scholarly journals HISTOCHEMICAL AZO COUPLING REACTIONS OF THE PIGMENTS OF OBSTRUCTIVE ICTERUS AND OF HEMATOIDIN

1970 ◽  
Vol 18 (2) ◽  
pp. 75-79 ◽  
Author(s):  
R. D. LILLIE ◽  
P. PIZZOLATO
Keyword(s):  
Uric Acid ◽  
Coupling Reaction ◽  
Sodium Dithionite ◽  
Acid Extraction ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Alcohol Dehydration ◽  
Reactive Material ◽  
Tissue Protein ◽  
Exhaustive Extraction

Azo bilirubins and azohematoidins resist alcohol dehydration and mounting in resinous media after adequate coupling reactions. The azo colors are resistant to hydrochloric acid extraction (0.1 N 30 min routinely) but are bleached at varying rates according to the specific dye by sodium dithionite solution. Fresh dithionite is required. The azo coupling reaction of bile casts is prevented by ethanol acetic anhydride acetylation, restored by alcoholic KOH saponification and prevented completely by oxidation with 0.2% CrO3 (4 hr) or by a diammine silver, iodine, thiosulfate sequence. These oxidations do not alter the alkaline azo coupling reactions of tissue protein. Azo coupling of bile casts is unaltered by a 24-hr 10% iodine-methanol, 2-min thiosulfate sequence or by a 24-hr 0.1 M bisulfite reduction. The reactive bilirubin is resistant to hot methanol chloroform primary fixation as well as to exhaustive extraction by this solvent after formol fixation, although both of these procedures extract readily visible amounts of yellow material into the solvent. It appears that the azo-reactive material must be protein bound. Alkaline azo coupling with diazosafranin is weakened by lesser amounts and completely prevented by addition of equimolar or greater amounts of uric acid to the diazo.

scholarly journals THE QUESTION OF TRIAZENES IN THE TOTAL COLOR EFFECT OF THE PROTEIN AZO COUPLING REACTION IN HISTOCHEMISTRY

1970 ◽  
Vol 18 (3) ◽  
pp. 187-194 ◽  
Author(s):  
R. D. LILLIE
Keyword(s):  
Uric Acid ◽  
Coupling Reaction ◽  
Diazonium Salts ◽  
Acid Extraction ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Color Effect ◽  
Azure A ◽  
Safranin O ◽  
Methylene Violet

The suggestion that triazenes formed by union of alkalized diazonium salts with aliphatic amino groups contribute to the azo color reaction of tissue proteins is rejected. Deaminations of formaldehyde-fixed and other tissues were sufficient to render the previously oxyphil elements of these tissues basophilic to azure A-eosin B at the same pH level. After these deaminations there was no detectable difference in intensity or distribution of the azo coupling reaction. Freshly diazotized safranin O, dimethylphenosafranin (methylene violet) and the diazosulfanilic acid, azure A sequence technic were used as testing methods. Acid extraction even when prolonged to 24 hr and when acid concentration raised from 0.1 N to 0.24 N does not alter the intensity or distribution of the several azo coupling reactions as compared with unextracted preparations. Deliberate creation of triazenes by admixture of proline, diethylamine, hydroxylamine, hydrazine sulfate, glycine and uric acid, added to the diazo in stoichiometric excess, more or less completely inhibited azo coupling of all tissue elements. Uric acid and hydrazine were the most efiective, and then hydroxylamine, proline and diethylamine in that order. Reacidification of the uric acid compound to pH 2.2-2.5 for 10 min, filtration to remove liberated uric acid and realkalinization moderately restored the azo coupling capacity of diazosafranin. This illustrates acid destruction of a triazene of this diazotate. It is concluded that triazenes with tissue aliamino groups play no significant part in the final color effect of azo coupling with the diazonium salts used.

