THE INTERACTION OF o-DIPHENOLS WITH α-DIKETONES: THE REACTION OF 5,6-DIHYDROXY-N-METHYLINDOLE WITH DEHYDROASCORBIC ACID

1964 ◽  
Vol 42 (6) ◽  
pp. 1401-1408 ◽  
Author(s):  
G. L. Mattok ◽  
R. A. Heacock
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Room Temperature ◽  
Indole Derivative ◽  
Dehydroascorbic Acid

5,6-Dihydroxy-N-methylmdole readily reacts with dehydroascorbic acid in aqueous solution at room temperature. The o-diphenol system of the indole derivative interacts with the α-diketone function of dehydroascorbic acid to form a 1,4-benzodioxane derivative. This type of reaction appears to be a general one since similar interactions occur between other o-diphenols and α-diketones. The mechanism by which the 1,4-benzodioxane derivative is obtained when adrenochrome is reduced with ascorbic acid is discussed.

Stability of Ascorbic Acid in Reconstituted Frozen Orange Juice

1977 ◽  
Vol 40 (9) ◽  
pp. 584-585 ◽  
Author(s):  
PRISCILLA B. HORTON ◽  
SHERMAN R. DICKMAN
Keyword(s):  
Ascorbic Acid ◽  
Orange Juice ◽  
Phosphate Buffer ◽  
High Speed ◽  
Room Temperature ◽  
Phosphate Buffer Solution ◽  
Dehydroascorbic Acid ◽  
Temperature Stability ◽  
Buffer Solution

The sum of ascorbic acid and dehydroascorbic acid (physiologically available ascorbic acid), in reconstituted orange juice was remarkably stable over a 2-week period, both at 4 C and at room temperature. Stability was not affected by the aerating effect of blendorizing at high speed for 2 min. Stability was only partially due to the pH of orange juice, since available ascorbic acid declined more rapidly in a phosphate buffer solution at the same pH.

ON THE SPECIFICITY OF DYE TITRATION FOR ASCORBIC ACID

1946 ◽  
Vol 24b (1) ◽  
pp. 37-45 ◽  
Author(s):  
Jules Tuba ◽  
George Hunter ◽  
Helen Ruth Steele
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Room Temperature ◽  
Dehydroascorbic Acid ◽  
Usual Method ◽  
Plant Materials ◽  
Treated Plant

The 2,6-dichlorophenolindophenol method of assay of vitamin C has been critically examined with respect to a number of fresh, boiled, and otherwise treated plant materials. Comparative values are given for ascorbic acid as determined by the usual method, for non-vitamin C reductants, and for dehydroascorbic acid.In the fresh uncooked materials examined, non-vitamin C reductants were not found and only in cabbage, peas, and pigweed leaves did dehydroascorbic exceed 10% of the ascorbic acid value.Boiling produced significant amounts of non-vitamin C reductant in cabbage and peas.In rose hips the dye titration gives an accurate measure of ascorbic acid. The amounts of dehydroascorbic acid and non-vitamin C reductant, even under storage at room temperature for over a year, are insignificant.It is concluded that the 2,6-dichlorophenolindophenol method of assay of vitamin C is highly specific but in the case of certain cooked foodstuffs non-vitamin C dye reductants may, without check by other methods, introduce significant errors.

Ređuktone und Reduktonate, I Das Redoxpaar Dehydroascorbinsäure-Ascorbinsäure und ihre Anionen / Reductones and Reductonates, I The Redox Pair Dehydroascorbic Acid-Ascorbic Acid and Anions

1977 ◽  
Vol 32 (5) ◽  
pp. 562-568 ◽  
Author(s):  
Rudolf Matusch
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Nmr Spectroscopy ◽  
Oxidation Rate ◽  
Lactone Ring ◽  
Dehydroascorbic Acid ◽  
Hydroxyl Group ◽  
Redox Pair ◽  
Measurable Amount ◽  
Dehydro Ascorbic Acid

On the basis of NMR spectroscopy (1H and 13C) it can be shown that in water, dimethylsulfoxide and p-dioxane only the tautomer 1 of L-ascorbic acid is found in a measurable amount. Upon formation of the mono-anion la deprotonation occurs on the hydroxyl group attached to C-3; in addition the hydroxyl group on C-2 is deprotonated in case of the di-anion 1b. Both anions do not open the lactone ring.After oxidation with iodine in aqueous solution only the dimer of dehydroascorbic acid is detected. This is hydrolized with a half-life of three hours to the monomeric dehydro ascorbic acid dihydrate 7. In dimethylsulfoxide the oxidation rate is decreased, and therefore the formation of the monomeric non-hydratized dehydroascorbic acid 10 can be monitored. This undergoes ringclosure relatively fast to give the half-ketal 13, the reaction of which via 14 leads to the optical active dimeric dehydroascorbic acid 6. The L-ascorbic acid acetonide 15 is oxidised by iodine to 16 which undergoes racemization via the enol 17 to give 18. This forms an equilibrium with compound 19.

