TA与NMP形成的加合物晶体表征

Characterization of adductive crystal of terephthalic acid and N-methyl pyrrolidone

采用高效液相色谱(HPLC)、热重(TG)、X线衍射(XRD)、分光光度法等方法对溶剂N-甲基吡咯烷酮(NMP)与对苯二甲酸(TA)形成的加合物晶体进行表征,所形成的加合物是1个TA分子与2个NMP分子通过O—H…O的氢键作用形成的结晶体,该晶体在50℃以上不稳定,易受热分解而脱除溶剂.通过计算得出,TA与NMP之间的氢键键能为-87.8KJ/mol,属于较强类型的氢键作用.研究表明,加合结晶可以除去TA固体残渣中97%以上的有色杂质,是一种新型的结晶分离方法.

Adductive crystals formed by terephthalic acid （TA） and N methyl pyrrolidone （NMP） were measured and characterized by using high performance liquid chromatography （HPLC）, thermo gravimetric （TG）, X-ray diffraction （XRD） and spectrophotometry. The adduct was a crystal consisting of one TA molecule and two NMP molecules tied by O-H…O hydrogen-bond. The crystal was unstable above 50 ℃ at which it is prone to decomposition to disengage the solvent. The computational hydrogen- bonding energy between TA and NMP is -87. 8 KJ · mol^-1, which can be categorized to the relatively strong hydrogen bond. Results show that the adductive crystallization is an effective separation method of recovering the terephthalic acid residue, by which 97% colored impurities in TA residue can be removed.