Follow the examples.

Here are some examples:

Summary of functional groups

Functional group Prefix Suffix carboxylic acids none -oic acid aldehydes none -al ketones none -one alchols hydroxy- -ol amines amino- -amine ethers alkoxy- -ether fluorine fluoro- none chlorine chloro- none bromine bromo- none iodine iodo- none -

\([proof text]( ||https://brilliant.org|| ||row 2 col 1||row 2 col 2||)\)

Many organic compounds found in nature or created in a laboratory contain rings of carbon atoms with distinguishing chemical properties; these compounds are known as cycloalkanes. Cycloalkanes only contain carbon-hydrogen bonds and carbon-carbon single bonds, but in cycloalkanes, the carbon atoms are joined in a ring. The smallest cycloalkane is cyclopropane.

Figure 1: The first four cycloalkanes

If you count the carbons and hydrogens, you will see that they no longer fit the general formula CnH2n+2CnH2n+2. By joining the carbon atoms in a ring,two hydrogen atoms have been lost. The general formula for a cycloalkane is CnH2nCnH2n. Cyclic compounds are not all flat molecules. All of the cycloalkanes, from cyclopentane upwards, exist as "puckered rings". Cyclohexane, for example, has a ring structure that looks like this:

Figure 2: This is known as the "chair" form of cyclohexane from its shape, which vaguely resembles a chair. Note: The cyclohexane molecule is constantly changing, with the atom on the left, which is currently pointing down, flipping up, and the atom on the right flipping down. During this process, another (slightly less stable) form of cyclohexane is formed known as the "boat" form. In this arrangement, both of these atoms are either pointing up or down at the same time

In addition to being saturated cyclic hydrocarbons, cycloalkanes may have multiple substituents or functional groups that further determine their unique chemical properties. The most common and useful cycloalkanes in organic chemistry are cyclopentane and cyclohexane, although other cycloalkanes varying in the number of carbons can be synthesized. Understanding cycloalkanes and their properties are crucial in that many of the biological processes that occur in most living things have cycloalkane-like structures.

drawing012.gif drawing013.gif
cholesterol.gif

Glucose (6 carbon sugar) Ribose (5 carbon sugar) Cholesterol (polycyclic)

Although polycyclic compounds are important, they are highly complex and typically have common names accepted by IUPAC. However, the common names do not generally follow the basic IUPAC nomenclature rules. The general formula of the cycloalkanes is CnH2nCnH2n where nn is the number of carbons. The naming of cycloalkanes follows a simple set of rules that are built upon the same basic steps in naming alkanes. Cyclic hydrocarbons have the prefix "cyclo-".

Parent Chains For simplicity, cycloalkane molecules can be drawn in the form of skeletal structures in which each intersection between two lines is assumed to have a carbon atom with its corresponding number of hydrogens.

2 (1).gif same as 4.gif same as cyclohexane.gif

Cycloalkane Molecular Formula Basic Structure Cyclopropane (C3H6\0 cyclopropane.gif Cyclobutane C4H8C4H8 cyclobutane.gif Cyclopentane C5H10C5H10 cyclopentane.gif Cyclohexane C6H12C6H12 cyclohexane.gif Cycloheptane C7H14C7H14 cycloheptane.gif Cyclooctane C8H16C8H16 cyclooctane.gif Cyclononane C9H18C9H18 cyclononane.gif Cyclodecane C10H20C10H20 cyclodecane.gif IUPAC Rules for Nomenclature Determine the cycloalkane to use as the parent chain. The parent chain is the one with the highest number of carbon atoms. If there are two cycloalkanes, use the cycloalkane with the higher number of carbons as the parent chain. If there is an alkyl straight chain that has a greater number of carbons than the cycloalkane, then the alkyl chain must be used as the primary parent chain. Cycloalkane acting as a substituent to an alkyl chain has an ending "-yl" and, therefore, must be named as a cycloalkyl.

Cycloalkane Cycloalkyl cyclopropane cyclopropyl cyclobutane cyclobutyl cyclopentane cyclopentyl cyclohexane cyclohexyl cycloheptane cycloheptyl cyclooctane cyclooctyl cyclononane cyclononanyl cyclodecane cyclodecanyl Example 1 drawing020.gif

The longest straight chain contains 10 carbons, compared with cyclopropane, which only contains 3 carbons. Because cyclopropane is a substituent, it would be named a cyclopropyl-substituted alkane.

