Raney Nickel Desulfurization Research Articles

Structure and Reactivity of Spruce Mechanical Pulp Lignins Part I. Bleaching and Photoyellowing ofin situLignins

ABSTRACT This paper reports the structural investigation of a series of in situ spruce lignins in wood, thermomechanical pulp (TMP) and the corresponding bleached (BTMP) and photoyellowed (YBTMP) samples. This was achieved by using an original two-step degradative technique, thioacidolysis followed by Raney nickel desulfuration. The determination of thioacidolysis monomeric and dimeric products allowed an estimate of various lignin building units and interunit bonds, respectively. It was observed that the thermomechanical and bleaching treatments did not affect spruce lignin structure to an appreciable extent. On the contrary, the photoyellowing treatment caused marked structural changes in lignin, particularly when run in severe conditions. These changes were essentially a decrease in the amount of β-O-4 and β-1 interunit bonds and a relative increase in catechol units and in vanillin end-groups.

Release and characterization of bound benomyl and carbendazim metabolites in animal tissues via Raney nickel desulfurization and acid dehydration

Release and characterization of bound benomyl and carbendazim metabolites in animal tissues via Raney nickel desulfurization and acid dehydration

Synthetic Applications of 2-(1,3-Dithian-2-yl)indoles. III. A New Route to Tetracyclic [ABCD] Intermediates in the Synthesis of Aspidosperma Indole Alkaloids

The synthesis of tetracyclic ABCD framework of Aspidosperma alkaloids has been achieved via allylamine-enamine isomerization using (Ph 3 P) 3 RhCI in hot aqueous acetonitrile of the 1,2,5,6-tetrahydro-3-(indolylethyl)-pyridine (13) which in turn was obtained by Raney nickel desulfurization of the corresponding 2-(1,3-dithian-2-yl)indole (5a)

Prenylated Proteins: the Structure of the Isoprenoid Group

The mevalonate-derived portion of a prenylated protein from Chinese hamster ovary cells has been established as diterpenoid (C20). This group is linked to a carboxyl-terminal cysteine as a thioether. It was removed from the protein by hydrazinolysis followed by Raney nickel desulfurization, and the resulting hydrocarbon fraction was analyzed by gas chromatography-mass spectrometry.

Depletion of mitochondrial coenzyme A and glutathione by 4-dimethylaminophenol and formation of mixed thioethers

4-Dimethylaminophenol (DMAP), an antidote in cyanide poisoning, has been shown to produce kidney lesions in rats, to damage isolated rat kidney tubules and to impair mitochondrial functions as already described for 4-aminophenol. Since DMAP upon oxidation forms bis- and trissubstituted thioethers with GSH, it was anticipated that mitochondrial toxicity of DMAP might result from CoA depletion. In a model reaction DMAP was oxidized by oxyhemoglobin in the presence of CoA and GSH resulting in formation of tris-(CoA-S-yl)-DMAP, tris-(GSH-S-yl)-DMAP and two mixed thioethers, namely, (CoA-S-yl)-bis-(GSH-S-yl)-DMAP and (GSH-S-yl)-bis-(CoA-S-yl)-DMAP. The compounds were isolated by HPLC and identified spectroscopically, by amino acid analysis and Raney-Nickel desulfuration. Rat liver mitochondria (5 mg protein/ml) incubated under state IV conditions with 20 and 50 μM DMAP were depleted of GSH and total coenzyme A with formation of GSSG and the above-mentioned thioethers which were quantified by isotope dilution techniques using [ 14C]-labelled DMAP and the isolated, inactive thioethers. The results confirm earlier suggestions that part of the cytotoxicity of DMAP may result from depletion of vital mitochondrial thiols, particularly CoA. Since 4-aminophenol reacts analogously, similar cytotoxic effects can be expected from compounds which on (aut)oxidation form quinoid systems capable of 1.4-addition reactions with nucleophilic thiols.

ChemInform Abstract: Synthesis and Reductive Desulfurization of Crown Ethers Containing Thiophene Subunit.

Crown ethers containing 3,4-thiophenediyl and 3,4-thiophenediylbis(methylene) subunits as a ring constituent were prepared starting from 2,5-bis(ethoxycarbonyl)-3,4-thiophenediol and 2,5-dichloro-3,4-bis(chloromethyl)thiophene, respectively. A Raney nickel desulfurization of the thiophene-containing crown ethers afforded crown ethers having two adjacent side chains, such as a methyl or ethoxycarbonylmethyl group. The extraction ability of these crown ethers towards alkali metal cations was also examined by the solvent extraction method.

