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| 芳基乙酸与芳基丙酮经历C-C键断裂生成芳腈的研究
摘 要
腈基是重要的化学官能团，在化学合成方面运用非常广泛。腈类化合物不仅可以转化为醛、酸、胺、酰胺、羧酸衍生物、含氮杂环化合物等，也可以应用于生物医药、农药、材料、香料。腈类化合物合成的研究是现代科学研究的重要课题，许多化学工作者参与这项工作中。由醛到腈的转化、苄醇向腈的转化、芳基氯化物向腈的转化、酰胺向腈的转化，而酸向腈的转化、酮向腈的转化等是化学工作者们不断尝试的宝贵经验。
本文主要是从芳基乙酸向腈转化与芳基丙酮向腈转化的研究，芳基乙酸与芳基丙酮都是羰基位上的碳与羰基位相连的碳之间发生C-C键断裂，脱去羰基后与NaNO2提供的氮原子结合形成苯甲醛肟，再脱去一分子H2O最终生成腈。本文以无水FeCl3为催化剂，以NaNO2为氮源，来研究芳基乙酸和芳基丙酮经历C-C键断裂生成芳腈的反应，主要内容与结论如下：
（1）芳基乙酸经历C-C键断裂生成芳腈的研究，这里经过对催化剂、溶剂、温度、时间、氛围等因素的不断优化，得到最优反应条件为：0.5 mmol 4-溴苯乙酸、1 mmol无水FeCl3为催化剂、3 mmol NaNO2为氮源、DMSO为溶剂，50℃为反应温度，在1 atm空气氛围内反应10 h。该反应使用廉价安全的NaNO2作为氮源、避免使用有毒的且价格昂贵的催化剂或溶剂、降低了反应温度、操作更加简便。
考察了一系列带有取代基的芳基乙酸对于该反应的适应性，发现带有吸电子基团的芳基乙酸对该反应的适应性比带有供电子基团的芳基乙酸对该反应的适应性要强。在这些底物中，而联苯乙酸生成联苯甲腈的气相内标产率最高，说明对该反应对空间位阻较大的底物适应性更强。
（2）芳基丙酮经历C-C键断裂生成芳腈的研究，这里经过对催化剂、溶剂、温度、时间、氛围等因素的不断优化，得到最优反应条件为：0.5 mmol 4-甲氧基苯基丙酮、0.075 mmol无水FeCl3为催化剂、1.5 mmol NaNO2为氮源、超干DMSO为溶剂，90℃为反应温度，在氩气氛围下反应20 h。
考察了一系列取代基对该反应的适应性，发现该反应对带有吸电子基团的芳基丙酮的适应性高于对带有供电子基团的芳基丙酮的适应性。在对芳基丙酮的衍生物对该反应适应性的考察中，发现二苯乙酮与4-甲氧基苯乙酸两类化合物对该反应的适应性强，而对苯乙醛类化合物的适应性不太好，对2-四氢萘酮类化合物不反应。以甲基壬基甲酮为底物在最优条件下反应，底物大量剩余，该反应不能适用于脂肪烃。
关 键 词：腈类化合物；C-C键断裂；芳基乙酸；芳基丙酮；芳腈
ABSTRACT
The nitrile group is an important chemical functional group, which is widely used in chemical synthesis. Nitriles can not only be converted into aldehydes, acids, amines, amides,carboxylic acid derivatives, nitrogen-containing heterocyclic compounds, etc. but also can be used in biomedicine, pesticides, materials, and fragrances.The research on the synthesis of nitriles is an important subject ofmodern scientific research, and many chemists participate in this work. The reaction from aldehyde to nitrile,the reaction of benzyl alcohol to nitrile, the reaction of aryl chloride to nitrile, the conversion of amide to nitrile, the conversion of acid to nitrile, the conversion of ketone to nitrile, etc. are constantly tried by chemists.Valuable experience.
This article mainly focuses on the conversion of aryl aceticacid to nitrile and the conversion of aryl acetone to nitrile. Both aryl acetic acid and aryl acetone are cleavage of the C-C bond between the carbon at the carbonyl position and the carbon connected to the carbonyl position to remove the carbonyl group. Then it combines with the nitrogen atom provided by NaNO2 to form benzaldehyde oxime, and then removes a molecule of H2O to finally generate nitrile. In this paper, anhydrous FeCl3 is used as a catalyst and NaNO2 is used as a nitrogen source to study the reaction of aryl acetic acid and aryl acetone undergoing C-C bond cleavage to form aromatic nitrile. The main contents and conclusions are as follows:
and conclusions are as follows:
(1) The study of aryl acetic acid undergoing C-C bond cleavage to generate aromatic nitrile.After continuous optimization of catalyst, solvent, temperature, time,atmosphere and other factors, the optimal reaction conditions are: 0.5 mmol 4-bromophenylacetic acid, 1 mmol anhydrous FeCl3 is the catalyst,3 mmol NaNO2 is the nitrogen source, DMSO is the solvent, and the reaction temperature is 50℃. The reaction is carried out in 1 atm air atmosphere for 10 h.The reaction uses cheap and safe NaNO2 as the nitrogen source,avoids the use of toxic and expensive catalysts or solvents, reduces the reaction temperature, and makes the operation easier.
The adaptability of a series of aryl acetic acids with substituents to the reaction was investigated, and it was found that aryl acetic acid with electron withdrawing group was more adaptable tothe reaction than aryl acetic acid with electron donating group The adaptability should be strong. Among these substrates, the yield of the gas phase internal standard for felbinac to bibenzonitrile is the highest,indicating that the reaction is more adaptable to substrates with greater steric hindrance.
(2) The study of aryl acetone undergoing C-C bond cleavage to form aromatic nitrile.After continuous optimization of catalysts, solvents, temperature,time, atmosphere and other factors, the optimal reaction conditions are: 0.5 mmol 4-methoxyphenyl Acetone, 0.075 mmol anhydrous FeCl3 as catalyst, 1.5 mmol NaNO2 as nitrogen source, ultra-dry DMSO as solvent,90°C as the reaction temperature, reacted for 20 h under argon atmosphere.
The adaptability of a series of substituents to the reaction was investigated,and it was found that the adaptability of the reaction to arylacetone with electron-withdrawing group was higher than that of arylacetone with electron-donating group. In the investigation of the adaptability of p-arylacetone derivatives to thereaction, it was found that benzophenone and 4-methoxyphenylacetic acid havestrong adaptability to the reaction,while the adaptability to phenylacetaldehyde compounds It is not very good and does not react to 2-tetralone compounds. Using methyl nonyl ketone as the substrate for the reaction under optimal conditions,a large amount of substrate remains, and this reaction cannot be applied to aliphatic hydrocarbons.
KEY WORDS: Nitriles; C-C bond cleavage; aryl acetic acid; aryl acetone; aryl nitrile
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