The electrochemistry of β‐substituted tetraphenylporphyrins with a single ethyl acetoacetate (EAA), acetylacetone (acac) or ethyl acetate (EA) group and two antipodal H, Br or Ph groups was investigated in CH2Cl2 containing 0.1 M tetrabutylammonium perchlorate (TBAP) before and after addition of base to solution in the form of tetrabutylamonium hydroxide (TBAOH). The tri‐substituted porphyrins in their neutral form are represented as MTPP(EAA)X2 , MTPP(acac)X2 and MTPP(EA)X2 where TPP is the dianion of tetraphenylporphyrin, M = H2, NiII, CuII or ZnII and X = H, Br or Ph. The singly reduced porphyrins are relatively stable on the cyclic voltammetry timescale but this is not the case for the doubly reduced EAA and acac derivatives which are highly reactive at room temperature, leading to a porphyrin product assigned as containing a deprotonated EAA‐ or acac‐ (enolate) substituent. Enolate‐appended porphyrins were also in situ generated by the addition of TBAOH, resulting in mono‐anionic porphyrins which are harder to reduce by 110‐160 mV as compared to the neutral compounds having the same β‐substituents, suggesting a high degree of interaction between the deprotonated EAA‐ or acac‐substituent and the porphyrin π‐ring system. The chemically or electrochemically generated enolate‐appended porphyrin could also be irreversibly oxidized by one electron at peak potentials between 0.10 and 0.30 V, the exact value depending upon solvent and type of β‐diketo substituent.

中文翻译：

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在中性和碱性非水溶剂中用β-附加的乙酰乙酸乙酯（EAA）和乙酰丙酮（acac）对三取代卟啉进行电化学

在含0.1 M高氯酸四丁基铵（TBAP）的CH2Cl2中，研究了β-取代的四苯基卟啉与一个乙酰乙酸乙酯（EAA），乙酰丙酮（acac）或乙酸乙酯（EA）基团和两个对映H，Br或Ph基团的电化学反应，之前和之后将碱以氢氧化四丁铵（TBAOH）的形式加入溶液后。中性形式的三取代卟啉表示为MTPP（EAA）X2，MTPP（acac）X2和MTPP（EA）X2，其中TPP是四苯基卟啉的二价阴离子，M = H2，NiII，CuII或ZnII，X = H ，Br或Ph。在循环伏安法时标上，单还原的卟啉相对稳定，但是在室温下具有高反应活性的双还原的EAA和acac衍生物则不是这种情况。导致卟啉产物被指定为包含去质子化的EAA-或acac-（烯酸酯）取代基。通过添加TBAOH还可原位生成附有醇酸酯的卟啉，与具有相同β取代基的中性化合物相比，单阴离子卟啉的还原力降低了110-160 mV。在去质子化的EAA或acac取代基和卟啉π环系统之间。化学或电化学方法生成的带有烯醇盐的卟啉也可被一个电子在0.10至0.30 V之间的峰值电势不可逆地氧化，确切的值取决于溶剂和β-二酮取代基的类型。导致单阴离子卟啉与具有相同β取代基的中性化合物相比难以降低110-160 mV，这表明去质子化的EAA或ac取代基与卟啉π环之间存在高度的相互作用系统。化学或电化学方法生成的带有烯醇盐的卟啉也可被一个电子在0.10至0.30 V之间的峰值电势不可逆地氧化，确切的值取决于溶剂和β-二酮取代基的类型。导致单阴离子卟啉与具有相同β取代基的中性化合物相比难以降低110-160 mV，这表明去质子化的EAA或ac取代基与卟啉π环之间存在高度的相互作用系统。化学或电化学方法生成的带有烯醇盐的卟啉也可能被一个电子在0.10至0.30 V的峰值电势下不可逆地氧化，确切的值取决于溶剂和β-二酮取代基的类型。