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 INTERACTION OF HYDRIDE Σ-COMPLEX OF 5,7-DINITRO-8-HYDROXYQUINOLINE WITH SALTS OF AROMATIC DIAZO COMPOUNDS

2019 ◽  
Vol 62 (11) ◽  
pp. 85-91 ◽  
Author(s):  
Il'ya I. Ustinov ◽  
Nikolay V. Khlytin ◽  
Igor' V. Blokhin ◽  
Irina V. Shakhkel'dyan ◽  
Yuriy M. Atroshchenko ◽  
...  
Keyword(s):  
Diazo Compound ◽  
Coupling Reaction ◽  
Diazo Compounds ◽  
Azo Compounds ◽  
Azo Coupling ◽  
Absorption Bands ◽  
Stretching Vibrations ◽  
Intramolecular Hydrogen ◽  
Yield And Purity ◽  
Mild Acid

Interaction between 5,7-dinitro-8-hydroxyquinoline hydride anionic σ-adduct and chlorides of substituted aryldiazonium in water yielded 5-arylazo-7-nitro-8-hydroxyquinolines, the substitution products of the nitro group at the C-5 σ-adduct position. The direction of the reaction agrees with the quantum-chemical calculations carried out earlier and the GMLA principle, which assumes that the mild acid, which is a diazocathione, will attack the reaction center to which the softest base corresponds, that is, the least negatively charged C-5 carbon atom, in contrast to the C-7 atom. It is shown that the yield of the product increases with the presence of an electron-withdrawing substituent in the diazocomponent. Also in this study, the synthesis of the hydride σ-adduct of 5,7-dinitro-8-hydroxyquinoline was optimized. It was found that the use of pure dimethylacetamide as a solvent, as well as the addition of sodium carbonate, increases the yield and purity of the synthesized σ-adduct. The structure of the obtained compounds was proved by the methods of NMR and IR spectroscopy. In the IR spectra of all synthesized azo compounds, weak absorption bands corresponding to the stretching vibrations of the azogroup (N = N) are fixed in the range of 1400-1465 cm-1, which also indirectly confirms the expected direction of the reaction. Otherwise, the bands of the azogroup vibrations would be shifted to the 1500-1600 cm-1 region as a result of azo-hydrazoic tautomerism. In 1H NMR spectra of synthesized compounds, there is no proton signal of intramolecular hydrogen bond at δ 14-15 ppm, characteristic of the hydrazine form. The proton signals of the arylazo group also confirm the presence of the latter. The use of anionic hydride σ-complexes of dinitroquinoline derivatives as azo-component in the reaction with aromatic diazo compound expands the synthetic possibilities of the azo coupling reaction and allows to obtaine new nitroazoquinolines.

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 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 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 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.

Ring Closure of Azo Compounds to 1,2-Annulated Benzimidazole Derivatives and Further Evidence of Reversibility of the Azo-Coupling Reaction

2015 ◽  
Vol 80 (4) ◽  
pp. 2216-2222 ◽  
Author(s):  
Erminia Del Vecchio ◽  
Carla Boga ◽  
Luciano Forlani ◽  
Silvia Tozzi ◽  
Gabriele Micheletti ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Ring Closure ◽  
Azo Compounds ◽  
Benzimidazole Derivatives ◽  
Azo Coupling

Mechanism of azo coupling reactions. Part 34. Reactivity of five-membered ring heteroaromatic diazonium ions

1986 ◽  
Vol 64 (6) ◽  
pp. 1102-1107 ◽  
Author(s):  
Heinz Diener ◽  
Heinrich Zollinger
Keyword(s):  
Rate Constants ◽  
Chemical Shifts ◽  
Reaction System ◽  
Membered Ring ◽  
Disulfonic Acid ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
H Nmr ◽  
Ph Values ◽  
Diazonium Ions

The azo coupling reactions of six five-membered ring heteroaromatic diazonium ions with 2-naphthol-3,6-disulfonic acid are investigated kinetically at various pH values. The dependence of the measured rate constants on the acidity of the aqueous reaction system is evaluated. It can be shown that the 2-naphtholate-3,6-disulfonate trianion reacts 4 × 108–8 × 108 times faster than the 2-naphthol-3,6-disulfonate dianion. The rate constants of the six diazonium ions vary by more than four orders of magnitude. The logarithms of the rate constants of all comparable diazonium ions correlate linearly with 1H nmr chemical shifts of the respective unsubstituted heteroaromatic parent compounds. An analogous correlation was found for azo couplings with substituted benzenediazonium ions. Diazotization of heteroaromatic amines does not go to completion, rather to an equilibrium. It is shown therefore that in acidic coupling systems the azo compound is only the kinetically controlled product. The thermodynamic products are 1-nitroso-2-naphthol-3,6-disulfonic acid and the heteroaromatic amine.

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.

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