Structures of the covalent hydrates and products of acidic hydrolysis of rheumycin and fervenulin

It is shown that pyrimido[5,4-e]-1,2,4-triazinediones are hydrated at the N(₄)-C(_4a) bond in aqueous acidic media. The equilibrium constants of these processes were measured by PMR spectroscopy. The structure of the covalent adduct of fervenulin was established by x-ray diffraction analysis. Formic, 5-diazo-3-methylbarbituric, and methylparabanic acids were identified among the products of destruction of the hydrates in acidic media.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1654–1660, December, 1988.     

The alkaline hydrolysis of nylons and terylene

Summary The acid hydrolysis of nylons has been carried out quantitatively byHaslam ³ andSchroeder ⁴ using hydrochloric acid solutions. These methods require several hours for complete hydrolysis. The alkaline hydrolysis of nylon 6 has been carried out using barium hydroxide solutions in an autoclave for 24 hours⁵. Although the potassium hydroxide method described is not quantitative, the hydrolysis, isolation, and characterisation of the products can be carried out in 1 to 3 hours.

---

Zusammenfassung Die saure Hydrolyse von Nylon wurde vonHaslam ³ undSchroeder ⁴ mit Salzsäurelösungen quantitativ durchgeführt. Diese Verfahren beanspruchen für die vollständige Hydrolyse mehrere Stunden. Die alkalische Hydrolyse von Nylon 6 wurde mit Bariumhydroxidlösung in einem Autoklaven in 24 Stunden durchgeführt⁵. Obwohl das beschriebene Verfahren mit Kalilauge nicht quantitativ ist, kann man die Hydrolyse sowie die Isolierung und Charakterisierung der dabei erhaltenen Produkte in 1 bis 3 Stunden ausführen.

---

Résumé Haslam ³ etSchroeder ⁴ ont effectué l'hydrolyse acide quantitative des nylons en utilisant des solutions d'acide chlorhydrique. Ces méthodes exigent plusieurs heures pour l'hydrolyse complète. On a réalisé l'hydrolyse alcaline du nylon 6 en utilisant des solutions d'hydroxyde de baryum, pendant 24 heures dans une autoclave. Bien que la méthode à l'hydroxyde de potassium décrite ne soit pas quantitative, l'hydrolyse, l'isolement et la caractérisation des produits peuvent s'effectuer en 1 à 3 heures.

---

---

The author wishes to express his gratitude to Dr.J. Haslam for helpful discussions and to I. C. I., Ltd., Courtaulds, Ltd., and G. Slack, Ltd., for the gift of samples.     

The alkaline hydrolysis of 4-methoxycoumarin

The aqueous alkaline hydrolysis of 4-methoxycoumarin occurs in two stages. In the first, the lactone ring is opened at a rate directly proportional to the concentration of base. In the second, the methoxy group is replaced by an unusual route that depends upon the presence of an $\text{un}$ionised phenolic hydroxy group and is therefore inversely proportional to the concentration of base. Methanolysis by methoxide ion in methanol occurs primarily at position 4 and replaces the methoxy group before the ring is opened; the difference from the aqueous hydrolysis is ascribed to solvent effects.     

The alkaline hydrolysis of flavonoid glycosides

Conclusions 1. The alkaline hydrolysis of flavonoid glycosides has been studied.2. In an alkaline medium 3-glycosides, C-glycosides, and biosides having 1, 2 bonds between the sugars are stable.3. The difference in the stabilities of the glycosides to alkalis can be used in studying flavonoid O-diglycosides, O-biosides with different positions of the bond, O,C-diglycosides, and O,C-biosides.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 366–369, 1969     

Kinetics of the acid and alkaline hydrolysis of Monofluorophosphite

The kinetics of the acid and alkaline hydrolysis of monoflorophosphorous acid has been studied by P-31 NMR and static pH titration over a wide temperature range. The acid catalyzed hydrolysis has a rate constant at 25°C equal to 0.35 dm³ mol^?1 s^?1 and an activation energy of 53 kJ while the alkaline hydrolysis has a rate constant of 4.6 dm³ mol^?1 s^?1 and an activation energy of 42 kJ. When the hydrogen in this compound is replaced by either fluorine or a hydroxyl group, the rates of reaction decrease by two orders of magnitude. © 1994 John Wiley & Sons, Inc.     

A new synthesis of fervenulin 4-oxide

The reaction of 1,3-dimethyl-6-hydrazino-5-nitrosouracil (1) with Vilsmeier reagent (dimethylformamide-phosphorus oxychloride) afforded fervenulin 4-oxide (II) in good yield.     

