CHAPTER 18: Unit 2. Amines and Amides Types and Naming

Amines and Amides Types and Naming

Amines Types:

Depending on the replacement of hydrogen of ammonia, one can differentiate between primary amines 1o (replacement of one hydrogen atom), secondary amines 2o (replacement of two hydrogen atoms) and tertiary amines 3o (replacement of all three hydrogen atoms).

The fourth type of amine is called quaternary amines (ammonium cation where the hydrogen atoms are replaced by alkyl or aromatic phenyl groups). quaternary amines are salts with positive quaternary cation and anions such as halides etc.

quaternary amines (ammonium cation (positively charged))

If the organic groups R are alkyl group, the amines are said to be aliphatic amines If the organic groups R are aromatic groups such as phenyl groups, the amines are said to be aromatic amines organic groups R are cyclic ring groups, the amines are said to be cyclic amines.

Amides Types:

Reference: http://organicchemistrystructures.weebly.com/ketones-amines-and-amides.html

Amines and Amides Naming:

IUPAC Naming of Amines:The IUPAC naming of the amines is based on alkanes IUPAC names with omitting the last e alphabet of the alkanes And replace it with amine.Example: Primary 10 amines:CH3-NH2 is named as methane amine -> MethanamineThe common name ends as amine as well, but it has to specify the alkyl group name: MethylamineCH3-CH2-CH2- NH2 is named as propane amine -> 1 – PropanamineThe common name ends as amine as well, but it has to specify the alkyl group name: PropylamineThe numbering of carbon atom will depend on the location of the amino group NH2 at this carbon atom.

2 – propanamine (IUPAC name)Isopropylamine (Common name)For the structure above, which is the correct IUPAC name? 2 – propanamine or 2 – aminopropaneTo answer this question, one should refer oneself to the functional groups’ propriety naming shown below:

Reference: https://www.quora.com/What-is-the-priority-rank-of-groups-in-IUPAC-nomenclature

The amines take higher priority than the alkanes and hence the correct name for the above structure is: 2 – Propanamine.Example: Secondary 20 and Tertiary 3o amines:

The longest chain of alkane should be determined first and then the alkyl group are designated with alphabet N in front of each of them, The final naming will start with N’s alphabets of the alkyl groups (to emphasize their location at the amine nitrogen atom) and then with the long chain of alkane is named with omitted last alphabet e and the word amine is added at the end.

The longest chain is ethane connected to the nitrogen atom of the amine. This chain should be used. The shortest chain is methane connected to the nitrogen atom of the amineThe IUPAC name is: N – Methylethanamine (secondary amine) The common name is: Ethyl-Methylamine

The longest chain is 3 – methyl pentane connected to the nitrogen atom of the amine. This chain should be used. The shortest chain is methane connected to the nitrogen atom of the amine Since there are two methyl groups connected to nitrogen atom of the amine, two N,N alphabets should be used.The IUPAC name is: N,N – dimethyl – 3 – methylpentanamine The common name is: Dimethyl- isohexylamine

Example: Quaternary amines:

IUPAC name is: Tetra methyl ammonium chloride written without spacing: Tetramethylammonium chloride (it is a salt) The common name is the same as the IUPAC name: Tetramethylammonium chloride

Example: Aromatic amines:Aniline is approved by IUPAC to be used as the basis for the aromatic amines.

Benzamine (IUPAC name)

Aniline Aminobenzene and Phenylamine (common name and accepted IUPAC name as the basis of the aromatic amine.The amino group is connected to carbon atom is numbered 1. Other substituents will be attached to the aniline carbon atoms and should yield the lowest numbering (clockwise or counter clockwise).

Example of aromatic amines:

N,N Dimethylaniline (Tertiary aromatic amine)

N,N,N Trimethylanilinium chloride (Quaternary aromatic amine)

Aniline is converted to anilinium as a cation in the salt overall structure.

Example: Hetero cyclic amines:

Two types of the heterocyclic amines are adopted by IUPAC naming:

1.) 5 atom heterocyclic amines:

Reference: https://quizlet.com/23074656/chapter-183-heterocyclic-amines-and-alkaloids-flash-cards/

2) 6 atom heterocyclic amines:

Reference: https://quizlet.com/23074656/chapter-183-heterocyclic-amines-and-alkaloids-flash-cards/ Numbering of any substituents at any carbon atoms should yield the lowest numbering.

The videos below illustrate the naming of amines

The amines are depicted easier with the use of the Line – Angle Structures

The Line – Angle structures of amines are shown in the video below:

The figure below illustrates some examples of the line – angle structures of some amines:

Reference: https://www.ivyroses.com/Chemistry/Organic/How-to-draw-skeletal-formulae-of-organic-molecules.php

Example of Amides Line – Angle Structure:

Butanamide

Reference: http://www.chemspider.com/Chemical-Structure.10464.html

Amides Naming:

The videos below illustrate the naming of amindes:

Amide is made of a combination of carboxylic acid and amines:

Reference:https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_Chemistry_(OpenSTAX)/20%3A_Organic_Chemistry/20.4%3A_Amines_and_Amides

To name the amide, on has to name first the carboxylic acid. In this example we have 3 carbon atoms and the corresponding carboxylic acid is propanoic acid.The amide is called then propenamide according to the IUPAC nomenclature. The common name is propylamine

Example of amides:

Primary 1o amide:

2 – Bromoproanamide (IUPAC)

Secondary 2O amide:

N – Phyenlbutanamid (IUPAC)

Tertiary 3o amide:

N – Ethyl, N – methylbenzamid (IUPAC)