Distinguishing between ortho, meta, and para isomers of monosubstituted aromatic compounds can be challenging, as they often have similar physical properties. However, you can use a combination of chemical tests and spectroscopic techniques to differentiate between them. Here are some methods:1. Nitration Test: Perform a nitration reaction on the monosubstituted aromatic compound using a mixture of concentrated nitric acid HNO3 and concentrated sulfuric acid H2SO4 . The ortho and para isomers will react more quickly than the meta isomer due to the activating effect of the substituent on the aromatic ring. The ortho and para isomers will form dinitro products, while the meta isomer will form a mononitro product. You can then separate and analyze the products using thin-layer chromatography TLC or column chromatography.2. Bromination Test: Carry out a bromination reaction using bromine Br2 in the presence of a Lewis acid catalyst, such as aluminum bromide AlBr3 or iron III bromide FeBr3 . The ortho and para isomers will react more readily than the meta isomer due to the activating effect of the substituent on the aromatic ring. The ortho and para isomers will form dibromo products, while the meta isomer will form a monobromo product. You can then separate and analyze the products using TLC or column chromatography.3. Infrared IR Spectroscopy: Analyze the monosubstituted aromatic compounds using IR spectroscopy. The ortho isomer will often display a characteristic out-of-plane C-H bending vibration at around 735-770 cm-1, which is absent in the meta and para isomers. The meta and para isomers can be differentiated by comparing their other IR absorption bands, such as the C-H in-plane bending vibrations and the C=C stretching vibrations.4. Nuclear Magnetic Resonance NMR Spectroscopy: Analyze the monosubstituted aromatic compounds using proton 1H and/or carbon 13C NMR spectroscopy. The ortho, meta, and para isomers will display different chemical shift patterns for their aromatic protons and carbons due to the different electronic environments created by the substituent. By comparing the chemical shifts and coupling constants, you can differentiate between the isomers.5. X-ray Crystallography: If you can obtain single crystals of the monosubstituted aromatic compounds, you can use X-ray crystallography to determine their molecular structures. This method will provide definitive information about the positions of the substituents in the aromatic ring, allowing you to distinguish between the ortho, meta, and para isomers.In summary, a combination of chemical tests and spectroscopic techniques can be used to differentiate between ortho, meta, and para isomers of monosubstituted aromatic compounds. It is essential to consider the specific substituent and the compound's reactivity when selecting the appropriate tests and techniques.