BazTech - Yadda

1

Katalityczne zgazowanie stężonych ścieków zaolejonych w warunkach nadkrytycznych

Gao Ming, Xu Junjie, Chu Zhuzhuan, Li Hui, Su Hao

Przemysł Chemiczny

|

2023

|

T. 102, nr 10

1008--1012

PL

Do oczyszczania ścieków zawierających olej (zawartość 4000 mg/L) zastosowano katalityczne zgazowanie w warunkach nadkrytycznych. Katalizator nano-CuO został przygotowany i użyty (2 mg/L) w obecności H₂O₂ (do 300 mg/L). Katalizator wykazał wysoką aktywność w degradacji olejów zawartych w ściekach. Przy pH 11 i w temp 445°C wartość ChZT ścieków zmniejszyła się o 95,6% po 25 min oczyszczania.

EN

The catalytic supercrit. gasification was used to purify the oil-containing wastewater (oil content 4000 mg/L). The nano-CuO catalyst was prepd. and used (2 mg/L) in presence of H₂O₂ (up to 300 mg/L). The catalyst showed high activity in degrdn. of the wastewater-contained oils. At pH 11 and temp. 445°C, the COD of the wastewater decreased by 95.6% after 25 min long treatment.

2

The extraordinary gravity of three atom 4π-components and 1,3-dienes to C20-nXn fullerenes; a new gate to the future of Nano technology

Siadati Seyyed Amir, Rezazadeh Solmaz

Scientiae Radices

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2022

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Vol. 1, Iss. 1

46--68

EN

A quick glance to the adsorption, sensing, and energy storage abilities of C₂₀ fullerene and its derivatives indicate that this small carbon cluster may have extraordinary properties which would make it a key part of the future of Nano actuators and Nano machines. For example, in the case of the gravity of three atom 4π-components (TACs) to these carbon cages, it should be noted that; the rate constants (K)s of the reaction of C₂₀ fullerene with 1,3-butadiene (Diels-Alder (DA) process), and with 2-furan nitrile oxide ([3+2] cycloaddition (32CA process)) are 2.51(10¹¹) M^-1 s^-1, and 1.4(10⁷) M^-1s^-1, respectively. However, the rate constant of the 32CAreaction between norbornadiene and 3,4-dihydro isoquinoline-N-oxide is about 2.56(10) M^-1 s^-1 (both by DFT and by experimental results). This simple comparison could show the extraordinary gravity of some TACs and dienes to C₂₀ fullerenes.

3

Preparation of Imidazolium 2,4,5-Trinitroimidazolate from Derivatives of Imidazole and Its Oxidation Under Nitration Conditions

Lian Pengbao, Hou Changming, Chen Lizhen, Xu Jianxin, Xu Zishuai, Wang Jianlong

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 4

379--392

EN

In this study, the nitration reactions of imidazole and its nitro derivatives with a mixture of 98% HNO₃ and 98% H₂SO₄ (or 15% SO₃ in H₂SO₄) were reinvestigated. When imidazole or 4(5)-nitroimidazole was nitrated with a mixture of 98% HNO₃ and 98% H₂SO₄ (or 15% SO₃ in H₂SO₄), only 4,5-dinitroimidazole was obtained. Imidazolium 2,4,5-trinitroimidazolate was prepared from 2-nitroimidazole or 2,4(5)-dinitroimidazole with a mixture of 98% HNO₃ and 98% H₂SO₄ (or 15% SO₃ in H₂SO₄); the highest yields were 57.8 and 62.8%, respectively. However, on increasing the reaction temperature, duration, amount of H₂SO₄ or HNO₃, the by-product ethanedioic acid was produced. A possible reaction mechanism for the formation of ethanedioic acid from 2,4,5-trinitroimidazole is suggested. The compounds 4,5-dinitroimidazole, imidazolium 2,4,5-trinitroimidazolate and ethanedioic acid were characterized by infrared spectroscopy, multinuclear ¹H and ¹³C NMR spectroscopy, and elemental analysis. The structures of 4,5-dinitroimidazole and ethanedioic acid were further confirmed by single-crystal X-ray diffraction.

