The optimal ratio of terephthalic acid to ethylene glycol for the synthesis of polyethylene terephthalate PET is 1:1, as it is a condensation polymerization reaction where one molecule of terephthalic acid reacts with one molecule of ethylene glycol to form the polymer.However, to achieve a high molecular weight polymer and ensure complete reaction, a slight excess of ethylene glycol 1-2% is often used. This helps to drive the reaction to completion and achieve a higher yield of PET.The best reaction conditions for the synthesis of PET are:1. Temperature: The reaction is typically carried out in two stages. In the first stage, esterification occurs at temperatures between 240-260C. In the second stage, polycondensation takes place at temperatures between 270-290C under vacuum.2. Catalysts: Catalysts are used to speed up the reaction and improve the yield. Commonly used catalysts include antimony trioxide Sb2O3 , titanium IV isopropoxide Ti OiPr 4 , and germanium dioxide GeO2 .3. Pressure: The esterification stage is carried out at atmospheric pressure, while the polycondensation stage is performed under vacuum around 0.1-1.0 mmHg to remove the byproduct, ethylene glycol, and drive the reaction to completion.4. Time: The reaction time depends on the specific process and equipment used, but it generally takes several hours to complete both stages of the reaction.By optimizing these reaction conditions, it is possible to achieve a high yield of polyethylene terephthalate in the synthesis process.