Research For Aromatic C-O Bonds Cleavage

Compounds containing aromatic C-O bonds such as phenols, esters, ethers innature and industrial production, and in the field of organic synthesis extensive exist. Itis common structure unit in the natural products and pharmaceutical chemistry forcompounds containing aromatic C-O bonds. Lignin of plants is a three-dimensional,highly branched, polyphenol compound containing an array of hydroxysubstituted andmethoxysubstituted phenylpropane units.Given aromatic C-O bonds of compoundsextensivly exist in the nature world and industrial production, the research forcleavaging aromatic C-O bonds in compounds especially cleavaging aromatic C-Obonds of the lignin is very important and significant.In study, cleavage aromatic C-O bonds in compounds has achived using Ni（acac）₃or Fe（acac）₃as catalyst, LiAlH4as reductant reagent, and t-BuONa as base under thecondition of not adding ligands. The main contents of this thesis are descrived asfollows:1. In this research, cleavage aromatic C-O bonds of different kinds of compoundswith2.5equivalents of Lithium Aluminum Hydride,2.5equivalents of sodium tert-butoxide,20mol%nickel acetylacetonate in2mL toluene was taken place after20hours of heat at140degrees Celsius under nitrogen environment. Under theconditions,aromatic C-O bonds of different compounds（14） were ruptured gettingcorresponding simple aromatics and alkanes. Besides of4-amino diphenyl ether,corresponding products from cleavage aromatic C-O bonds of diaryl ether GC internalstandard yield reached60-100%. Aryl alkyl ether and benzo heterocyclic containingaromatic C-O bonds can also be achieved cleavage aromatic C-O bonds of them butusually have poor result than that of diaryl ether.2. Based on the above results, we found that Compounds containing aromatic C-Obonds can undertake cleavage aromatic C-O bonds under the condition of Fe（acac）₃ascatalyst. considering the reaction temperature, reaction time, ligands, inorganic alkali,the amount of catalyst study on the reaction effect, the best reaction conditions is that 20mol%ferric acetylacetonate2.5equivalents of Lithium Aluminum Hydride,2.5equivalents of sodium tert-butoxide in1.5mL toluene was taken place after24hoursheating at140degrees Celsius under nitrogen environment. Under the condition,aromatic C-O bonds of different compounds（11） were ruptured getting correspondingproducts and the best GC internal standard yield and isolated yield could reach to100%and88%.