4

Investigation of the reaction mechanism of blended fly ash and rice husk ash alkali-activated binders

Fernando Sarah, Gunasekara Chamila, Law David W., Nasvi M. C. M., Setunge Sujeeva, Dissanayake Ranjith, Ismail M. G. M. U.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e24, 2022

EN

This study investigates the influence of the chemical and physical properties of two abundantly available waste by-products in Sri Lanka, fly ash and rice husk ash (RHA) as precursor materials for the synthesis of alkali-activated binders. The suitability of the two types of fly ash and the replacement of fly ash by RHA (10% and 20% by weight of the binder content) were assessed. The study reports the development of compressive strength together with an in-depth analysis of the reaction mechanism of the blended RHA alkali-activated binders. The 100% fly ash mortar achieved the optimum compressive strength of 38.9 MPa at 28 days. Replacement of the fly ash with 10% and 20% RHA reduced the compressive strength by approximately 14% and 43%, respectively. The higher specific surface area of RHA and relatively higher unburnt carbon content in RHA were identified as the major factors influencing the low compressive strength obtained. Furthermore, the addition of RHA increases the reactive silica in the gel matrix and leads to an increase in the Si/Al ratio (3.70–3.89), which has a negative effect on the compressive strength. The difference in solubility rate of precursor fly ash and RHA negatively affect the formation of the gel matrix which is hypothesized as a further reason for the lower compressive strength observed in the RHA mixes.

5

Improved understanding of Sodium hydroxide concentration role and kinetic model of cryolite reactive extraction in cathode Spent Pot Linings

Tropenauer Blaž, Klinar Dušan, Golob Janvit

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 1

37--44

EN

Spent Pot Lining (SPL) cathode pot, waste from the aluminium smelting process needs detoxification from cyanides, washing out water-soluble salts and extraction of the cryolite (Na3AlF6) decomposition products to be recycled. Revealed cryolite decomposition mechanism with NaOH opens possibilities to explore its critical role in the reactive extraction process. Common Na+ ion from NaOH hinders the solubility of the product but also drives mass transfer to the reaction site. Reaction mass balance provides adequate liquid to solid ratio (L/S) and NaOH concentration range. A newly developed kinetic model based on Whitman film theory and NaOH mass flow enables prediction of the reaction time to decompose cryolite to a low enough level. Results show that the internal particle resistance to transport (1/ks) is 19 times larger than the external (1/kl) one and governs the whole process.

6

Kinetic Studies of Pt(IV) Chloride Complex Ions Reduction Reaction Using Potassium Formate

Wojnicki M., Żabiński P., Csapó Edit

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1135--1140

EN

In this paper, the kinetics of the platinum(IV) chloride complex ions reduction reaction was studied. It was shown that the mechanism exhibits autocatalytic character. The presence of metallic platinum in the system significantly increases the reaction rate. The influence of the initial concentration of precursor, reductant, ionic strength, initial concentration of the chloride ions as well as the temperature on the process rate was investigated. The activation energy was determined and is equal to 93.57 kJ/mol. Moreover, the obtained metallic phase was analyzed, and it was observed that it has a micrometric size.

7

Badanie wpływu inhibitorów procesu fotokatalitycznego na degradację wybranych leków sulfonamidowych

Adamek E., Baran W., Cholewiński M., Pelczar B.