Reactions of 4-Amino-3-penten-2-one and Its NSubstituted Derivatives with Diazonium Ions

1995 ◽  
Vol 60 (8) ◽  
pp. 1367-1379 ◽  
Author(s):  
Vladimír Macháček ◽  
Alexandr Čegan ◽  
Aleš Halama ◽  
Olga Rožňavská ◽  
Vojeslav Štěrba
Keyword(s):  
Coupling Reaction ◽  
Butyl Alcohol ◽  
Azo Compounds ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Alcohol Water ◽  
Diazonium Ions ◽  
Coupling Rate ◽  
Reaction Orders ◽  
Intramolecular Hydrogen

Azo coupling reactions of benzenediazonium salts with substituted 4-amino-3-penten-2-ones take place at the C-3 atom. 1H and 13C NMR spectroscopy has been used to study the structure of both the starting enaminones and coupling products. In CDCl3, 3-(4-chlorophenylhydrazono)-2-(4-methylphenylimino)-4-pentanone exists in hydrazo form whereas 4-amino-3-(4-chlorophenylazo)-3-penten-2-one is present as a mixture of two azo compounds differing probably in the arrangement of the intramolecular hydrogen bond. The azo coupling reaction kinetics have been studied in acetate buffers and methanol-water or tert-butyl alcohol-water mixtures. The coupling rate has been found independent of pH and buffer concentration. The reaction orders with respect to the starting compounds have been determined and the reaction mechanism is suggested. Linear dependence has been found between log kobs and substituent constants according to the Hammett or Yukawa-Tsuno equations.

scholarly journals Surface-plasmon-induced azo coupling reaction between nitro compounds on dendritic silver monitored by surface-enhanced Raman spectroscopy

RSC Advances ◽  
2017 ◽  
Vol 7 (17) ◽  
pp. 10259-10265 ◽  
Author(s):  
Feng-Hsuan Cho ◽  
Shan-Chi Kuo ◽  
Ying-Huang Lai
Keyword(s):  
Raman Spectroscopy ◽  
Surface Plasmon ◽  
Coupling Reaction ◽  
Surface Enhanced Raman Spectroscopy ◽  
Nitro Compounds ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Azo coupling reactions with a 4-NTP-functionalized Ag-Ds/GCE composites.

scholarly journals The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

2016 ◽  
Vol 12 ◽  
pp. 1987-2004 ◽  
Author(s):  
Faith M Akwi ◽  
Paul Watts
Keyword(s):  
Continuous Flow ◽  
Coupling Reaction ◽  
Azo Compounds ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Reaction Conditions ◽  
Flow Rates ◽  
Flow Synthesis ◽  
Optimum Flow

In this paper, a micro-fluidic optimized process for the continuous flow synthesis of azo compounds is presented. The continuous flow synthesis of Sudan II azo dye was used as a model reaction for the study. At found optimal azo coupling reaction temperature and pH an investigation of the optimum flow rates of the reactants for the diazotization and azo coupling reactions in Little Things Factory-MS microreactors was performed. A conversion of 98% was achieved in approximately 2.4 minutes and a small library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic systems. The scaled up synthesis of these compounds in PTFE tubing (i.d. 1.5 mm) was also investigated, where good reaction conversions ranging between 66–91% were attained.

scholarly journals HISTOCHEMICAL AZO COUPLING REACTIONS A CATECHOLAMINE IN ENTEROCHROMAFFIN CELLS IN PLACE OF OR IN ADDITION TO 5-HYDROXYTRYPTAMINE

1973 ◽  
Vol 21 (5) ◽  
pp. 455-463 ◽  
Author(s):  
R. D. LILLIE ◽  
P. PIZZOLATO ◽  
L. L. VACCA ◽  
R. A. CATALANO ◽  
P. T. DONALDSON
Keyword(s):  
Guinea Pig ◽  
Coupling Reaction ◽  
Enterochromaffin Cells ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Gastric Glands ◽  
Fluorescence Studies ◽  
Light Yellow ◽  
Prior Oxidation