Synthesis and Reductive Desulfurization of Crown Ethers Containing Thiophene Subunit

Abstract Crown ethers containing 3,4-thiophenediyl and 3,4-thiophenediylbis(methylene) subunits as a ring constituent were prepared starting from 2,5-bis(ethoxycarbonyl)-3,4-thiophenediol and 2,5-dichloro-3,4-bis(chloromethyl)thiophene, respectively. A Raney nickel desulfurization of the thiophene-containing crown ethers afforded crown ethers having two adjacent side chains, such as a methyl or ethoxycarbonylmethyl group. The extraction ability of these crown ethers towards alkali metal cations was also examined by the solvent extraction method.

ChemInform Abstract: Thiazoles in Organic Synthesis. Novel Syntheses of Menthanes and Eremophilanes.

ChemInformVolume 19, Issue 44 Natural Products ChemInform Abstract: Thiazoles in Organic Synthesis. Novel Syntheses of Menthanes and Eremophilanes. P. A. JACOBI, P. A. JACOBI Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorM. EGBERTSON, M. EGBERTSON Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorR. F. FRECHETTE, R. F. FRECHETTE Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorC. K. MIAO, C. K. MIAO Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorK. T. WEISS, K. T. WEISS Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this author P. A. JACOBI, P. A. JACOBI Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorM. EGBERTSON, M. EGBERTSON Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorR. F. FRECHETTE, R. F. FRECHETTE Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorC. K. MIAO, C. K. MIAO Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this authorK. T. WEISS, K. T. WEISS Hall-Atwater Lab., Wesleyan Univ., Middletown, CT 06459, USASearch for more papers by this author First published: November 1, 1988 https://doi.org/10.1002/chin.198844303Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume19, Issue44November 1, 1988 RelatedInformation

Thiazoles in organic synthesis. Novel syntheses of menthanes and eremophilanes

Acetylcnic thiazoles of proper design have been shown to undergo an intramolecular Diels-Alder reaction leading to fused-ring thiophene derivatives. When appropriately substituted, these latter materials can be readily converted to terpenes of the menthane and eremophilane class by Raney-nickel desulfurization

Synthesis of 1-(2-Deoxy-β-D-ribofuranosyl)benzimidazole via Cyclonucleosides

Abstract Starting from 2-chlorobenzimidazole and 1-O-acetyl-2,3,5-tri-O-benzoylribofuranose a β-D-ribonucleoside of 2-chlorobenzimidazole was obtained using Vorbrüggen's procedure. This compound was derivatized to a 2,2′-S-cyclonucleoside via 2′-O-tosylation and thiourea treatment. The cyclonucleoside was converted to 1-(2-deoxy-β-D-ribo-furanosyl) benzimidazole by Raney nickel desulfurization.

Nucleoside complexing. A 13C NMR spectroscopic investigation of the metal binding sites in 7-methylguanosine, 7-methylinosine and some related new synthetic betains

Once deprotonated, both the N1 and O6 positions of 6-oxopurine nucleosides become important metal binding sites. In a continuation of our studies of metal binding to 6-oxopurines alkylated at N7 and deprotonated at N1, we have carried out a 13C NMR spectroscopic study of the binding of various metal species including hard metal species (Sr, Ba, La, Pr), intermediate metal species (Zn, Cd, Pb), and soft metal species (Pt, Hg). A detailed study was not possible with HgCl 2 since mercuration occurred readily at C8. The 13C NMR shift patterns for the O6 resonance of 7-methylguanosine, 7-methylinosine, 2-dimethylamino-7,9-dimethylhypoxanthinium betain, 2-diethylamino-7-methyl-9-propylhypoxanthinium and betain and ethylamino and 6 thio analogs of the latter betain suggest that metal species of intermediate ‘softness’ prefer endocyclic N1 binding over exocyclic O6 a larger extent than they prefer endocyclic N3 binding over exocyclic O2 binding in cytosine derivatives. Most dramatically, the presence of a dialkylamino group ortho to the endocyclic binding site does not appear to prevent N binding in the betains whereas such binding is greatly, if not completely, prevented to cytosine derivatives. In particular, the complex cis-[Pt(Me 2SO) 2Cl 2] forms a complex with 2-dimethylamino-7,9-dimethyl-hypoxanthinium betain with an upfield shift characteristic of endocyclic N binding. The hard metal salts, Ba(NO 3) 2 and Pr(NO 3) 3 interacted weakly, if at all, with 2-diethylamino-7-methyl-9-propyl-6-thiopurinium betain whereas the nitrate salts of Zn, Cd and Pb gave pronounced upfield shifts of C6. This result is consistent with coordination at the exocyclic S. The compound, 2-dimethylamino-9-methylhypoxanthine, was prepared starting from 5-amino-4,6-dihydroxy-2-dimethylaminopyrimidine. This 5-aminopyrimidine derivative and methyl isothiocyanate were converted to N-(4,6-dihydroxy-2-dimethylamino-5-pyrimidinyl)-N′-methylthiourea which was then converted to 2-dimethylamino-6-hydroxy-9-methyl-8-purinethiol with hot hydrochloric acid. Raney nickel desulfurization in a basic solution gave 2-dimethylamino-9-methylhypoxanthine. The related compounds, 2-ethylamino-9-propyl- and 2-diethylamino-9-propylhypoxanthine, were prepared from 4,6-diamino-2-methylmercapto-5-nitrosopyrimidine. Treatment of this pyrimidine with dimethyl-, ethyl- and diethyl-amine led to the initial intermediate 2-alkyl-amino-4,6-diamino-5-nitrosopyrimidines. Treatment of these pyrimidines with sodium hydrosulfite, formic acid and formamide in one flask gave the mixture of corresponding 2-alkyl-aminoadenines and 2-alkylamino-6-formamido-purines. The latter compounds were successfully converted to the desired 2-alkylaminoadenines by alkali treatment. Alkylation with alkyl halides at the 9-positions of these adenine derivatives and subsequent deamination with nitrous acid gave 2-dimethylamino-9-methyl-, 2-ethylamino-9-propyl- and 2-ethylamino-9-propylhypoxanthines. These hypoxanthines were further methylated at their 7-position to give the corresponding hypoxanthinium betains. 2-Diethylamino-7-methyl-9-propyl-6-thiopurinium betain was prepared by the methylation at the 7-position of 2-diethylamino-9-propylhypoxanthine followed by 6-chlorination and, then, by treatment with thiourea.

