Heindl A, Rau O, Spiteller G
Biomed Mass Spectrom. 1985 Feb;12(2):59-66. doi: 10.1002/bms.1200120203.
3,5-Dihydroxyphenylpropionic acid, 3,5-dihydroxycinnamic acid and 2,3-dihydroxycinnamic acid were detected for the first time to be components of human urine. In the course of this investigation all constitutional isomers of dihydroxy-benzoic, -phenylpropionic, -phenylacetic and -cinnamic acid were synthesized. Mass spectra and retention indices of methyl and trimethylsilyl (TMS) derivatives were determined. In contrast to many other substituted aromatic compounds the mass spectra of methyl and TMS derivatives of dihydroxy aromatic acids often allow a firm distinction to be made between constitutional isomers: TMS derivatives of aromatic acids containing two hydroxy groups located in the ortho position to each other can be recognized by ions resulting from a primary cleavage reaction mainly in the side chain or ester group, followed by loss of tetramethylsilane. In methyl derivatives of 1,2,3-trisubstituted isomers, methoxy groups are lost much more easily from the ions corresponding to the benzylic cleavage than in other isomers. Methyl derivatives of dihydroxycinnamic acids containing at least one methoxy group in the ortho position to the side chain are characterized by a fragmentation reaction, corresponding to the loss of dimethyl ether. TMS and methyl derivatives of 3,5-dihydroxy aromatic acids show unique structure-specific fragmentation reactions.
首次检测到3,5 - 二羟基苯丙酸、3,5 - 二羟基肉桂酸和2,3 - 二羟基肉桂酸是人类尿液的成分。在本研究过程中，合成了二羟基苯甲酸、二羟基苯丙酸、二羟基苯乙酸和二羟基肉桂酸的所有构造异构体。测定了甲基和三甲基硅烷基（TMS）衍生物的质谱和保留指数。与许多其他取代芳香族化合物不同，二羟基芳香酸的甲基和TMS衍生物的质谱通常能明确区分构造异构体：彼此处于邻位的含有两个羟基的芳香酸的TMS衍生物可通过主要在侧链或酯基中发生的初级裂解反应产生的离子识别，随后失去四甲基硅烷。在1,2,3 - 三取代异构体的甲基衍生物中，与苄基裂解相对应的离子中的甲氧基比其他异构体更容易失去。在侧链邻位含有至少一个甲氧基的二羟基肉桂酸的甲基衍生物的特征是发生对应于二甲醚损失的裂解反应。3,5 - 二羟基芳香酸的TMS和甲基衍生物显示出独特的结构特异性裂解反应。