Appreciable azo coupling of enterochromaffin cells (EC) and of adrenal medulla (AM) is restricted to the alkaline range, fading out around pH 6, negative at 3-5. Low pH (3.0) azo coupling of rat and mouse mast cells (MC) with diazosafranin correlates with their known content of 5-hydroxytryptamine (5-HT) and with the pH 3-9 range of deep red azo coupling color reaction of p-nitrodiazobenzene with 5-hydroxytryptophan and 5-HT. The MC reaction is covalent azo bonding and not cationic dye salt bonding. The MC reaction is not influenced by prior oxidation by HIO4, FeCl3, K2Cr2O7 or I2/CH3OH exposures which prevent azo coupling of EC and of AM. The oxidation blockades of the azo coupling of EC and AM are reversed by Na2S2O5, N2S2O4 or Na2S2O3 reductions. These reductions after oxidation do not affect the MC diazosafranin reaction. In vitro the azo coupling of 5-HT is only slightly retarded but not weakened by HIO4 oxidation and then slightly enhanced by Na2S2O3, while noradrenaline gives red before oxidation, light yellow after, and after Na2S2O3, again deep red, the control α-naphthol giving deep red with p-nitrodiazobenzine at all three phases, before HIO4, between HIO4 and after Na2S2O3. Indole reactions for EC have been reported on glutaraldehyde (G), acetaldehyde and acrolein fixed but not formaldehyde (F) fixed guinea pig duodenum by Solcia and Sampietro (63), Geyer (27) (G), Barter and Pearse (5, 6) and Lillie and Greco-Henson (44). Repetition of the Lillie and Greco-Henson test of combining in the same preparation a blue indole reaction (postcoupled benzylidene) and a red azo coupling reaction with p-nitrodiazobenzene in both sequences disclosed numerous red EC and blue Paneth cells and eosinophil leukocytes, alike on F and G tissue. Direct observation during the second reaction and color photography of the same field after each of the two reactions showed that no red stained cell was replaced by a blue or purple one, and that no blue stained cell altered its color to purple or red. Moreover, azo positive cells were seen in the epithelium of the tips of the villi and in the sides of the gastric glands of the guinea pig pylorus and fundus. Indole positive cells did not occur in villus tip or pyloric gland epithelium and were restricted to fundus chief cells. It is concluded that the azo reactive substance in EC is a catechol and not 5-HT. The fluorescence studies have indicated the presence of 5-HT in EC, but the quantity present is insufficient for the acid azo coupling reaction shown by rat and mouse MC with diazosafranin.

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

An Unprecedented Cyano-Induced Sodium Nitrite-Catalyzed C(sp3)-H and C(sp2)-H Coupling Reaction

2018 ◽  
Vol 15 (7) ◽  
pp. 989-994 ◽  
Author(s):  
Ling Li ◽  
Bo Su ◽  
Yuxiu Liu ◽  
Qingmin Wang
Keyword(s):  
Sodium Nitrite ◽  
Oxidative Coupling ◽  
High Resolution Mass Spectrometry ◽  
Coupling Reaction ◽  
13C Nmr Spectroscopy ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
1H And 13C Nmr ◽  
Oxidative Coupling Reaction ◽  
Oxidative Coupling Reactions

Aim and Objective: During the investigation of sodium nitrite-catalyzed oxidative coupling reaction of aryls, an unprecedented C(sp2)-H and C(sp3)-H coupling of substituted 2-aryl acetonitrile was found. Materials and Methods: The structure of the coupled product was confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry (HRMS), and comparison of its derivatives with known compounds. The effects of methoxy group in the benzene ring on the reaction were evaluated. Results: The optimized reaction conditions are summarized as follows: CF3SO3H/substrate = 1.5 equiv., NaNO2/substrate = 0.3 equiv., CH3CN as solvent. 2-(4-Methoxyphenyl)acetonitrile and 2-(3,4,5- trimethoxyphenyl)acetonitrile could also generate C(sp2)-H and C(sp3)-H coupling. The coupling reaction occurred as a typical radial mechanism. Conclusion: An unprecedented cyano-induced, NaNO2-catalyzed oxidative C(sp3)-H and C(sp2)-H coupling was reported. The reaction proceeded under very mild conditions, using O2 in the air as terminal oxidant. The unique oxidative manner might provide more inspiration for the development of intriguing oxidative coupling reactions.

scholarly journals 5-((8-Hydroxyquinolin-5-yl)diazenyl)-3-methyl-1H-pyrazole-4-carboxylic Acid

