Read the passage carefully and answer the questions.
Amines are considered as derivatives of ammonia obtained by replacement of hydrogen atoms with alkyl or aryl groups. In nature they occur among proteins, vitamins, alkaloids and hormones. These can be primary, secondary or tertiary depending on the number of hydrogen groups replaced. They can be prepared from nitro compounds, alkyl halides, nitriles, amides etc. Due to unshared pair of electrons they behave as Lewis bases. Influence of the number of hydrogen atoms at nitrogen atom is displayed in physical properties such as solubility, boiling point and chemical reactions including basicity. Basic character of amines is expressed in terms of their \( K_b \) and \( pK_b \) values. Three classes of amines can be distinguished with p-toluene sulphonyl chloride which reacts with primary and secondary amines. Amino group when attached to benzene ring behaves as an activating and ortho para directing group.
Give the IUPAC name of the compound
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 3,4-Dibromoaniline
An arylamine is named as a derivative of aniline (benzenamine), which is an accepted IUPAC name. The carbon atom carrying the –\( \ce{NH2} \) group is always C-1, and the ring is numbered in the direction that gives the lowest locants to the other substituents.
In the given compound, numbering from the carbon bearing –\( \ce{NH2} \) towards the bromine atoms puts them at C-3 and C-4 (the other direction would give 4 and 5). The two bromines are written with the prefix di-, so the name is 3,4-dibromoaniline (3,4-dibromobenzenamine).
NCERT (2026-27 edition):
Nomenclature – “… In arylamines, –\( \ce{NH2} \) group is directly attached to the benzene ring. \( \ce{C6H5NH2} \) is the simplest example of arylamine. In common system, it is known as aniline. It is also an accepted IUPAC name. While naming arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by ‘amine’. Thus in IUPAC system, \( \ce{C6H5-NH2} \) is named as benzenamine.”