Determine any functional groups or other alkyl groups. Number the carbons of the cycloalkane so that the carbons with functional groups or alkyl groups have the lowest possible number. A carbon with multiple substituents should have a lower number than a carbon with only one substituent or functional group. One way to make sure that the lowest number possible is assigned is to number the carbons so that when the numbers corresponding to the substituents are added, their sum is the lowest possible. drawing01 (2).gif(1+3=4) NOT drawing02 (4).gif(1+5=6)

When naming the cycloalkane, the substituents and functional groups must be placed in alphabetical order. noname20.gif drawing03.gif

(ex: 2-bromo-1-chloro-3-methylcyclopentane)

Indicate the carbon number with the functional group with the highest priority according to alphabetical order. A dash"-" must be placed between the numbers and the name of the substituent. After the carbon number and the dash, the name of the substituent can follow. When there is only one substituent on the parent chain, indicating the number of the carbon atoms with the substituent is not necessary. (ex: 1-chlorocyclohexane or cholorocyclohexane is acceptable) drawing3.gif

If there is more than one of the same functional group on one carbon, write the number of the carbon two, three, or four times, depending on how many of the same functional group is present on that carbon. The numbers must be separated by commas, and the name of the functional group that follows must be separated by a dash. When there are two of the same functional group, the name must have the prefix "di". When there are three of the same functional group, the name must have the prefix "tri". When there are four of the same functional group, the name must have the prefix "tetra". However, these prefixes cannot be used when determining the alphabetical priorities. There must always be commas between the numbers and the dashes that are between the numbers and the names. Example 2 drawing.gif noname21.gif

      (2-bromo-1,1-dimethylcyclohexane)

Notice that "f" of fluoro alphabetically precedes the "m" of methyl. Although "di" alphabetically precedes "f", it is not used in determining the alphabetical order.

Example 3 drawing07.gif

(2-fluoro-1,1,-dimethylcyclohexane NOT 1,1-dimethyl-2-fluorocyclohexane)

8) If the substituents of the cycloalkane are related by the cis or trans configuration, then indicate the configuration by placing "cis-" or "trans-" in front of the name of the structure.

3D2.gif

Blue=Carbon Yellow=Hydrogen Green=Chlorine

Notice that chlorine and the methyl group are both pointed in the same direction on the axis of the molecule; therefore, they are cis.

drawing13.gif cis-1-chloro-2-methylcyclopentane

9) After all the functional groups and substituents have been mentioned with their corresponding numbers, the name of the cycloalkane can follow.

Reactivity Cycloalkanes are very similar to the alkanes in reactivity, except for the very small ones, especially cyclopropane. Cyclopropane is significantly more reactive than what is expected because of the bond angles in the ring. Normally, when carbon forms four single bonds, the bond angles are approximately 109.5°. In cyclopropane, the bond angles are 60°.

With the electron pairs this close together, there is a significant amount of repulsion between the bonding pairs joining the carbon atoms, making the bonds easier to break.

Alcohol Substituents on Cycloalkanes Alcohol (-OH) substituents take the highest priority for carbon atom numbering in IUPAC nomenclature. The carbon atom with the alcohol substituent must be labeled as 1. Molecules containing an alcohol group have an ending "-ol", indicating the presence of an alcohol group. If there are two alcohol groups, the molecule will have a "di-" prefix before "-ol" (diol). If there are three alcohol groups, the molecule will have a "tri-" prefix before "-ol" (triol), etc.

Example 4 The alcohol substituent is given the lowest number even though the two methyl groups are on the same carbon atom and labeling 1 on that carbon atom would give the lowest possible numbers. Numbering the location of the alcohol substituent is unnecessary because the ending "-ol" indicates the presence of one alcohol group on carbon atom number 1.

drawing04.gif

2,2-dimethylcyclohexanol NOT 1,1-dimethyl-cyclohexane-2-ol

Example 5 drawing05.gif

3-bromo-2-methylcyclopentanol NOT 1-bromo-2-methyl-cyclopentane-2-ol

Example 6 noname30 (1).gif

Blue=Carbon Yellow=Hydrogen Red=Oxygen

  drawing06.giftrans-cyclohexane-1,2-diol

Other Substituents on Cycloalkanes There are many other functional groups like alcohol, which are later covered in an organic chemistry course, and they determine the ending name of a molecule. The naming of these functional groups will be explained in depth later as their chemical properties are explained.