Effects of Copper Ions and Chelate Agent on Output of Ascorbic Acid Fuel Cell

2011 ◽  
Author(s):  
Ryota Furugori ◽  
Seiki Ikeda ◽  
Makoto Tanaka
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Fuel Cell ◽  
Oxidation Reaction ◽  
Room Temperature ◽  
Copper Ions ◽  
Chelating Agent ◽  
Chelate Agent ◽  
Acid Aqueous Solution ◽  
Type Fuel

A catalyst plays an important role in fuel cell because of promotion of chemical reaction for room temperature type fuel cell. In general, platinum is adopted as a catalyst even though it is very expensive. An ascorbic acid aqueous solution is able to react without catalyst for the oxidation reaction. At first, authors made sure of generation of the electric output using ascorbic acid for fuel without the catalyst. Next, we were able to increase the electric output with adding to metal ions to ascorbic acid aqueous solution. Finally, high and stable electric output was obtained by using the chelating agent.

scholarly journals Practical Synthesis of 2-Iodosobenzoic Acid (IBA) without Contamination by Hazardous 2-Iodoxybenzoic Acid (IBX) under Mild Conditions

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1897
Author(s):  
Hideyasu China ◽  
Nami Kageyama ◽  
Hotaka Yatabe ◽  
Naoko Takenaga ◽  
Toshifumi Dohi
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Practical Method ◽  
Hypervalent Iodine ◽  
Mild Conditions ◽  
Sequential Procedures ◽  
Iodine Compounds ◽  
Practical Synthesis ◽  
Iodosobenzoic Acid ◽  
Lower Temperature

We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone® in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound.

scholarly journals Self-assembly induced luminescence of Eu3+-complexes and application in bioimaging

2021 ◽  
Author(s):  
Ping-Ru Su ◽  
Tao Wang ◽  
Pan-Pan Zhou ◽  
Xiao-Xi Yang ◽  
Xiao-Xia Feng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Luminescence Intensity ◽  
Self Assembly ◽  
Room Temperature ◽  
Molecular Motion ◽  
Proof Of Concept ◽  
Room Temperature Phosphorescence ◽  
New Strategy ◽  
Size Controlled

Abstract Design and engineering of highly efficient emitting materials with assembly-induced luminescence, such as room temperature phosphorescence (RTP) and aggregation-induced emission (AIE), have stimulated extensive efforts. Here, we propose a new strategy to obtain size-controlled Eu3+-complex nanoparticles (Eu-NPs) with self-assembly induced luminescence (SAIL) characteristics without encapsulation or hybridization. Compared with previous RTP or AIE materials, the SAIL phenomena of increased luminescence intensity and lifetime in aqueous solution for the proposed Eu-NPs are due to the combined effect of self-assembly in confining the molecular motion and shielding the water quenching. As a proof of concept, we also show that this system can be further applied in bioimaging, temperature measurement and HClO sensing. The SAIL activity of the rare-earth (RE) system proposed here offers a further step forward on the roadmap for the development of RE light conversion systems and their integration in bioimaging and therapy applications.

Notizen:Phosphorescence Decay in Thallium-Doped Ammonium Chloride

1978 ◽  
Vol 33 (10) ◽  
pp. 1241-1242 ◽  
Author(s):  
S. Chaudhari ◽  
T. R. Joshi ◽  
R. V. Joshi
Keyword(s):  
Aqueous Solution ◽  
Ammonium Chloride ◽  
Mechanical Treatment ◽  
Room Temperature ◽  
Host Lattice ◽  
Luminescence Decay ◽  
Decay Rates ◽  
Negative Ion ◽  
Ultraviolet Emission ◽  
Near Ultraviolet

Abstract The phosphorescence decay rates of thallium-doped ammonium chloride (NH4Cl:Tl) phosphors, prepared by crystallization from aqueous solution, have been studied at room temperature for near-ultraviolet emission. The effects of impurity concentration as well as thermal and/or mechanical treatment on the decay rates have been examined. Phosphorescence centres consisting of a Tl+ion and a nearby negative ion vacancy are suggested to be responsible for the observed luminescence decay. The changes in the decay characteristics after pretreatments are explained on the basis of the location of the centres in normal and distorted regions of the host lattice.

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