Proceedings of ECOpole

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2018

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Vol. 12, No. 2

383--391

PL

Powszechnie przyjmuje się, że mechanizmy reakcji fotokatalitycznych przebiegających z udziałem substancji o podobnej budowie chemicznej również są podobne. Obserwowane różnice w szybkości tych reakcji tłumaczy się najczęściej różnicami w efektywności sorpcji substratu na powierzchni heterogenicznego katalizatora. W przypadku procesów fotokatalitycznych reakcje propagacji z udziałem rozkładanego substratu są poprzedzane inicjacją wolnych rodników. Drogi tych procesów mogą być różne, a ustalenie najbardziej prawdopodobnego przebiegu jest możliwe dzięki zastosowaniu selektywnych inhibitorów reakcji fotokatalitycznych. Celem badań była obserwacja wpływu kilku selektywnych inhibitorów (jodku sodu, izopropanolu i benzochinonu) na fotokatalityczną degradację sulfanilamidu i 8 jego pochodnych, a więc cząsteczek różniących się jedynie rodzajem podstawnika amidowego. Reakcję inicjowano promieniowaniem UVA w obecności TiO2-P25 jako fotokatalizatora. Stwierdzono, że mechanizmy degradacji sulfonamidów o podobnej budowie mogą być jednak różne i ponadto mogą ulegać istotnym zmianom w zależności od pH. Przykładowo, każdy z badanych wolnych rodników, niezależnie od rodzaju, powoduje rozkład sulfisoksazolu w środowisku kwaśnym. Fakt ten może mieć istotne znaczenie praktyczne, ponieważ wskazuje, że jest możliwe sterowanie selektywnością reakcji fotokatalitycznych wykorzystywanych do usuwania zanieczyszczeń ze środowiska wodnego.

EN

It is commonly assumed that the mechanisms of photocatalytic reactions of the compounds having a similar chemical structure are also similar. The observed differences in the reactions rate are most often explained by the difference in the sorption efficiency of substrates on a heterogeneous catalyst surface. In the photocatalytic processes, the free radicals generation is followed by the propagation reactions with the degraded substrates. The pathways of these processes may be different and the use of selective inhibitors allows to observe the reaction mechanism. The aim of our study was to observe the effect of selective inhibitors (i.e., sodium iodide, isopropanol and benzoquinone) on the photocatalytic degradation of sulfanilamide and its eight derivatives differing only in the nature of the amide substituent. The reaction was initiated by UVA irradiation in the presence of TiO2-P25 as a photocatalyst. It was found that the degradation mechanisms of sulfonamides having even a similar structure may be different and may be significantly affected by pH values. For example, regardless of the type of free radicals, they degrade sulfisoxazole in an acidic medium. This fact can have important practical meaning because it is likely possible to direct the selectivity of photocatalytic reactions during removal of contaminants from the aquatic environment.

8

Efficient sulfidization of lead oxide at high temperature using pyrite as vulcanizing reagent

Zheng Y.-X., Lv J.-F., Wang H., Wen S.-M., Huang L.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

270--277

EN

A sulfidization roasting-flotation process was usually viewed to be effective in treating the refractory oxide ore. In this paper, pyrite was proposed to be applied as a potential vulcanizing reagent to transform PbO or its surface to PbS based on feasibilities of technology and economy. The evolution process, phase and characteristics of crystal growth were investigated by TG, XRD and SEM-EDS, respectively, to interpret the interaction mechanism of lead oxide and pyrite at high temperature. It was found that the decomposition process of pyrite under argon atmosphere was a slow process of sulfur released from FeS2 to FexS, which made the process easier to be controlled. When PbO was introduced into the system, the initial solid-solid (PbO-FeS2) reaction and prevailing solid-gas (PbO-S2(g)) reaction occurred at about 500 °C and 700 °C, respectively. Combined with the SEM-EDS analyses results, the optimal temperature for the sulfidization of PbO should be in the range of 700-750 °C.

9

Effects of different Sn contents on formation of Ti2SnC by self-propagating high-temperature synthesis method in Ti-Sn-C and Ti-Sn-C-TiC systems

Sun H Y, Kong X, Sen W, Yi Z Z, Wang B S, Liu G Y

Materials Science Poland

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2014

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Vol. 32, No. 4

696--701

EN

Effect of different Sn contents on combustion synthesis of Ti2SnC was studied using elemental Ti, Sn, C and TiC powders as raw materials in the Ti–Sn–C and Ti–Sn–C–TiC system, in which the molar ratio of Ti/C was set as 2:1. The reaction mechanism for the formation of Ti2SnC was also investigated. The results showed that the amount of Ti2SnC in combustion products firstly increased with increasing of Sn content (0.6 to 0.8 mol), and then decreased with further increasing of Sn content (1.0 to 1.2 mol). Upon addition of 15 % TiC instead of Ti and C, the optimum addition of Sn decreased to 0.7 mol and a higher purity of Ti2SnC was obtained. The Ti2SnC powders were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

10

Electrochemical dissolution of synthetic heazlewoodite (Ni3S2)

