Study On The Synthetic Process Of Several Aromatic Aldehyde

After studying a variety kinds of synthesis of aromatic aldehydes, we finallydecided to synthesis3,4-dimethylbenzaldehyde,2,4-dimethybenzaldehyde,4-methylbenzaldehyde and o-phthalaldehyde by two different ways.3,4-dimethylbenzaldehyde,2,4-dimethybenzaldehyde and4-methylbenzalde-hyde were synthesized by Gattermann-Koch reaction under normal pressure with ahigh product yield and purity. The reaction pressure reduced from the high pressuremethod of1.37~4.11Mpa to atmospheric pressure. We proposed and validated thatthrough Gattermann-Koch reaction under normal pressure to synthesis3,4-dimethylbenzaldehyde,2,4-dimethylbenzaldehyde and4-methylbenzaldehydedidn’t require the addition of cocatalyst Cu2Cl2. The synthesis process conditionswere studied on the effect of catalyst dosage, reaction temperature and reaction timeon the yield of product. Under normal pressure, synthesizing these products reducedthe requirement on the equipment and improved the safety of the production process.It was suitable for industrial production with a good industrial value.We designed the route of synthesis of o-phthalaldehyde by1,2-Bis(chloromethyl)-benzene as the raw material. O-phthalaldehyde wassynthesized by nucleophilic substitution reaction, hydrolysis reaction and oxidationreaction. Firstly,1,2-Benzenedimethanol diacetate was synthesized by1,2-Bis(chloromethyl)benzene and sodium acetate anhydrous through nucleophilicreaction. Then,1,2-Benzenedimethanol was synthesized by1,2-Benzenedimethanoldiacetate through hydrolysis reaction. Thereby it eliminated the amplification effectof1,2-Bis(chloromethyl)benzene direct hydrolysis to1,2-Benzenedimethanol.Through experiment, we verified the feasibility of the route and successfullysynthesized the o-phthalaldehyde and studied on the effect of oxidation reagents,reaction temperature and reaction time on the yield of o-phthalaldehyde. The purity of products were determined by GC or HPLC and the structure ofproducts were confirmed by1H NMR and GC-MS.