The synthesis and characterization of 3,3-disubstituted pent-4-enals and their 2,2-(trimethylenedithio)pent-4-enal precursors, including the X-ray crystal structure of (R)-3-ethyl-3-phenyl-2,2-(trimethylenedithio)pent-4-enal

A variety of 3,3-disubstituted pent-4-enals (5a, R = Me, R′ = Et; 5b, R = Me, R′ = Ph; 5c, R = Et, R′ = Ph) has been prepared by the Raney nickel desulfurization of the corresponding 3,3-disubstituted 2,2-(trimethylenedithio)pent-4-enal precursors 4a–4c. The precursor compounds were prepared by the alkylation of 2-formyl-1,3-dithiane with the appropriate 3,3-disubstituted allylic bromide. The new compounds have been characterized by elemental analysis, infrared and nmr spectroscopy, and mass spectrometry. The crystal and molecular structure of (R)-4c has also been determined by X-ray crystallography. At temperatures of ca. 130 °C, compounds 4a–4c undergo intramolecular rearrangement to form the tri-substituted alkenes 6a–6c, which have also been characterized by the present study.

Total synthesis of the unique mycotoxin .alpha.-cyclopiazonic acid (.alpha.CA): an unusual dimethylzinc mediated replacement of a phenylthio substituent by a methyl group and a contrathermodynamic Raney nickel desulfurization reaction

Total synthesis of the unique mycotoxin .alpha.-cyclopiazonic acid (.alpha.CA): an unusual dimethylzinc mediated replacement of a phenylthio substituent by a methyl group and a contrathermodynamic Raney nickel desulfurization reaction

The inadequacy of the Raney nickel desulfuration method for the structural elucidation of an epoxide-glutathione S-conjugate: desulfuration of phenyloxiran-glutathione S-conjugates to phenyloxiran.

Both of purely separated regioisomers of phenyloxiran-glutathione S-conjugates, conjugate 1 (S-(1-phenyl-2-hydroxyethyl)glutathione) and conjugate 2 (S-(2-phenyl-2-hydroxyethyl)glutathione), afforded phenyloxiran as a common intermediate to the major desulfuration products, phenethyl alcohol and ethylbenzene, and to the minor ones, methylphenylcarbinol and toluene, on the mild treatment with Raney nickel in boiling ethanol. Phenyloxiran formed was hydrogenated to stable phenethyl alcohol and unstable methylphenylcarbinol under the catalytic conditions used, the latter of which was readily deoxygenated to ethylbenzene. The present study indicated that the Raney nickel method, despite of its being recognized to be well established, could not be applicable to the structural assignment of epoxide-glutathione or epoxide-mercapturic acid conjugates.