Aromaa J.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 46

51-64

EN

The aim of the study was to examine the dissolution kinetics of synthetic heazlewoodite and the formation of elemental sulfur by electrochemical methods. Anodic polarisation curves, potentiostatic measurements and cyclic voltammetry were carried out in 1 N sulfuric acid at temperature 25°C. The anodic dissolution of heazlewoodite procceds in two stages. At potentials below 600 mV vs. SCE heazlewoodite is only converted to higher sulfides such as millerite NiS. At higher potential the reaction products dissolve forming first other sulfides and elemental sulfur and later other sulfides, elemental sulfur and sulfate. The percentage of sulfides in the reaction products was high even at high potentials. The formation of elemental sulfur was not seen to hinder dissolution of the sulfide. The part of sulfur oxidized to sulfate increased with increasing potential. Up to 900 mV only elemental sulfur was formed, at 1000 mV 10% of sulfur was oxidized to sulfate and at 1600 mV 90% of the sulfur was sulfate.

PL

Przedmiotem pracy były badania kinetyki roztwarzania syntetycznego hezelwudytu oraz tworzenia się siarki w tym procesie, z zastosowanie metod elektrochemicznych. Badania prowadzone były w 1 N kwasie siarkowym, w temperaturze 25°C, metodami: potencjostatyczną, krzywych polaryzacyjnych oraz woltamperometrii cyklicznej. Roztwarzanie anodowe hezelwudytu przebiego dwustopniowo. Przy potencjałach poniżej 600 mV hezelwudyt przechodzi w siarczki o wyższej zawartości siarki, na przykład mileryt (NiS). Przy wyższych potencjałach hezelwudyt ulega roztwarzaniu, tworząc siarczki o wyższej zawartości siarki i siarkę, a następnie siarczki o wyższej zawartości siarki, siarkę i siarczany, przy czym przy wyższych potencjałach obserwowano tworzenie się większej ilości siarczków o wyższej zawartości siarki. Nie zaobserwowano negatywnego wpływu tworzenia się siarki elementarnej na przebieg procesu roztwarzania. Ilość tworzących się siarczanów wzrasta wraz ze wzrostem potencjału. Poniżej potencjału 900 mV tworzy się siarka elementarna, przy potencjale 1000 mV 10% siarki ulega utlenieniu do siarczanów, a przy potencjale 1600 mV do siarczanów ulega utlenieniu aż 90% siarki.

11

Badania typu zdefektowania dominującego w disiarczku niklu NiS2

Grzesik Z., Mrowiec S.

Ochrona przed Korozją

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2010

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nr 11

564-566

PL

W celu określenia typu dominującego zdefektowania sieci krystalicznej NiS2, zbadano mechanizm powstawania tego siarczku stosując metodę markerów. Badania te przeprowadzono w zakresie temperatur 823-923 K przy prężności par siarki 103-104 Pa. Stwierdzono, że markery złota naniesione przed reakcją na powierzchnię fazy NiS znajdują się po zakończeniu procesu siarkowania w połowie grubości warstwy produktu reakcji (NiS2). Wynik ten oznacza, że dominujące zdefektowanie w badanym siarczku występuje w obrębie podsieci kationowej.

EN

In order to elucidate the predominant disorder in the crystalline lattice of NiS2, the mechanism of sulphidation of NiS has been studied using marker technique. Experiments have been carried out in the temperature range 823-923 K in sulphur vapors under pressure between 103-104 Pa. It has been found that gold markers deposited on the surface of NiS substrate have been found after sulphidation in the interior of the NiS2 product layer, just in the middle of the thickness of it. These results have demonstrated that predominant defects in NiS2 disulphide occur in the cation sublattice.

12

Autooxidation of leuco-Methylene Blue – the Role of the Methylene Blue Radicals and Reactive Oxygen Species

Katafias A., Koter S.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 6

1139-1146

EN

Autooxidation of leuco-Methylene Blue to the dye, Methylene Blue, was studied in the 1.9–7.8 pH range under a large molar excess of dioxygen dissolved in the reaction solution using electronic spectroscopy. The synproportionation of the substrate and the reaction product, yielding Methylene Blue radical, plays a key role in the over all redox process. Numerical simulation of the complicated kinetic curves shows that presence of this radical opens an effective reaction path for the autooxidation process and results in coupling of the reaction steps. Reactive oxygen species (HO2 ź /O2 ź - / and H2O2) formed in the examined system are not effective oxidants and do not affect the autooxidation kinetics under applied conditions.