Name Name ending alkene -ene alkyne -yne alcohol -ol ether -ether nitrile -nitrile amine -amine aldehyde -al ketone -one carboxylic acid -oic acid ester -oate amide -amide

Although alkynes determine the name ending of a molecule, alkyne as a substituent on a cycloalkane is not possible because alkynes are planar and would require that the carbon that is part of the ring form 5 bonds, giving the carbon atom a negative charge.

pz1.gif

However, a cycloalkane with a triple bond-containing substituent is possible if the triple bond is not directly attached to the ring.

Example 7 pz2.gif

ethynylcyclooctane

Example 8 drawing6.gif

1-propylcyclohexane

Summary Determine the parent chain: the parent chain contains the most carbon atoms. Number the substituents of the chain so that the sum of the numbers is the lowest possible. Name the substituents and place them in alphabetical order. If stereochemistry of the compound is shown, indicate the orientation as part of the nomenclature. Cyclic hydrocarbons have the prefix "cyclo-" and have an "-alkane" ending unless there is an alcohol substituent present. When an alcohol substituent is present, the molecule has an "-ol" ending. Glossary alcohol: An oxygen and hydrogenOH hydroxyl group that is bonded to a substituted alkyl group. alkyl: A structure that is formed when a hydrogen atom is removed from an alkane. cyclic: Chemical compounds arranged in the form of a ring or a closed chain form. cycloalkanes: Cyclic saturated hydrocarbons with a general formula of CnH(2n). Cycloalkanes are alkanes with carbon atoms attached in the form of a closed ring. functional groups: An atom or groups of atoms that substitute for a hydrogen atom in an organic compound, giving the compound unique chemical properties and determining its reactivity. hydrocarbon: A chemical compound containing only carbon and hydrogen atoms. saturated: All of the atoms that make up a compound are single bonded to the other atoms, with no double or triple bonds. skeletal structure: A simplified structure in which each intersection between two lines is assumed to have a carbon atom with its corresponding number of hydrogens. Problems Name the following structures. (Note: The structures are complex for practice purposes and may not be found in nature.)

1) cyclodecane.gif 2) drawing08.gif 3) drawing09.gif 4)drawing2.gif 5)drawing4.gif 6)drawing7.gif

7)drawing010.gif

Draw the following structures.

8) 1,1-dibromo-5-fluoro-3-butyl-7-methylcyclooctane 9) trans-1-bromo-2-chlorocyclopentane

10) 1,1-dibromo-2,3-dichloro-4-propylcyclobutane 11) 2-methyl-1-ethyl-1,3-dipropylcyclopentane 12) cycloheptane-1,3,5-triol

Name the following structures.

Blue=Carbon Yellow=Hydrogen Red=Oxygen Green=Chlorine

13)noname05 (1).gif 14)noname06.gif 15)noname07.gif 16)noname08.gif 17)noname09.gif

18)noname10.gif 19)noname11.gif

Answers to Practice Problems 1) cyclodecane 2) chlorocyclopentane or 1-chlorocyclopentane 3) trans-1-chloro-2-methylcycloheptane

4) 6-methyl-3-cyclopropyldecane 5) cyclopentylcyclodecane or 1-cyclopentylcyclodecane 6) 1,3-dibromo-1-chloro-2-fluorocycloheptane

7) 1-cyclobutyl-4-isopropylcyclohexane

8)drawing10.gif 9)drawing11.gif 10)drawing12.gif 11)drawing9.gif 12)drawing011.gif

13) cyclohexane 14) cyclohexanol 15) chlorocyclohexane 16) cyclopentylcyclohexane 17) 1-chloro-3-methylcyclobutane

18) 2,3-dimethylcyclohexanol 19) cis-1-propyl-2-methylcyclopentane