Answer :
Final answer:
An amide bond in IR spectroscopy appears in two significant absorption regions, with the Amide I band at approximately 1680 cm¹ and the Amide II band at 1620± 30 cm¹ for primary amides. Secondary amides show slightly lower frequencies. The correct frequency for an amide bond in IR spec is 1600-1700 cm¹. The correct option is A.
Explanation:
The frequency at which an amide bond appears in Infrared Spectroscopy (IR spec) typically includes two significant absorption regions. The Amide I band, characterized by C=O stretching, is usually observed at a higher frequency of approximately 1680 cm¹ for primary amides and slightly lower for secondary and tertiary amides.
The Amide II band is largely due to N-H bending and appears at 1620± 30 cm¹ for primary amides and 1530± 30 cm¹ for secondary amides.
Furthermore, the N-H stretching vibrations for primary amides typically exhibit two bands at 3170 to 3500 cm¹, whereas secondary amides show only one band near this region. Hence, the correct option for the frequency at which an amide bond appears in IR spec would be (a) 1600-1700 cm¹.