13

Kinetics and Mechanism of the Nucleophilic Cleavage of Disulfide Bond in 2,2-Dithio-diimidazoles with Hydroxide Ions

Kurzawa J., Suszka A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1487-1494

EN

Kinetics of the cleavage of disulfide bond of dithiobisdisulfides of diimidazoles to their parent imidazoles by hydroxide ion have been investigated spectrophotometrically. Rate equation and other observations suggest that the nucleophilic attack of hydroxide ion on one of the sulfur atoms of disulfide bond is a rate limiting step. This process is accompanied by much slower, parallel reaction with water as a nucleophile. Hence the full kinetic equation for nucleophilic cleavage of 2,2 -dithio-diimidazoles in aqueous alkaline solutions is a two-term equation: –(d[RSSR]/dt) = k1[RSSR][OH–] + k2[RSSR][H2O], where k1 > k2. The mechanism of the reaction is proposed.

14

Azo dye degradation by high-energy irradiation: kinetics and mechanism of destruction

Takács E., Wojnárovits L., Pálfi T.

Nukleonika

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2007

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Vol. 52, nr 2

59-67

EN

The kinetics and mechanism of dye destruction is discussed on the example of Apollofix Red (AR-28) and Reactive Black 5 (RB-5) radiolysis in dilute aqueous solution. The dose dependence of colour disappearance is linear when the reactive intermediate reacts with the colour bearing part of the molecule causing destruction of the conjugation here with nearly 100% efficiency. In this case, spectrophotometry can be used to follow-up dye decomposition. Such a linear dependence was observed when hydrated electrons or hydrogen atoms reacted with the dye. However, in the case of hydroxyl radical reactions some coloured products form with absorption spectra very similar to those of the starting dye molecules. For that reason, spectrophotometric measurements give false results about the concentration of intact dye molecules. Analysis made by the HPLC (high-pressure liquid chromatography) method reveals logarithmic time dependence in agreement with a theoretical model developed.

15

Reaction mechanisms of alcohols on aluminum surfaces

Wiltord F., Martin J., Le Mogne T., Jarnias F., Querry M., Vergne P.

Tribologia

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2006

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nr 6

7-20

EN

The general aim of this work concerns the study of the lubricant/surface interaction mechanisms, such as those occurring during aluminum cold rolling in the presence of fatty alcohols. To improve the understanding of alcohol tribochemical reactions on an aluminum surface, friction tests followed by SIMS analyses were conducted. Deuterated alcohols were used to investigate the formation of bonds between the aluminum surface and alcohol molecules. The combination of SIMS analysis and the use of deuterated molecules have enabled us to propose a reaction mechanism between alcohols and the initial oxidized aluminum surface. This mechanism later affects the tribological behavior of the interface. In agreement with previous observations, we showed that a low steric size increases the number of acting molecules on the oxidized surface and that the alkyl chain length is of importance to protect the surface and hence reduce friction. These two key points can be easily explained by the proposed reaction pathway.

PL

Celem niniejszej pracy było zbadanie mechanizmów oddziaływań układu środek smarowy/powierzchnia, które między innymi mają miejsce podczas walcowania na zimno aluminium w obecności alkoholi tłuszczowych. Produkty tribochemicznych reakcji alkoholi, zachodzące na powierzchni aluminium, badano za pomocą spektrometrii masowej jonów wtórnych (SIMS). Aby zbadać tworzenie się wiązań pomiędzy powierzchnią aluminiową a cząsteczkami alkoholu, zastosowano deuterowane alkohole. Połączenie techniki SIMS oraz deuterowanych cząsteczek pozwoliło zaproponować mechanizm reakcji alkoholi i utlenionej powierzchni aluminium. Mechanizm ten wyjaśnia wpływ alkoholi na tribologiczne zachowanie się warstw wierzchnich współpracujących elementów. Zgodnie z poczynionymi wcześniej obserwacjami wykazano, że mniejszy rozmiar przeszkody sterycznej zwiększa liczbę oddziałujących cząsteczek z utlenioną powierzchnią, a także, że długość łańcucha alkilowego pełni istotną rolę w ochronie powierzchni i tym samym redukcji tarcia. Te dwa kluczowe aspekty można łatwo wytłumaczyć za pomocą zaproponowanych procesów tribochemicznych.

