The colour reaction of phenols with the Gibbs reagent

Svobodová, D.; Křenek, Petr; Fraenkl, Max; Gasparič, J.

doi:10.1007/bf01201610

Cited by 9 publications

(6 citation statements)

References 13 publications

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“…Solvolysis of Gibbs reagent (1) yields dichlorobenzoqulnone monoimine (2), which attacks the para position of the phenol (3). The adduct (4) deprotonates and the resulting intermediate (5) loses H+ and R" to form 2,6-dichloroindophenol (6). (In the case of R = H, Intermediate ( 5) is oxidized to (6) by reaction with a second molecule of (2).…”

Section: Resultsmentioning

confidence: 99%

“…The adduct (4) deprotonates and the resulting intermediate (5) loses H+ and R" to form 2,6-dichloroindophenol (6). (In the case of R = H, Intermediate ( 5) is oxidized to (6) by reaction with a second molecule of (2). )…”

Section: Resultsmentioning

confidence: 99%

“…loses H+ and Rto form 2,6-dichlorolndophenol(6). ( I n the case of R = H, intermediate (5) is oxidized to (6) by reaction with a second molecule of (2).…”

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confidence: 99%

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Reaction of Gibbs reagent with para-substituted phenols

Josephy¹,

Damme²

1984

Anal. Chem.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Reaction of Gibbs reagent with para-substituted phenols

Josephy¹,

Damme²

1984

Anal. Chem.

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“…Full conversion of phenol was reported using a 10-fold excess at pH 10 after approximately 10−20 min at μM concentrations. 517 204 was used by Ang et al for the directed evolution of an aniline dioxygenase for bioremediation purposes, targeting the resulting catechol derivatives. 518 Arnold's group used it in HTS of dioxygenase activity using solid-phase digital imaging 486 and for the evolution of a toluene dioxygenase toward 4-picoline (4-methylpyridine).…”

Section: Electrophilic Aromatic Substitution (S Ear ) With Activated ...mentioning

confidence: 99%

“…As with 203 , only hydrogen, halide, or alkoxy substituents are tolerated. , Even though decomposition of the quinoneimine was shown to occur in alkaline medium, the formation of the product is favored, and the reaction is not hampered by prolonged reaction times. Full conversion of phenol was reported using a 10-fold excess at pH 10 after approximately 10–20 min at μM concentrations …”

Section: Chromo- and Fluorogenic Probes For Phenolsmentioning

confidence: 99%

Enlightening the Path to Protein Engineering: Chemoselective Turn-On Probes for High-Throughput Screening of Enzymatic Activity

et al. 2023

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Many successful stories in enzyme engineering are based on the creation of randomized diversity in large mutant libraries, containing millions to billions of enzyme variants. Methods that enabled their evaluation with high throughput are dominated by spectroscopic techniques due to their high speed and sensitivity. A large proportion of studies relies on fluorogenic substrates that mimic the chemical properties of the target or coupled enzymatic assays with an optical read-out that assesses the desired catalytic efficiency indirectly. The most reliable hits, however, are achieved by screening for conversions of the starting material to the desired product. For this purpose, functional group assays offer a general approach to achieve a fast, optical read-out. They use the chemoselectivity, differences in electronic and steric properties of various functional groups, to reduce the number of false-positive results and the analytical noise stemming from enzymatic background activities. This review summarizes the developments and use of functional group probes for chemoselective derivatizations, with a clear focus on screening for enzymatic activity in protein engineering.

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Chemical characterization of commercial liquid smoke products

Montazeri

Oliveira

Himelbloom

et al. 2012

Food Science & Nutrition

121

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The objective of this study was to determine important chemical characteristics of a full-strength liquid smoke, Code 10-Poly, and three refined liquid smoke products (AM-3, AM-10 and 1291) commercially available (Kerry Ingredients and Flavors, Monterey, TN). The pH of the products were significantly different (P < 0.05) and ranged from 2.3 (Code 10-Poly) to 5.7 (1291). The pH was inversely correlated with titratable acidity (R2 = 0.87), which was significantly different (P < 0.05) among products ranging from 10.3% acetic acid (Code 10-Poly) to 0.7% acetic acid (1291). Total phenol content was quantified using the Gibbs reaction; the only liquid smoke containing appreciable level of phenolic compounds was Code 10-Poly at 3.22 mg mL−1. Gas chromatography-mass spectrometry (GC-MS) analysis of liquid smoke dichloromethane extracts revealed that carbonyl-containing compounds were major constituents of all products, in which 1-hydroxy-2-butanone, 2(5H)-furanone, propanal and cyclopentenone predominated. Organic acids were detected by GC-MS in all extracts and correlated positively (R2 = 0.98) with titratable acidity. The GC-MS data showed that phenolic compounds constituted a major portion of Code 10-Poly, and were detected only in trace quantities in 1291. The refined liquid smokes had lighter color, lower acidity, and reduced level of carbonyl-containing compounds and organic acids. Our study revealed major differences in pH, titratable acidity, total phenol content, color and chemical make-up of the full-strength and refined liquid smokes. The three refined liquid smoke products studied have less flavor and color active compounds, when compared with the full-strength product. Furthermore, the three refined products studied have unique chemical characteristics and will impart specific sensorial properties to food systems. Understanding the chemical composition of liquid smokes, be these refined or full-strength products, is an important step to establish their functions and appropriate use in food systems.

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The colour reaction of phenols with the Gibbs reagent

Cited by 9 publications

References 13 publications

Reaction of Gibbs reagent with para-substituted phenols

Reaction of Gibbs reagent with para-substituted phenols

Enlightening the Path to Protein Engineering: Chemoselective Turn-On Probes for High-Throughput Screening of Enzymatic Activity

Chemical characterization of commercial liquid smoke products

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