Wyniki wyszukiwania - BazTech

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Modelowanie właściwosci wiązań wodorowych na przykładzie kompleksów układ amidowy - woda

Rzepiela Kacper, Buczek Aneta, Kupka Teobald, Kar Tapas, Broda Małgorzta A.

Wiadomości Chemiczne

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2023

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[Z] 77, 7-8

629--645

EN

The energy and structure of intermolecular hydrogen bonds between water molecule and N-methylamide (NMA) or uracil (U) are discussed on the basis of DFT calculations. Theoretical methods are applied to calculate properties of cis- and trans- NMA complexes with one water molecule. Subsequently, H-bonds in six uracil – water complexes are analyzed. The influence of dispersion interactions and the polar environment on the hydrogen bond energy was analyzed. Results obtained by B3LYP functional with and without Grimme D3 dispersion correction indicate that dispersion interaction plays a significant role in an association process. In addition, the polar solvent reduces the hydrogen bond energy and this reduction is directly proportional to the hydrogen bond energy.

2

Powstawanie ubocznych produktów chlorowania wody zawierającej uracyl i jego pochodne

Kucharski M.

Ochrona Środowiska

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2001

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nr 4

23-25

EN

Investigated were the reactions that occur in the water between the free available chlorine (FAC) and uracil over the FAC/uracil ratio varying from 0.25 to 10 mol/mol and pH ranging from 6 to 9. The course of the reaction was related to the pH of the water, as well as to the presence of bromide, iodide and fluoride ions. It was found that when the FAC/uracil ratio was low, 5-chlorouracil was the only chlorination product. At FAC/uracil ratios greater than 10, dichlorouracil and nitrogen trichloride were present in the chlorination products, whereas chlorouracil was absent. In the presence of iodides and bromides in the investigated water, chlorination also accounted for the formation of 5-iodouracil and 5-bromouracil.

3

Powstanie niebezpiecznych związków podczas chlorowania wody zawierającej uracyl

Kucharski M.

Zeszyty Naukowe Politechniki Białostockiej. Matematyka, Fizyka, Chemia

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1998

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Z. 18

9-19

PL

W pracy przedstawiono wyniki badań nad reakcją przebiegającą w wodzie między chlorem (wodnym chlorem pozostałym), a uracylem w zakresie stosunków molowych; wolny chlor pozostały: uracyl (WChP : Ur) wynoszącym od 0,25 do 10 mol/mol. Badano także wpływ pH oraz obecność jonów bromkowych, jodkowych i fluorkowych na przebieg tej reakcji. Ustalono, że przy niskim współczynniku WChP : Ur jedynym produktem chlorowania jest 5-chlorouracyl, a przy wysokim współczynniku (powyżej 10) brak jest chlorouracylu w produktach chlorowania. Obecność w badanych roztworach bromków i jodków powoduje powstawanie 5-bromo- i 5-jodouracylu.

EN

The object of the research was reaction between free available chloride (FAC) and (Ur) over the range FAC to uracil ration between 0,25 and 10 mol/mol and over pH range of 6-9. Determined that, at low FAC/uracil rations chlorination product was only 5-chlorouracil, a the higher FAC/uracil rations inproducts were dichlorouracil and nitrogen trichloride. In presense of added iodide or bromide, the chlorination leads to produce in addition to 5-chlorouracil, important quantities of 5-iodouracil and 5-bromouracil respectively.

4

Metody syntezy siarkowych pochodnych zasad pirymidynowych

Nowakowska Z., Wyrzykiewicz E.

Wiadomości Chemiczne

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1998

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[Z] 52, 5-6

449-466

EN

Uracil thio-derivatives have become to play increasingly important roles in biology and medicine. Numerous sulphur-substituted pyrimidines have found applications as clinically useful drugs. Thiouracils have recently been the subject of considerable interest as they inhibit hyperthyroidism in man [1, 2], have been isolated from E. Coli tRNA [3], and inhibit virus [4] and bacterial growth [5] by causing alterations [6] in protein synthesis. Thiouracils are also of interest because of mutagenic [7], anticancer and antithyroid activity [8], kidney stone formation inhibition [9] and antidote properties for mercury poisoning . Two of them, 2-thiouracil and 6-propyl-2-thiouracil, exhibit marked affinities for melanin-producing tissue in vitro and a similar affinity in vivo, where they presumably act as false precursors for melanin [10, 11]. Boron-containing derivatives of thiouracils [12-14] containing a dihydroxyboryl (or 1-o-carboranylalkyl) group in the 5-position are very important because of their potential applications for BNCT. Human immunodeficiency virus type 1 (HIV-1) is the causative agent of acquired immunodeficiency syndrome (AIDS), which is one of the world's most serious health problems. Since the discovery of the acyclic 6-substituted uridine derivative 1-[(2-hydroxyethoxy0methyl]-6-(phenythio)-thymine (HEPT) as a novel lead for specific anti-HIV-1 agents [15], a number of HEPT analogs have been synthesized to increase its potency [16-18]. The studies of the structure-activity relationships of HEPT analogs indicated that replacement of the 2-oxo function with a thine function potentiated their anti-HIV-1 activity [16, 19, 20]. Therofore the synthesis of thio-substituted pyrimidine bases and their derivatives appears to be a challenge for organic chemists. The methods of preparation of these compounds have been reviewed.