Tajima S, Fujizuka A, Nakajima S, Takahashi Y, Sckiguchi O
Chemistry and Materials Science, Gunma National College of Technology, 580 Toriba, Maebashi, Gunma, Japan.
Rapid Commun Mass Spectrom. 2000;14(14):1195-9. doi: 10.1002/1097-0231(20000730)14:14<1195::AID-RCM8>3.0.CO;2-L.
Unimolecular metastable decomposition of diethoxymethane (CH(2)(OCH(2)CH(3))(2), 1) upon electron impact has been investigated by means of mass-analyzed ion kinetic energy (MIKE) spectrometry and theD-labeling technique in conjunction with thermochemistry. The m/z 103 ion (M - H : CH(OCH(2)CH(3)) = O(+)CH(2)CH(3)) decomposes into the m/z 47 ion (protonated formic acid, CH(OH) = O(+)H) by consecutive losses of two C(2)H(4) molecules via an m/z 75 ion. The resulting product ion at m/z 47 further decomposes into the m/z 29 and 19 ions by losses of H(2)O and CO, respectively, via an 1,3-hydroxyl hydrogen transfer, accompanied by small kinetic energy release (KER) values of 1.3 and 18.8 meV, respectively. When these two elimination reactions are suppressed by a large isotope effect, however, another 1,1-H(2)O elimination with a large KER value (518 meV) is revealed. The m/z 89 ion (M - CH(3) : CH(2)(OCH(2)CH(3))O(+) = CH(2)) decomposes into the m/z 59 ion (CH(3)CH(2)O(+) = CH(2)) by losing CH(2)O in the metastable time window. The source-generated m/z 59 ion (M - OCH(2)CH(3) : CH(2) = O(+)CH(2)CH(3)) decomposes into the m/z 41 (CH(2) = CH(+)CH(2)) and m/z 31 (CH(2) = O(+)H) ions by losses of H(2)O and C(2)H(4), respectively, with considerable hydrogen scrambling prior to decomposition. Copyright 2000 John Wiley & Sons, Ltd.
利用质量分析离子动能（MIKE）光谱法、D标记技术并结合热化学方法，研究了二乙氧基甲烷（CH(2)(OCH(2)CH(3))(2)，1）在电子轰击下的单分子亚稳分解。质荷比为103的离子（M - H：CH(OCH(2)CH(3)) = O(+)CH(2)CH(3)）通过连续失去两个C(2)H(4)分子，经质荷比为75的离子分解为质荷比为47的离子（质子化甲酸，CH(OH) = O(+)H）。所得质荷比为47的产物离子分别通过失去H(2)O和CO，经1,3 - 羟基氢转移进一步分解为质荷比为29和19的离子，伴随的小动能释放（KER）值分别为1.3和18.8 meV。然而，当这两个消除反应被大的同位素效应抑制时，会揭示出另一个具有大KER值（518 meV）的1,1 - H(2)O消除反应。质荷比为89的离子（M - CH(3)：CH(2)(OCH(2)CH(3))O(+) = CH(2)）在亚稳时间窗口内通过失去CH(2)O分解为质荷比为59的离子（CH(3)CH(2)O(+) = CH(2)）。源产生的质荷比为59的离子（M - OCH(2)CH(3)：CH(2) = O(+)CH(2)CH(3)）分别通过失去H(2)O和C(2)H(4)分解为质荷比为41（CH(2) = CH(+)CH(2)）和质荷比为31（CH(2) = O(+)H）的离子，在分解之前有相当程度的氢重排。版权所有2000约翰威立父子有限公司。
