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EPR characterization of organic free radicals in marine diesel

机译：EPR表征船用柴油中的有机自由基

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The intensive unresolved central line associated with organic free radicals in electron paramagnetic resonance (EPR) spectra of petroleum is interpreted as resulting from the superposition of signals from different radical species with very close g values. The mobility of a free radical in crude oil is relatively low due to the high oil viscosity. Aimed at characterizing free radicals in the oil byproduct, the present study is concerned with the investigation of marine diesel (bunker), a low-viscosity oil. Marine diesel was studied by EPR spectroscopy at X-band (9 GHz) in the temperature range from 170 to 400 K. Despite the viscosity at room temperature (2.5·10−3 kg/m·s) and the tumbling correlation time for free radicals of about 10−7 s suggesting a high mobility of free radicals in marine diesel, the EPR spectra at room temperature did not exhibit resolved lines, but only an envelope with a poor signal-to-noise ratio. The same behavior was observed from 170 to 373 K. Above 373 K, the EPR spectrum exhibited resolved lines: a superposition of a septet-quartet, a sextet-quartet and a quintet-quartet group of lines was identified with the following parameters: g = 2.003 ± 0.001, proton hyperfine couplings A = 6.41 ± 0.03 G (septet) and A′ = 1.82 ± 0.02 G (quartet); g = 2.003 ± 0.001, A = 6.21 ± 0.03 G (sextet) and A′ = 1.64 ± 0.02 G (quartet); g = 2.003 ± 0.001, A = 6.16 ± 0.03 G (quintet) and A′ = 1.83 ± 0.02 G (quartet), which were attributed to phenalenyl radicals and their derivatives. Below 373 K, phenalenyl dimerization prevented its detection by EPR.
机译：石油的电子顺磁共振（EPR）光谱中与有机自由基相关的强烈的未解析中心线被解释为是来自不同自由基物种的信号的叠加，具有非常接近的g值。由于高油粘度，自由基在原油中的迁移率相对较低。为了表征石油副产物中的自由基，本研究与船用柴油（邦克）（一种低粘度的石油）的研究有关。在170至400 K的温度范围内，通过EPR光谱在X波段（9 GHz）上研究了船用柴油。尽管在室温下具有粘度（2.5·10 −3 kg / m·s）并且自由基的翻滚相关时间约为10 −7 s，表明自由基在船用柴油中具有很高的迁移率，室温下的EPR谱图未显示分解线，而仅显示了一个包络线。信噪比差。从170到373 K，观察到了相同的行为。在373 K以上，EPR谱图显示出分辨的谱线：用以下参数确定了七重奏组，六重奏组和五重奏组的重叠线。 = 2.003±0.001，质子超精细偶合A = 6.41±0.03 G（九重峰），A'= 1.82±0.02 G（四重峰）； g = 2.003±0.001，A = 6.21±0.03 G（六重奏），A'= 1.64±0.02 G（四重奏）; g = 2.003±0.001，A = 6.16±0.03 G（五重奏）和A'= 1.83±0.02 G（四重奏），这归因于菲基及其衍生物。低于373 K，苯二烯二聚化阻止了EPR的检测。

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