Module 4: Nomenclature of Organic Compounds Flashcards
Structural features that make it possible to classify compounds by reactivity
Functional Groups
A group of atoms within a larger molecule that has a characteristic chemical behavior.
Functional Groups
- With Carbon–Carbon Multiple Bonds
- C=C
Alkenes
- With Carbon–Carbon Multiple Bonds
- C=-C
Alkynes
- With Carbon Singly Bonded to an Electronegative Atom
= Alkyl halides
RX
- With Carbon–Carbon Multiple Bonds
- Aromatic (benzene) ring
Arenes
- With Carbon Singly Bonded to an Electronegative Atom
= Alcohols
ROH
- with a Carbon–Oxygen Double Bond (Carbonyl Groups)
= RCHO
Aldehydes
RNH2
Amines
- With Carbon–Carbon Multiple Bonds
- C-C
Alkanes
- With Carbon Singly Bonded to an Electronegative Atom
= Ethers
ROR
- With Carbon Singly Bonded to an Electronegative Atom
= Thiols
RSH
- With Carbon Singly Bonded to an Electronegative Atom
= Sulfides
RSR
RX
Alkyl halides
- With Carbon Singly Bonded to an Electronegative Atom
= Amines
RNH2
- with a Carbon–Oxygen Double Bond (Carbonyl Groups)
= RCOOR
Esters
RSH
Thiols
RSR
Sulfides
ROH
Alcohols
ROR
Ethers
Carboxylic acids
RCOOH
- with a Carbon–Oxygen Double Bond (Carbonyl Groups)
= RCOOH
Carboxylic acids
- with a Carbon–Oxygen Double Bond (Carbonyl Groups)
= RCONH2
Amides
- with a Carbon–Oxygen Double Bond (Carbonyl Groups)
= RCOR
Ketones
Ketones
RCOR
Esters
RCOOR
Common/ Trivial Names
IUPAC Nomenclature
Aldehydes
RCHO
Amides
RCONH2
Systematic Names
IUPAC Nomenclature
A system for naming organic compounds
International Union of Pure and Applied Chemistry or IUPAC (pronounced “eye-you-pack”) System
- are aliphatic HC
– Physical properties similar to animal fats and plant oil (Greek aleiphas, meaning “fat or oil”)
Alkanes
- are saturated HC
– Has the maximum number of H atoms
Alkanes
Naming Straight (unbranched) Chain Alkanes
- ends with “-ane”
- “Parent” – “ane”
(No. of Carbons)
-CH2- group is called?
methylene group
- General Formula:
Alkanes
CnH2n+2
What is the molecular formula of an alkane with six carbon atoms?
n=6
CnH2n+2
C6H2(6) +2
C6H14
Steps Naming Branched Chain Alkanes (Step 1)
STEP 1:
Find the parent hydrocarbon.
A. Find the longest continuous carbon chain.
– The longest chain may not always be obvious; you may have to “turn corners”:
B. If two chains of equal length are present, choose the one with the larger number of branch points as the parent.
Steps Naming Branched Chain Alkanes (Step 2)
STEP 2:
Number the atoms in the main chain.
*Begin at the end nearer the first branch point
Steps Naming Branched Chain Alkanes (Step 3)
STEP 3:
Identify and number the substituents.
- Assign a number to each substituent according to its point of attachment on the parent chain.
- If there are two substituents on the same carbon, assign them both the same number.
- There must always be as many numbers in the name as there are substituents.
Steps Naming Branched Chain Alkanes (Step 4)
STEP 4:
Write the name as a single word.
- Use hyphens to separate the various prefixes and commas to separate numbers.
- If two or more different side chains are present, cite them in alphabetical order.
- If two or more identical side chains are present, use one of the prefixes di-, tri-, tetra-, and so forth.
– Don’t use these prefixes for alphabetizing, though.
Other Notes:
* For historical reasons, a few simple branched-chain alkyl groups also have nonsystematic, common names
[3-Carbon alkyl group]
+ Isopropyl (i-Pr)
[4-Carbon alkyl groups]
+ sec-Butyl (sec-Bu)
+ Isobutyl
+ tert-Butyl (t-Butyl or t-Bu)
Other Notes:
* The prefixes di-, tri-, tetra-, and so on are not included in alphabetizing. Neither are the hyphenated prefixes sec-and tert-.
* “Iso,” as in isopropyl, is included in alphabetizing.
Additional Info
STEP 1 Name the parent hydrocarbon.
– Find the longest carbon chain that contains the double bond, and name the compound using the suffix -ene or -yne.
STEP 2 Number the carbon atoms in the chain.
– Begin numbering at the end nearer the double or triple bond. If the bond is equidistant from the two ends, begin numbering at the end nearer the first branch point.
STEP 3 Write the full name.
– Number the substituents according to their positions in the chain, and list them
alphabetically. Indicate the position of the bond by giving the number of the first
alkene carbon and placing that number directly before the -ene or -yne suffix.
Naming Alkenes and Alkynes
Find longest chain, name it as parent chain
– Number from end nearest any substituent
(alkyl or halogen)
- Naming if Two Halides or Alkyl Are Equally Distant from Ends of Chain
– Begin at the end nearer the substituent having its name first in the alphabet
Naming Alkyl Halides
- Select the longest carbon chain containing the hydroxyl group
– Derive the parent name by replacing the -e ending of the corresponding alkane with –ol.