16

Displacement of CO from Ni(CO)4 by Diphosphine Disulfide Derivatives via a Photochemical Reaction

Aqra F., Jamhour R.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 6

983-987

EN

A series of compounds with formulas [Ni(CO)2R4P2S2] and [Ni2(Co)6-mi-R4P2S2] (R = Me, Et, Prn, Bun and Ph) have been prepared photochemically by the reaction of Ni(CO)4 with R2PSPSR2 using a 400 Wmedium pressure mercury lamp through a quartz-walled immersion well reactor. They were characterized by elemental analyses, IR and 31PNMR spectroscopy. The results reveal, that the disphosphine disulfide ligands show disubstitution and, thus, act as a bidentate species or monosubstitution and so act as a bridging ligand.

17

CO oxidation over the Au catalyst - the state of art

Dobrosz I., Kocemba I., Rynkowski J.M.

Polish Journal of Chemical Technology

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2005

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Vol. 7, nr 3

27-34

EN

Gold catalysts have recently been attracting rapidly growing interest due to their potential applications to many reactions, of both industrial and environmental importance. The oxidation of CO is one of the significant reactions. This article presents an overview of the recent study on more important factors that determine the catalytic activity of supported gold catalysts in CO oxidation reaction, with an emphasis on those that provide some information on the underlying chemistry. The criteria that must be met before high catalytic activity can be obtained, and the extreme sensitivity of the final catalyst to all stages of its preparation and treatment before use, are summarized. The influence of the preparation method, the size of the gold particle, the nature of the support and the effect of chloride on the catalysts performance as well as a conclusive analysis of the mechanism of CO oxidation over supported gold catalysts were presented.

18

Wpływ stałego pola magnetycznego na kinetykę i mechanizmy reakcji redoks

Zieliński M., Kupis J., Miękoś E.

LAB Laboratoria, Aparatura, Badania

|

2005

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R. 10, nr 5

16-20

19

Kinetyczne przesłanki mechanizmu kondensacji Knoevenagela

Bednarz S., Bogdał D.

Czasopismo Techniczne. Chemia

|

2004

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R. 101, z. 1-Ch

3-12

PL

Badano kinetykę reakcji kondensacji Knoevenagela aldehydu salicylowego z malonianem dietylu, katalizowaną 4-piperydynopiperydyną w toluenie jako rozpuszczalniku. Zaproponowano model kinetyzacji reakcji.

EN

The kinetic of the Knoevenagel condensation of salicylaldehyde with diethylmalonate in the presence of 4-piperidinopiperidyne as a catalyst in toluene as a solvent has been studied. The reaction mechanism was proposed and kinetic model was numerically verified.

20

Structure and Rearrangement of Ring Substituted N0Methyl-N-phenylnitramines

Daszkiewicz Z., Zaleski J., Nowakowska E. M., Kyzioł J. B.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 8

1113-1125

EN

The mechanism of the acid catalyzed nitramine rearrangement must account for the unusual sensitivity of the reaction of N-methyl-N-phenylnitramine derivatives to the ring substituents. Spectral analyses indicate the lack of interaction between the nitramino group and the second substituent through the aromatic ring. X-ray analyses confirm the spectral data: there is no conjugation between the aromatic and nitramine sextets of _-electrons. X-ray structural data also indicate that the nitramino group cannot behave as the basic centre. A reconsideration of the rearrangement rate constants of the series of ring substituted N-methyl-N-phenylnitramines lead to the conclusion that migration of the N-nitro group precedes protonation. The influence of the substituents on the reaction rates is determined by their influence on the basicity of the imino nitrogen in an intermediate. The CIDNP effect, observed in the rearrangement, results from the transformation of mobile nitrito group into the stable nitro substituent.