OICC Press Iranian Journal of Catalysis 2345-4865 15 3 2025 09 30 Humic Acid: A Green Acid Catalyzed by Acylation of Amine, Phenol, and Thiols Derivatives under Solvent-Free Conditions 10.57647/j.ijc.2025.1503.36 EN Shripad Patil Lovely Professional University Ringgold standard institution, Chemistry Phagwara, India; Savitribai Phule Pune University Ringgold standard institution, Chemistry Karjat, India Atnv Sairaju Department of Engineering Chemistry, Andhra University, Visakhapatnam Hyderabad, India Abhishek Saxena Aragen Life Science Pvt. Ltd, Mallapur Hyderabad, India Nowduri Aannapurna Department of Engineering Chemistry, Andhra University, Visakhapatnam Hyderabad, India Journal Article 2025 09 30 Humic acid has been the catalyst in a novel process that effectively and environmentally acylates amine, phenol, and thiol derivatives. This method works well with aliphatic, aromatic, and heteroaromatic substrates, among other functionalized molecules. There is only one step involved in the simple method, which yields a high yield without any unintended side effects. In addition, the humic acid catalyst may be recycled at least four times, and the process is simpler, quicker, and greener than earlier research. The current work presented aniline (10 mmol, 0.93 mL), acetic anhydride (10 mmol, 1 mL), and humic acid catalyst (15 mg), which were stirred at room temperature for 10 minutes under solvent-free conditions to get a 97% yield. Highlights ·       A development of the protocol under Green methodology. ·       Acylation of phenol, amines, alcohol, and thiol derivatives under solvent-free condition. ·       Humic acid as a biodegradable catalyst. ·       After complete the reaction product was easily isolated from reaction mixture. ·       Humic acid is easily recyclable from reaction mixture.