Crystal Violet 염료 분자의 가수분해 및 자유 라디칼 반응성에 관한 분자 궤도론적 이해
Understanding the Molecular Orbital Theory on the Hydrolysis and Free Radical Reactivity of Crystal Violet Dye Molecule
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초록
과학수사 관점에서, 문서에 기록된 필기도구의 잉크중 Crystal Violet 염료분자(Hexamethylpararosaniline)의 탈색시간에 따르는 분해반응성을 파악하기 위하여, 분자궤도(MO: molecular orbital)론적인 방법으로 염료분자의 가수분해와 광산화 반응에 의한 자유 라디칼 반응성에 관하여 정량적으로 검토하였다. 염료분자의 계산된 MO함수는 εHOMO=−12.4640 ev., εSOMO= −3.21008 ev. 및εLUMO=4.4180 ev.이었다. 그러므로 각 MO함수 사이의 에너지 차이값(△E)으로 부터 염료분자는 가수분해 반응성(△E: εHOMO-εLUMO=7.77449 ev.) 보다는 자유 라디칼 반응성(△E: εHOMO-εSOMO= −4.54564 ev.)이 큰 분자임을 알았다. 이들 결과들에 기초하여, 가수분해반응은 C_7원자(methine carbon)에 대한 친핵성 첨가반응으로, 그리고 광산화 반응은 친핵성 라디칼에 의하여 일어난다. 따라서 두 반응들로부터 가수분해 반응 생성물은 9종, 그리고 광산화 반응 생성물은 7종으로 각각 예상되었다.
Abstract
In the context of a scientific criminal investigation, to better understand the degradation reactivity by decoloration time of the Crystal Violet dye (Hexamethylpararosaniline) molecule which is comprised of the ink ingredient that is used in writing tools, the hydrolysis and free radical reactivity by photooxidation of the dye molecule were discussed quantitatively using the MO (molecular orbital) theoretical method. The calculated MO functions of the dye molecule were εHOMO=12.4640 ev., εSOMO=3.21008 ev. and εLUMO=4.4180 ev., respectively. It was found that the dye molecule has a larger free radical reactivity(△E: εHOMO- εSOMO=4.54564 ev.) but a smaller value for hydrolysis (△E: εHOMO-εLUMO=7.77449 ev.) calculated as differences(△E) between each MO functions. Based on these findings, the two reactions will proceed that the one is hydrolysis by nucleophilic addition to the C_7 atom (methine carbon) and the other is photooxidation by a nucleophilic radical. Consequently, it was predicted that nine reaction products by hydrolysis and seven by photooxidation are obtained, respectively, from these two reactions.
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