2,5-anhydro-1-deoxy- d-lyxitol, 2,5-anhydro-1-deoxy- d-mannitol, and 2,5-anhydro-1-deoxy- d-talitol. Synthesis and enzymic studies

2,5-Anhydro-1-deoxy- d-mannitol ( 4), 2,5-anhydro-1-deoxy- d-talitol ( 8), and 2,5-anhydro-1-deoxy- d-lyxitol ( 12) were prepared by Raney-nickel desulfurization of 2,5-anhydro- d-mannose dihexyl dithioacetal ( 3), 2,5-anhydro- d-talose dihexyl dithioacetal ( 7), and 2,5-anhydro- d-lyxose diethyl dithioacetal ( 11), respectively, in 64% yield based on starting thioacetal. Compounds 3 and 7 were prepared in 42% yield, by the acid-catalyzed condensation of 2,5-anhydro- d-mannose and 2,5-anhydro- d-talose, respectively, with hexanethiol. Compound 11 was prepared in 66% yield, by treatment of d-lyxose diethyl dithioacetal with p-toluenesulfonyl chloride-pyridine. Compounds 4, 8, and 12 were examined as substrates and inhibitors for yeast hexokinase and bovine-liver fructokinase. Hexokinase and fructokinase phosphorylated 4 with K m values of 25 and 1.94m m, and V max ( 4)/ V max ( d-fructose) 0.007 and 0.13, respectively. Fructokinase was competitively inhibited by 8 and 12, with K i values of 17 and 99m m, respectively.

Secretion and secretory tissues of the anal sac of the mink,Mustela vison

The sulfur-rich anal sac secretion of the mink,Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apocrine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putrescine (1,4-diaminobutane). The identity of the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3-dimethyl-1, 2-dithiacyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiacyclobutanes, a number of disulfides and 3-methyl-but-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed.

A novel method for the methylation of heterocyclic amino groups. Conversion of guanosine into its 2- N-methyl- and 2- N,2- N-dimethyl derivatives

The heterocyclic amino-compounds 11a, 13a, 13b, and 17 reacted with formaldehyde and p-thiocresol ( 14) in alcoholic solution to give the corresponding N-methylphenylthiomethyl derivatives ( 16, 15a, 15b, and 18a, respectively) in satisfactory to good yields. The reactions were catalyzed by acetic acid. 2- N-Methylguanosine ( 6a) was obtained in good yield by treatment of 15b with sodium borohydride followed by acidic hydrolysis, or alternatively by Raney nickel desulfurization of 15a followed by ammonolysis of the product. Sodium borohydride reduction of 18a gave 21 in good yield. 2- N,2- N-Dimethylguanosine ( 6b) was obtained from 19a in three steps.

Pyrrole chemistry. XVIII. The thio-Claisen rearrangement

The thio-Claisen rearrangement has been carried out on 2-allylthiopyrrole, l-methyl-2-allylthiopyrrole, and 2,5-diallylthiopyrrole. The products were trapped by acetylation of the β-allyl-α-thiols. Raney nickel desulfurization of these products gave the corresponding β-propylpyrroles but attempts to functionalize the β-allyl group failed. l-Methyl-3-propylpyrrole and 3,4-dipropylpyrrole were also synthesized by other routes for comparison.

Reduction studies on benzaza[3.3.3]propellanc derivatives

AbstractSodium borohydride reduction of 3‐methyl‐2,3‐dioxo‐7,8‐benzo‐3‐aza[3.3.3]propellan‐6‐one (1b) gave 2,4‐dioxo‐3‐methyl‐7,8‐benzo‐3‐aza[3.3.3]propellan‐6‐ol, while lithium aluminum hydride reduction gave 3‐methyl‐7,8‐benzo‐3‐aza[3.3.3]propellan‐6‐ol, which on oxidation, gave the corresponding ketone. This ketone formed the corresponding thioketal upon reaction with 1,2‐ethanedithiol. Raney nickel desulfurization of the thioketal provided 3‐methyl‐6,7‐benzo‐3‐aza[3.3.3]propellane. The same compound was also obtained in poor yield by forming the thioketal of Ib followed by lithium aluminum hydride reduction and Raney nickel desulfurization of the product. Desulfurization of the thioketal of Ib gave 2,4‐dioxo‐6,7‐Benzo‐3‐aza[3.3.3]propellane.

Studies of nucleosides and nucleotides. LXVIII. Purine cyclonucleosides. 29. Synthesis and properties of O-cyclonucleosides derived from hyposanthine, mercaptopurine, methylmercaptopurine and purine.

The O-cyclonucleosides of hypoxanthine, 6-mercaptopurine, 6-methylmercaptopurine, and purine were synthesized. Cyclonucleosides of hypoxanthine, and 6-mercaptopurine were synthesized i) by the derivatization of corresponding adenine cyclonucleosides and ii) by the cyclization of appropriate 2'-or 3'-TPS-derivatives. Cyclonucleosides of 6-methylmercaptopurine and purine were synthesized from the corresponding 6-mercaptopurine cyclonucleosides by methylation and Raney Nickel desulfurization. Ultraviolet spectrum (UV), nuclear magnetic resonance (NMR), circular dichroism (CD) and Mass spectra of these cyclonucleosides were measured. It was found in the CD spectrum that the purine 8, 2'-cyclonucleoside had a larger magnitude of Cotton effect than its 8, 3'-counterpart, in contrast to the order found in other cyclonucleosides.