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An efficient method for the synthesis of N-(4-halophenacyl)-2-substituted-benzo[d]imidazoles using PEG-400 as green reaction solvent Konda, Shankaraiah Jore, Sanket Jeughale, Rupali Nagre, Sadashiv PEG-400 Green method Aromatic aldehydes o-Phenylenediamine 4-Halophenacylbromide N-Substituted benzimidazoles In this paper, we report a green and efficient method for the synthesis of N-substituted benzimidazoles under grinding conditions using PEG-400 as reaction solvent at room temperature. 2-Substituted-1H-benzimidazole was prepared from the reaction between various aromatic aldehydes and o-phenylenediamine in mortar and pestle under a grinding process using NH4Cl as catalyst in PEG-400 as green reaction solvent. Additionally, 2-substituted-1H- benzimidazole were treated with 4-halophenacylbromide in the K2CO3 / PEG system, yielding the corresponding 1-(4-fluoro/bromophenacyl)-2-susbtituted-benzo[d]imidazole (N-substituted benzimidazoles). This methodology incorporates inexpensive catalysts, suppressed reaction times, high yields, easy work-up, and the use of green reaction solvents are reported. All of the structures of products were established by spectroscopic and analytical methods. The IR spectra of 2-substituted-1H-benzimidazole (2a-e) showed the disappearance of the stretching frequency band at 1680-1695 cm-1 due to >C=O of aromatic aldehydes and the presence of stretching bands at 1610-1630 cm-1 due to -C=N stretching, which confirms the formation products. Furthermore, 1H NMR spectra of N-substituted benzimidazoles (4a-j) showed the presence of a singlet at δ 6.10-6.25 ppm, indicating the presence of -CH2 in the structure of the phenacyl ring. The mass spectra (EIMS) of the compounds also agree with their molecular formula. Atlanta Publishing House LLC 2026-06-30 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/2771 10.5155/eurjchem.17.2.155-160.2771 European Journal of Chemistry; Vol. 17 No. 2 (2026): June 2026; 155-160 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/2771/3038 Copyright (c) 2026 Shankaraiah Konda, Sanket Jore, Rupali Jeughale, Sadashiv Nagre https://creativecommons.org/licenses/by-nc/4.0