Quantitative Analysis for a Color-Change of Humidity Indicator by Microscopic Absorption Spectrometry

Matsumoto, Tomoko; Mitsumura, Yoko; Miyamoto, Miyuki; Matsumoto, Jin; Shiragami, Tsutomu; Fueda, Yoshiyuki; Nobuhara, Kazunori; Yasuda, Masahide

doi:10.2116/analsci.27.623

Cited by 8 publications

(2 citation statements)

References 8 publications

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“…On the other hand, Gordeeva and co-workers have reported that acidic conditions were made by the reaction of SiO 2 with CaCl 2 under dry conditions [16]. In order to develop new type of humidity indicator, we mixed MgCl 2 -SiO 2 with pH-sensitive tetraphenylporphyrin and dried under heating to prepare a porphyrin-MgCl 2 -SiO 2 (Indicator F TM , Fuji Silysia), which caused color change from green under dry conditions to pink under wet conditions [17]. During the investigations, we measured the pH of the composites of Mg salts (MgCl 2 , MgSO 4 , Mg(NO 3 ) 2 ) with SiO 2 using several kinds of tetraarylporphyrins with different basicity [18].…”

Section: Introductionmentioning

confidence: 99%

Solid-Phase Aromatic Nitration with Mg(NO3)2 on Silica Gel

Matsumoto¹,

Yamauchi²,

Ishikawa³

et al. 2017

IJOC

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Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effort has been made on the improvement of nitration process without strong acids. We examined solid-phase aromatic nitration with Mg(NO 3 ) 2 on silica gel in order to establish the nitration process without strong acids. The nitration of 1,2-and 1,3-, 1,4-dimethoxybenzenes and 4-methylanisole with Mg(NO 3 ) 2 proceeded by heating on silica gel at 150˚C for 4 -5 h to produce the nitroaromatics. The nitration of 1,3,5-trimethoxybenzene produced the nitrated dimer, 2,4,6,2', 4',6'-hexamethoxy-3-nitrobiphenyl, which was not isolated in other solid-phase nitration. In the cases of naphthalene derivatives, the α-nitrated compounds were obtained. In the cases of p-cresol and 2-naphthol, the esterification occurred at the hydroxyl group to give 4-tolyl nitrate and 2-naphthyl nitrate, respectively. It is synthetic interest to note that nitrate esters were isolated in solid phase. Thus Mg(NO 3 ) 2 -SiO 2 composite was mild reagent for solid-phase nitration. Acidity of Mg(NO 3 ) 2 -SiO 2 composite was determined to be pH 0.96 by the measurement of absorption spectra on a micro spectrophotometer using meso-tetra(p-cyanophenyl)porphyrin as a pH-indicator. Mg(NO 3 ) 2 -SiO 2 composite made acidic conditions. Therefore, it was suggested that Mg(NO 3 ) 2 reacted with proton on silica gel to form the 2 NO + . Thus, electron-rich aromatic hydrocarbons led the efficient nitration through electrophilic attack of 2 NO + . After the nitration, acidic Mg(NO 3 ) 2 -SiO 2 composite could be turned into neutrality by exposing wet conditions and disposed safely since the composite did not involve harmful elements. Thus the solid-phase nitration using Mg(NO 3 ) 2 -SiO 2 composite will provide safety and environmentally conscious chemical process.

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Section: Introductionmentioning

confidence: 99%

Solid-Phase Aromatic Nitration with Mg(NO3)2 on Silica Gel

Matsumoto¹,

Yamauchi²,

Ishikawa³

et al. 2017

IJOC

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show abstract

“…It has been reported that MgCl 2 -SiO 2 releases protons under dry conditions, and goes back to neutral under wet conditions. At first, using five kinds of tetraarylporphyrins, the absorbance (A P ) at 515 nm due to a free base type and that (A G ) at 650 nm due to the protonated porphyrins were measured in a CHCl 3 -MeOH-water solution, whose apparent pH was adjusted by HClO 4 . Fraction (F-value) of A P [F A P /(A G A P )] was calculated at every apparent pH to produce apparent pH-profiles of the F-values for all porphyrins.…”

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Measurement of Acidity of Magnesium Salts-Silica Gel Composites by Microscopic Absorption Spectrometry Using Porphyrin as pH-indicator

et al. 2012

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Porphyrin-based sensor films for monitoring food spoilage

Altmann

Eden

Hüttmann

et al. 2023

Food Packaging and Shelf Life

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Quantitative Analysis for a Color-Change of Humidity Indicator by Microscopic Absorption Spectrometry

Cited by 8 publications

References 8 publications

Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel

Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel

Measurement of Acidity of Magnesium Salts-Silica Gel Composites by Microscopic Absorption Spectrometry Using Porphyrin as pH-indicator

Porphyrin-based sensor films for monitoring food spoilage

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Quantitative Analysis for a Color-Change of Humidity Indicator by Microscopic Absorption Spectrometry

Cited by 8 publications

References 8 publications

Solid-Phase Aromatic Nitration with Mg(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; on Silica Gel

Solid-Phase Aromatic Nitration with Mg(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; on Silica Gel

Measurement of Acidity of Magnesium Salts-Silica Gel Composites by Microscopic Absorption Spectrometry Using Porphyrin as pH-indicator

Porphyrin-based sensor films for monitoring food spoilage

Contact Info

Product

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Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel

Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel