Old Password. New Password. Password Changed Successfully Your password has been changed. Returning user. Request Username Can't sign in? Forgot your username? Ionization followed by thiocyanate ion attack. Direct bimolecular displacement of thiocyanate. Cycloalkyl thiocyanates. Bridged compounds. Monocyclic compounds. Acy 1 t hiocyana t es A ryl t hiocyana tes 4-Toluenesulphonate ;is ;I leaving group. Ally1 thiocyanntes.
Photo-inducei Thiocyanate-Isotliiocyanate Isomerization. Organic Thiocyanates as Trifunctional Electrophiles. Interpretation of product analyses. Mechanism of reaction at cyanide carbon atom. Competition between aryl carbon and cyanide carbon. Substituent effects. Reaction a t thiocytnLite sulpl- :. Thermal Cyano t e-Isocyanate Isomertzn tion B.
http://www.cantinesanpancrazio.it/components/pyfuwyn/630-come-localizzare.php Photo-induce-i Cyannte-1socyan:ite Isomerization. Organic Cyanates as Trifunctional Electrophiles. Addition Reactions of Cyanntes and lsocyanates. Addition of alcohols. Metallic catalysis in addition reactions of isocyanates c. Cycloaddition to isocyanates. Diverse reactions of cyanates and related compounds have been studied in varying detail and at varying stages in the development of current understanding of organic reaction mechanisms. This review does not attempt to treat all, or even most.
Reactions of thio- cyanatcs and isothiocyanntes have been described first and in greater detail than those of their oxygen analogues because their lower reactivity has enabled their reactions within the chosen categories to be studied more systematically and extensively, with the possible exception that the i n d u s t r i a I I y- i ni port ant add it i o n react io 11s of i so c y a n a t es have at tract ed special attention.
Since the terms basicity and nucleophilicity.
In Swain and Scott' recommended that the term 'basicity' be used for equilibrium properties of a base. Basicity and nucleophilicity towards carbon may be illustrated with reference to the following biniolecular reactions:.
Since relative nucleophilicities measure reaction rates towards the one substrate, and relative basicities reflect reaction rates towards different substrates. The nitrogen ittoni of the SCN group is more basic towards carbon t h a n is the sulphur atom'. This enables alkyl.
The sodium salt was obtained for NMR by titrating to pH 8. However, itwas evident that substantial decomposition had occurred. Although complicated byinterference, the following resonance signals were considered characteristic of the productSMPC. Dicyc]ohexylcarbodiimide mg,1. Thesuspension was filtered, the filtrate added to an aqueous solution 3 mL of glycine The reaction was concentrated under vacuum to remove dioxane, extracted basic with ethylacetate 2 x 10 mL , adjusted to acidic pH with 4.
TLC,ether:acetic acid HF was removed under vacuum to afford the product as an insoluble waxy solidin anisole. Theresulting solution was adjusted to pH 9. The reaction was concentrated to dryness under vacuum, the resulting residuewashed with ether, taken up in H20 2 mL and applied to an Amberlite XAD-2 column 15 x2. The reaction was concentrated to an oil in vacuuo and extractedwith ethyl acetate.
Biological experiments5. In vivo xenobiotic metabolism5. Anaiyticalprocedures are detailed below. Urine samples were taken around the mid-point of theinfusion period i. Other drugs used in concomitant medicationincluded combinations of carbamazepine, dexamethasone, diphenhydramine, furosemide,ondansetron, phenytoin and warfarin. Metabolism of nitrosoureas and formamids in Sprague Dawley rats5. All xenobiotic treatments were delivered by intraperitoneal injection except NCEC which wasadministered by injection into the tail vein.
Analysis was conducted on the pooled biological fluid for all studies with oneexception. For quantitative metabolic profiling of CCNU in rats, urine samples from each offour dosed animals were individually analyzed. Urine samples were collected from rats housed in stainless steel metabolism cages withfree access to food and water. Urine collected before xenobiotic treatment served as acontrol. Bile was collected from the cannulated bile duct of the rat. Rats were anesthetized byintraperitoneal injection of urethane 1.
After anesthesia was induced ca 30 mm an incision of 3 cm was made on theventral surface of the animal left of the abdominal mid-line toward the diaphragm. Theintestines were displaced, the portion of the bile duct at the junction with the duodenumlocated and surrounding tissue gently removed with cotton wool.
A puncture was made intothe duodenum with a 25G1 needle to access the bile duct. The displaced intestines were relocated into the63abdominal cavity and the incision closed with interrupted sutures. Depending on theexperiment, bile samples were collected from 4 to 18 h post-dose and pooled for analysis. Where possible, bile collected before xenobiotic administration served as control, otherwisethe bile of rats dosed with the solvent vehicle was used for this purpose.
Priorto analysis, samples were centrifuged 13, g, 15 mm, Micro Centrifuge to pelletparticulate matter. In the initial studies on CCNU metabolism, rats were dosed i. Urine and bile samples 5 mL wereadjusted to pH 5.
Sampleswere extracted with ether, the organic extract discarded, the aqueous fraction concentrated todryness and then reconstituted in methanol iL. The flow rate was 0. Urinary metabolic profiling of CCNU in humans was performed on one patient 9 A 5 mL aliquot of the urine was prepared and analyzed as described above. For the purification of GSH conjugates from bile, the mobile phase consisted of 2.
The flow rate was 1. Metabolism of CCNU in rats and humans. Two IlL aliquots of urine from each rat and from each of two patients onchemotherapy and were analyzed for CCNU metabolites. Dilutions of the stock solutions intoa final volume of IlL with distilled water were used to prepare standards of the followingconcentrations: Aliquots IlL of urine samples and standard solutions were mixed65with 50 pL Metabolism of BCNU and 2-chioroethyl isocyanate in rats.
Urine and bile samples 5 mL were extractedwith ether, the organic extract discarded, the aqueous fraction concentrated to dryness andthen reconstituted in methanol tL. Metabolites were purified by HPLC using anisocratic delivery of 1. Metabolism of BCNU in humans. For quantitative analyses, the standard curve for the metabolite NCEC was prepared froma stock solution of the synthetic standard in 0.
Appropriate volumes of stocksolution, spiked with 75 jiL The urine aliquot was diluted with 25 jiL distilled water spiked with 75!. A 90IlL aliquot of bile was mixed with 10 IlL 1. Metabolism ofNFA in rats. Subsequent to urine collection, rats were anesthetized and their bile ducts cannulated. Immediately after cannulation, animals were dosed for a second time as described above andbile collected for 4 h over sodium acetate buffer 1. Bile and urine samples 2 mL were extracted with ethyl acetate 4 x 3 mL and theaqueous fractions applied to a column of XAD-2 resin 7 x 1.
The column was washedwith water 30 mL , and dried with air.