Study On Synthesis Of Dichlorophenylphosphine(DCPP) By Ultrasound Irradiation

Dichlorophenylphosphine is an important monomer of organophosphoruscompound. It is also an intermediate to synthesize pesticides, plasticizer, nylonstabilizer, dye, paint adjuvant, anti-blowing agent, antioxidant, photopolymerizationevocating agent. The major preparations of DCPP included hot-tube process, autoclave process,electrically-heated fluid-bed reactor process and Friedel-Crafts process etc. Atpresent, domestic researchers mainly prepare DCPP through Friedel-Crafts process.The advantages of this method lie in available materials and relative safe operationalcondition. The main disadvantages are long reaction time, low yield and more wasteresidues, which are difficult to deal with. Ultrasound irradiation is remarkable to improve organic synthesis. It not only canincrease reaction rate, decrease reaction time, but also can carve out new reaction way.So sonochemistry is an active field in resent years, but there weren't any reportsconcerned synthesis DCPP by ultrasound. The influence parameters to synthesizing DCPP include time, material mole ratio,mass of catalyst and complexant, agitation speed and temperature etc. Orthogonalexperiment was designed on the basis of traditional agitation, finally obtained optimalreaction conditions are as follows: 4～5 hours; nC6H6:nPCl3:nAlCl3=1:3:1.1;nNaCl(180~200mesh): nAlCl3=1.6:1; 390r/min ; 72 ～ 76 ℃ . Materials ratio ismaximal influence parameter; the following in turns are time and mass of catalyst.The yield of DCPP was 89.2%, the purity was 99.7% under the conditions of optimalparameters. The flask was set into the ultrasound field emitted from a 40kHz purge-tankultrasound generator, and the effects of ultrasound pressure and reaction time on theyield of DCPP was studied. A conclusion was reached: under the condition of 4 hours,the yield of DCPP by additional ultrasound irradiation was 3.1% higher than that ofsimple mechanical irrigation. Under the condition of 4 hours and 48kPa ultrasound IIIpressure, DCPP yield was 92.3% and its purity was 99.7%. Finally, a 20kHz immersion ultrasound reactor was used for synthesizing DCPP.In this experiment, ultrasound irradiation played an important role, but magneticagitation was secondary. The energy of ultrasound is intensive because the probecontacts reactants directly and no need of media. In the initial stage, sound pressuredecides the reaction rate. Sound pressure increases, the yield of DCPP is higher. Butas time went on, yield of DCPP tended to a constant under different sound pressure.Under 70kPa and 2.5 hours, the yield of DCPP was 74.5% and the purity reached96.8%. This method would produce a by-product of methylphenylphosphinicchloride. The product was identified through GC-MS and IR. The spectrum of the productcoincided well with the standard spectrum of DCPP. The main functions of ultrasound to promote DCPP synthesis lie on its cavitation,oscillation, emulsification, and mass transfer is intensified. But ultrasound irradiationhad not changed mechanism of the reaction. This thesis provides a new technology tosynthesize DCPP and other Friedel-Crafts reaction. Another innovation in this thesis is that another cheap and safecomplexant—sodium chloride has been found, but pyridine, phosphorus oxychloride,and phosphoric anhydride etc mentioned in documents were given up. A feasible planon how to deal with waste residues was brought forward, thus its pollution toenvironment can be minimal.