Molbank ◽  
10.3390/m1238 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1238
Author(s):  
Ion Burcă ◽  
Valentin Badea ◽  
Calin Deleanu ◽  
Vasile-Nicolae Bercean
Keyword(s):  
Chemical Structure ◽  
Functional Group ◽  
Coupling Reaction ◽  
2D Nmr ◽  
Azo Coupling ◽  
2D Nmr Spectroscopy ◽  
Azo Compound ◽  
Ft Ir ◽  
New Compounds ◽  
Carboxylic Functional Group

A new azo compound was prepared via the azo coupling reaction between 4-(ethoxycarbonyl)-3-methyl-1H-pyrazole-5-diazonium chloride and 8-hydroxyquinoline (oxine). The ester functional group of the obtained compound was hydrolyzed and thus a new chemical structure with a carboxylic functional group resulted. The structures of the new compounds were fully characterized by: UV–Vis, FT-IR, 1D and 2D NMR spectroscopy, and HRMS spectrometry.

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Synthesis ◽  
2020 ◽  
Vol 52 (17) ◽  
pp. 2483-2496
Author(s):  
Johannes F. Teichert ◽  
Lea T. Brechmann
Keyword(s):  
Coupling Reaction ◽  
Reactive Intermediates ◽  
Transfer Hydrogenation ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Starting Point ◽  
Bond Forming Reactions ◽  
Hydrogenation Reactions ◽  
Multicomponent Coupling Reactions ◽  
Trapping Reactions

The key reactive intermediate of copper(I)-catalyzed alkyne semihydrogenations is a vinylcopper(I) complex. This intermediate can be exploited as a starting point for a variety of trapping reactions. In this manner, an alkyne semihydrogenation can be turned into a dihydrogen­-mediated coupling reaction. Therefore, the development of copper-catalyzed (transfer) hydrogenation reactions is closely intertwined with the corresponding reductive trapping reactions. This short review highlights and conceptualizes the results in this area so far, with H2-mediated carbon–carbon and carbon–heteroatom bond-forming reactions emerging under both a transfer hydrogenation setting as well as with the direct use of H2. In all cases, highly selective catalysts are required that give rise to atom-economic multicomponent coupling reactions with rapidly rising molecular complexity. The coupling reactions are put into perspective by presenting the corresponding (transfer) hydrogenation processes first.1 Introduction: H2-Mediated C–C Bond-Forming Reactions2 Accessing Copper(I) Hydride Complexes as Key Reagents for Coupling Reactions; Requirements for Successful Trapping Reactions 3 Homogeneous Copper-Catalyzed Transfer Hydrogenations4 Trapping of Reactive Intermediates of Alkyne Transfer Semi­hydrogenation Reactions: First Steps Towards Hydrogenative Alkyne Functionalizations 5 Copper(I)-Catalyzed Alkyne Semihydrogenations6 Copper(I)-Catalyzed H2-Mediated Alkyne Functionalizations; Trapping of Reactive Intermediates from Catalytic Hydrogenations6.1 A Detour: Copper(I)-Catalyzed Allylic Reductions, Catalytic Generation of Hydride Nucleophiles from H2 6.2 Trapping with Allylic Electrophiles: A Copper(I)-Catalyzed Hydro­allylation Reaction of Alkynes 6.3 Trapping with Aryl Iodides7 Conclusion

Selectfluor-induced C(sp2)–O coupling reaction of N-substituted anilines with hydroxylamine derivatives

2018 ◽  
Vol 16 (33) ◽  
pp. 6017-6024 ◽  
Author(s):  
Bin Sun ◽  
Shi Yin ◽  
Xiaohui Zhuang ◽  
Can Jin ◽  
Weike Su
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Substituted Anilines ◽  
Metal Free ◽  
Cross Coupling Reactions ◽  
Hydroxylamine Derivatives

We developed a novel metal-free method for the construction of C(sp2)–O bonds via oxidative cross-coupling reactions between various N-substituted anilines and hydroxylamine derivatives just using commercially available Selectfluor as an oxidant.

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