Table 5.

General band assignments of the fourier transform infrared spectroscopy (FTIR) spectra of the hexane fraction of Kigelia africana fruit extract.

Characteristic Absorption (cm−1)	%T	Tentative Assignments
3700–3584	99.27	Alcohol, O–H Stretching, Medium-Sharp, Free
3550–3200	92.98	Alcohol, O–H Stretching, Strong, Broad, intermolecular bonded
3300–2500	82.92	Carboxylic acid, O–H Stretching, usually centred on 3000 cm−1
3000–2800	90.55	Amine Salt, N–H Stretching, Strong-Broad
2260–2222	98.29	Nitrile, CΞN stretching, Weak
2160–2120	98.06	Azide, N=N=N stretching, Strong
2065–2083	98.1	N=N anti symmetric stretch or C–N double bond or triple bond
1815–1785	97.97	C=O Stretching, S,
1750–1735	87.1	Esters, C=O Stretching, Strong, 6-membered lactone
1658–1648	88.85	Alkane, C=C stretching, Medium, vinylidene
1653–1624	88.79	C=O stretch in enol form
1639	88.07	N–H in primary amide or C=O β-Ketone of C=O stretch
1629	88	N–H in primary amide
1617	89.06	Vinyl carbon
1610	88.56	Vinyl carbon
1550–1500	94.41	N–O stretching
1508–1534	93.07	Benzene ring in aromatic compounds
1406–1404	82.02	C–N in primary amide
1420–1330	81.96	Alcohol, O–H Bending, Medium
1310–1250	81.26	Aromatic esters, C–O Esters
1342–1266	75.6	Aromatic amine, C–N Stretching
1250–1282	75.66	Ar-O in alky and aryl ethers
669,1124,1171, 1508, 1638	95	p-Coumaric acid
1172	74.82	C–OH in alcohols of C–O stretch
1099–1109	65.41	C–O–H in secondary and tertiary alcohols
1015–1022	51.74	CH–O–H in cyclic alcohols
1044	82.4	Ketone group
1086	95	Aromatic nucleus, C–H relation
905–936	74.22	Carbon ring in cyclic compounds
862–864	74.74	R-NH2 – in primary amine
761	67.76	CH2 out of plane
669	57.38	C–OH in alcohols of C–O–H bending
607	50.39	N–C=O in amides

FTIR = Fourier Transform Infrared Spectroscopy; %T = %Transmittance.