The rapid expansion of the dye industry has led to severe environmental pollution. The lack of real-time direct determination methods for dye intermediates is a key factor in high pollution emissions and low product quality in the continuous synthesis of dyes. This study proposes an accessible, fast, and precise approach for the clean and direct determination of 3-(N,N-Diethylamino)acetanilide (DEAA), a dye intermediate used in the synthesis of the azo dye Disperse Violet 93:1. For precise DEAA quantification, we developed a multi-pathlength and multi-wavelength coupled differential photometric approach based on the absorption spectra characteristics of DEAA at various concentrations and optical pathlengths. A relatively stable analytical sensitivity (0.5671–66.2630) and a large concentration range of 0.01–11% were obtained. Compared to the traditional single-optical pathlength and single-wavelength quantification, this new method possessed 119 times higher sensitivity. The maximum quantitative relative error decreased from 9.17% to 2.44%. The orbital contribution and distinctive peak electronic excitation mechanism of DEAA were uncovered using TD-DFT. By comparing the oscillator strength and peak position variations between the target DEAA and coexisting sulfuric acid, the unique spectral behavior of DEAA, such as its high sensitivity and selectivity, was explained. In addition to providing a reference for real-time industrial dye and intermediate monitoring, this study lays the methodological groundwork for future research. In light of the new method's short time consumption and non-secondary pollution benefits, we further believe it will be crucial in controlling the industrial synthesis process in order to improve product quality, resource conversion efficiency, and effectively prevent excessive pollution generation.

中文翻译：

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染料工业污染控制的有效措施：直接测定3-(N,N-二乙氨基)乙酰苯胺的实验和DFT研究


染料工业的快速扩张导致了严重的环境污染。染料中间体缺乏实时直接测定方法是染料连续合成过程中污染排放高、产品质量低的关键因素。本研究提出了一种简便、快速且精确的方法来清洁和直接测定 3-(N,N-二乙基氨基)乙酰苯胺 (DEAA)，这是一种用于合成偶氮染料分散紫 93:1 的染料中间体。为了实现 DEAA 的精确定量，我们根据 DEAA 在不同浓度和光程下的吸收光谱特征，开发了一种多光程、多波长耦合的差分光度测量方法。获得了相对稳定的分析灵敏度（0.5671–66.2630）和0.01–11%的大浓度范围。与传统的单光程和单波长定量相比，这种新方法的灵敏度提高了119倍。最大定量相对误差从9.17%下降到2.44%。使用 TD-DFT 揭示了 DEAA 的轨道贡献和独特的峰值电子激发机制。通过比较目标 DEAA 和共存硫酸之间的振荡器强度和峰位置变化，解释了 DEAA 独特的光谱行为，例如其高灵敏度和选择性。该研究除了为实时工业染料和中间体监测提供参考外，还为未来的研究奠定了方法学基础。 鉴于新方法耗时短、无二次污染的优点，我们进一步认为，控制工业合成过程对于提高产品质量、资源转化效率、有效防止过度污染产生至关重要。