Synthesis and alkaline hydrolysis of (pentafluoroethyl)imidazoles

Photochemical ring substitution of the N-trifluoroacetyl derivatives of histamine and of L-histidine methyl ester by pentafluoroethyl radical provides the corresponding 2- and 4-pentafluoroethylated products in yields of 19% and 27%, respectively. Alkaline hydrolysis converts the 2-pentafluoroethyl group to trifluoroacetyl. The reaction mechanism, involving a diazafulvene intermediate, is analogous to that elucidated for (trifluoromethyl)imidazoles; however, the pentafluoroethyl group is markedly more reactive to hydrolysis than the trifluoromethyl group. For imidazole derivatives, the ratio of reactivities is 75 at C-2 and 40 at C-4. The hydrolysis of 4-(pentafluoroethyl)histamine affords the bicyclic product, 4-(trifluoromethyl)-6,7-dihydro-1H-imidazo[4,5-c]-pyridine in 65.4% yield.     

An expedient synthesis of an isofervenulin analogue

An efficient approach has been developed for the synthesis of an isofervenulin analogue 1 employing a one‐pot condensation‐substitution reaction of a chlorocarboethoxytriazine (electrophile) with a urea (nucleophile). The resulting cyclization reaction resulted in the synthesis of a pyrimido‐heterocycle in good yield in either acidic or basic media. The former was assisted by utilizing trimethylsilyl chloride.     

Kinetics of the alkaline hydrolysis of flavonoid glycosides

Summary 1. In a study of the kinetics of the alkaline hydrolysis of flavone glycosides it has been found that derivatives of 3,3,4,5,7-pentahydroxyflavone hydrolyze faster than derivatives of 3,4,5,7-tetrahydroxyflavone and of 3,4,5,7-tetrahydroxy-3-methoxyflavone.2. In the hydrolysis of diglycosides of 3,3,4,5,7-pentahydroxyflavones the maximum amount of intermediate product is formed after 2 min (3,4,5,7-tetrahydroxyflavone glycoside), and in the case of 3,4,5,7-tetrahydroxy-3-methoxyflavone glycosides after 120–150 min.I. V. Kutateladze Institute of Pharmacochemistry, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 646–649, September–October, 1977.     

Kinetics of the alkaline hydrolysis of alkoxyfluoroborate anions

The kinetics of the alkaline hydrolysis of BF₃OR^– anions (R=C₂H₅, C₃H₇) have been investigated. It has been shown that the reaction mechanism includes the solvolytic dissociation of a B-F bond and that the processes resulting in the replacement of the first fluoride ion act as the rate-limiting step. The influence of the electron-donor ability of the substituents on the rate of processes has been studied, and the reactivity of alkoxyfluoroborates has been compared with the data from quantum-chemical calculations of the distribution of the electron density in the anions in the framework of Dewar's MNDO method with complete optimization of the structural parameters.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 1, pp. 123–126, January–February, 1989.We thank Yu. B. Vysotskii for a fruitful discussion of the results.     

Theoretical studies on the alkaline hydrolysis of N-Methylcarbamates

The reaction mechanisms of the alkaline hydrolysis of N-methylcarbamates were studied using the AM1 method by assuming two possible pathways: (1) nucleophilic attack of hydroxide ion on the carbonyl carbon to give a tetrahedral complex followed by its breakdown to carbamic acid (B_AC2); and (2) proton abstraction by hydroxide ion at the nitrogen atom followed by elimination of the alkoxide ion to form N-methyl isocyanate (E1cB). Reaction coordinate analysis showed that the reaction mechanism is determined by both the stability of an intermediate and the energy barrier for elimination.     

The kinetics and mechanism of alkaline hydrolysis of N-substituted phthalimides

The aqueous cleavage of N-(2-bromoethyl)phthalimide (NBEPH), N-(3-bromopropyl)phthalimide (NBPPH), and N-carbethoxyphthalimide (NCPH) have been studied within the [ōH] range of 5 × 10^?4 M to 2 × 10^?3 M, pH range of 8.82 to 10.62 and 8.06 to 8.66, respectively. The observed pseudo-first-order rate constants, k_obs, reveal a linear relationship with [ōH] with essentially zero intercept. The alkaline hydrolysis of N-(hydroxymethyl)phthalimide (NHMPH) has been studied within the [ōH] range of 5.64 × 10^?6 M to 2.0 M. The [OH]-rate profile reveals that both ionized and nonionized NHMPH are reactive toward ōH. The second-order rate constant, k_OH, for the reaction of ōH with non-ionized NHMPH is ca. 10⁴ times larger than that with ionized NHMPH. The values of k_OH obtained for NBEPH, NBPPH, NCPH, and nonionized NHMPH show a reasonable linear relationship with Taft substituent constants, and the slope (ρ*) of the plot is 1.01 ± 0.10. The low value of ρ* of 1.01 is attributed to nucleophilic attack as the rate-limiting. The k_OH value for ionized NHMPH reveals nearly 10³-fold negative deviation from the linear Taft plot.     

Formation of aminotetrazines and triazoles by alkaline hydrolysis of thiosemicarbazide

3,6-Diamino-1,2,4,5-tetrazine is formed by alkaline hydrolysis of thiosemicarbazide in the presence of oxidizing agents (oxygen, silver ions). 3,4,5-Triamino-1, 2,4-triazole is formed when the temperature is raised and when oxidizing agents are absent.