- Select the longest carbon chain containing the hydroxyl group
– Derive the parent name by replacing the -e ending of the corresponding alkane with –ol. - Number the chain from the end nearer the hydroxyl group.
– Number substituents according to position on chain, listing the substituents in alphabetical order.
Naming Parent Chain with 2 Carbons
* Do not indicate the position number if it is UNAMBIGUOUS.
* Consider the name of;
– an alcohol with 2C.
* Ethanol NOT 1-ethanol
– an alkene with 2C.
* Ethen NOT 1-ethene
[NAMING ALCOHOLS]
Special Notes:
* If the parent is no more than 2C, numbering the functional group is not necessary.
* If one substituent is present, it should be assigned the lower possible number.
* When multiple substituents are present, assign numbers so that the first substituent receives the lower number.
* If there is a tie, then the second locant should be as low as possible
* If the previous rule does not break the tie, such as in the case below, then the lowest number should be assigned alphabetically
- Select the longest carbon chain as the parent alkane and name the -OR group bonded to it as an alkoxy substituent.
– Do not forget to number the substituent.
- List the alkyl groups bonded to oxygen in alphabetical order and add the word ether.
– Take note of the spacing.
[Naming Ethers]
- Select the parent alkane with the longest chain of carbon atoms that contains the –
SH group.
– Add –thiol to the name of the parent alkane. - Number the parent chain in the direction that gives the –SH group the lower number
Naming Thiols
- Named by rules used for ethers, with sulfide in place of ether for simple compounds and alkylthio in place of alkoxy.
- Named by rules used for ethers, with sulfide in place of ether for simple compounds and alkylthio in place of alkoxy.
Naming Thioethers/Sulfides
- 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.
– Position number is NOT indicated. - For aldehydes with complex substituents, numbering starts at –CHO.
Naming Aldehydes
- 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 (C=O).
Naming Ketones
- For open-chain alkanes, replace the terminal -e of the alkane name with -oic acid.
- The carboxyl carbon atom is C1.
- Similar to aldehydes
Naming Carboxylic acids
- Indicate the alkyl group attached to the oxygen atom.
- Indicate the carboxylic acid, for which the suffix “oic acid”
is replaced with “oate” (-ic acid -ate). With SPACES.
Naming Esters
- Depends on the complexity.
- Alkyl amines (simple)
– Alkyl substituent is identified followed by the suffix “amine“
– Similar to ether but no spaces
ethylamine
- Alkanamines (with more complex alkyl groups)
– Similar to alcohols -ol, -amine
ethanamine
2C parent -> position unnecessary
Naming Primary Amines
- Depends on the complexity.
- Alkyl amines
– groups are listed in alphabetical order
– Similar to ether but no spaces - Alkanamines
– Treat the longest chain as the parent
– Use the locant “N” to identify substituents connected to the nitrogen atom
Naming Secondary and Tertiary
Amines
- Substituted cycloalkanes are named by rules similar to those for open-chain alkanes. For most compounds, there are
only two steps:
STEP 1 Count the number of carbon atoms in the ring and the number in the largest
substituent chain.
* If ring > chain Parent = Ring
* If chain > ring Parent = Chain
- STEP 2 For substituted cycloalkanes, start at a
point of attachment and number around the ring.
– If two substituents are present, begin numbering at
the group that has alphabetical priority and proceed around the ring so as to give the second substituent the lowest number.
Naming Cycloalkanes
- Named in a similar way
- Number the cycloalkene so that the double bond
is between C1 and C2; - and so that the first substituent has as low a number as possible.
- Note that it’s not necessary to specify the position of the double bond in the name because it’s always between C1 and C2
- Aromatic was used to describe some fragrant compounds in the early 19th century
– Not correct: later they are grouped by chemical behavior
(unsaturated compounds that undergo substitution rather
than addition)
Naming Aromatic Compounds
- Monosubstituted Derivatives of Benzene
– “benzene” as parent
– substituents as prefix - 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—”
- Sometimes indicated with the letters Ar
– Presence of an aromatic ring - Disubstituted Derivatives of Benzene
- Relative positions on a benzene ring
– ortho- (o) on
adjacent carbons (1,2)
– meta- (m) separated
by one carbon (1,3)
– para- (p) separated
by two carbons (1,4)
Naming Aromatic Compounds
- Polysubstituted Derivatives of Benzene
– 1. Identify and name the parent.
– 2. Identify and name the substituents.
– 3. Assign a locant to each substituent.
– 4. Arrange the substituents alphabetically
- Monosubstituted Derivatives of Benzene
+ CH3 - Toluene
+ OH - Phenol
+ O - CH3 - Anisole
+ NH2 - Aniline
+ C = O - OH - Benzoic acid
+ C = O - H - Benzaldehyde
+ C = O - CH3 - Acetophenone
+ alkene - Styrene
Benzene OH
Phenol
Benzene C = O - OH
Benzoic Acid
Benzene CH3
Toluene
Benzene O - CH3
Anisole
Benzene NH2
Aniline
Benzene C = O - H
Benzaldehyde
Benzene C = O - CH3
Acetophenone
Benzene Alkene
Styrene
