▎ 摘　　要

NOVELTY - Alkylation of alcohols by involving homogeneous/heterogeneous metal catalysts based on phosphine-free NNN pincer-group (VIII) chiral and achiral metal catalysts preferably phosphine-free NNN pincer-ruthenium carbonyl complexes (2a-2f) with high recyclability and turnovers involves adding catalytic amounts of the base to the group (VIII) pincer-metal catalyst in low molecular weight alcohol preferably ethanol to provide for a reaction mixture, heating the reaction mixture obtained at a predefined temperature of 60-200° C under an argon atmosphere, monitoring the heated reaction mixture with time spanning from 0.5-72 hours for the formation and obtaining higher molecular weight alkylated alcohol preferably butanol with high selectivity of 60-98% and in high total turnover numbers (TONs) in the range of 60-2100 and yields of 20-80% and adapted for up-gradation of alcohols including aliphatic alcohol preferably ethanol to biofuels. USE - Method for alkylation of alcohols using phosphine-free pincer-group chiral and achiral metal catalysts. ADVANTAGE - The method has environmentally friendly and trans-forms highly abundant alcohols to versatile raw materials, fuel, and commodity chemicals. The method is cheaper and highly efficient and provides a selective, recyclable, and cost-effective approach to versatile raw-material butanol (or higher molecular weight alcohol) with high yields as it does not use expensive or hazardous catalysts. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: a phosphine-free NNN pincer-group (VIII) has chiral and achiral metal catalysts having structure of formula (I) and (II), which comprises bis(imino)- pyridine or 2,6-bis(benzimidazole-2-yl) pyridine ligands preferably phosphine-free NNN pincer-ruthenium carbonyl complex based catalysts having structure of formulae (2a-2f); and a method for preparing phosphine-free NNN pincer-group (VIII) chiral and achiral metal catalysts, which involves taking specific ligand selected from bis(imino)pyridine, 2,6-bis(benzimidazole-2-yl) pyridine ligands (3a-f) and RuCl2(p-Cymene)2/OsCl3 in 2:1 in solvent preferably dry tetrahydrofuran (THF) in inert atmosphere, heating the reaction mixture at 60° C for 2hours under argon atmosphere, heating further for another 10 hours under carbon monoxide atmosphere while the color of the reaction mixture changed from brown to dark greenish brown, and evaporating solvent to yield a dark green color solid followed by washing in dry diethyl ether and hexane to afford the complex suitable as catalyst in yields of 74-88%. M=Fe,Ru,Os;R=Cy,Ph,i r,t u and chiral ligands;R =Me,Et;Y =PPh ,CH CN,CO; and Z =-OH,-COOH,-OMe,-NO ,-COOR,-NH ,Ph,Aryl,-C H ,-C h ,-SiOMe .