Syntheses and structures of vinyl and aryl derivatives of carbonyl halide iron complexes

cis,trans-Fe(CO)₂(PMe₃)₂(p-Y-C₆H₄)X [X=Br, Y=H (4a), MeO (4b), Cl (4c), F (4d), Me (4e); X=I, Y=H (5); X=Cl, Y=H (6)] and cis,trans-Fe(CO)₂(PMe₃)₂(σ-CHCH₂)X [X=Br (7); X=I (8); X=Cl (9)] are prepared by reacting dihalide complexes cis,trans,cis- Fe(CO)₂(PMe₃)₂X₂ [X=Br (1), X=I (2), X=Cl (3)] with Grignard reagents p-Y-C₆H₄-MgBr (Y=H, OMe, Cl, F, Me) or CH₂CH-MgBr and with lithium reagents PhLi, CH₂CH-Li. With both reagents, the reaction proceeds following two parallel pathways: one is the metallation reaction which yields alkyl derivatives, the other affords 17 electron complexes [Fe(CO)₂(PMe₃)₂X] via monoelectron reductive elimination. The influence of the halides and organometallic reagents on the yield of the metallation reaction is discussed. The solution structure of the complexes is assigned on the basis of IR and ¹H, ¹³C, ¹⁹F, ³¹P NMR spectra. The solid state structure of complexes 4a, 5 and 6 is determined by single crystal X-ray diffractometric methods.     

Genetic control of methyl halide production in Arabidopsis

Methyl chloride (CH(3)Cl) and methyl bromide (CH(3)Br) are the primary carriers of natural chlorine and bromine, respectively, to the stratosphere, where they catalyze the destruction of ozone, whereas methyl iodide (CH(3)I) influences aerosol formation and ozone loss in the boundary layer. CH(3)Br is also an agricultural pesticide whose use is regulated by international agreement. Despite the economic and environmental importance of these methyl halides, their natural sources and biological production mechanisms are poorly understood. Besides CH(3)Br fumigation, important sources include oceans, biomass burning, tropical plants, salt marshes, and certain crops and fungi. Here, we demonstrate that the model plant Arabidopsis thaliana produces and emits methyl halides and that the enzyme primarily responsible for the production is encoded by the HARMLESS TO OZONE LAYER (HOL) gene. The encoded protein belongs to a group of methyltransferases capable of catalyzing the S-adenosyl-L-methionine (SAM)-dependent methylation of chloride (Cl(-)), bromide (Br(-)), and iodide (I(-)) to produce methyl halides. In mutant plants with the HOL gene disrupted, methyl halide production is largely eliminated. A phylogenetic analysis with the HOL gene suggests that the ability to produce methyl halides is widespread among vascular plants. This approach provides a genetic basis for understanding and predicting patterns of methyl halide production by plants.     

13C-NMR of methyl,methylene and carbonyl carbon atoms of methyl alkenoates and alkynoates

The carbon magnetic resonance spectra of 102 fatty acid methyl esters with cis and trans double bonds and triple bonds at various positions and in many different combinations have been investigated. A comprehensive set of chemical shift parameters has been developed for the various substituents. With the aid of these parameters, the chemical shifts of all methyl, methylene carbonyl carbon atoms can be predicted with an accuracy of ±0.1 ppm or better.     

A review of bacterial methyl halide degradation: biochemistry,genetics and molecular ecology

Methyl halide-degrading bacteria are a diverse group of organisms that are found in both terrestrial and marine environments. They potentially play an important role in mitigating ozone depletion resulting from methyl chloride and methyl bromide emissions. The first step in the pathway(s) of methyl halide degradation involves a methyltransferase and, recently, the presence of this pathway has been studied in a number of bacteria. This paper reviews the biochemistry and genetics of methyl halide utilization in the aerobic bacteria Methylobacterium chloromethanicum CM4T, Hyphomicrobium chloromethanicum CM2T, Aminobacter strain IMB-1 and Aminobacter strain CC495. These bacteria are able to use methyl halides as a sole source of carbon and energy, are all members of the alpha-Proteobacteria and were isolated from a variety of polluted and pristine terrestrial environments. An understanding of the genetics of these bacteria identified a unique gene (cmuA) involved in the degradation of methyl halides, which codes for a protein (CmuA) with unique methyltransferase and corrinoid functions. This unique functional gene, cmuA, is being used to develop molecular ecology techniques to examine the diversity and distribution of methyl halide-utilizing bacteria in the environment and hopefully to understand their role in methyl halide degradation in different environments. These techniques will also enable the detection of potentially novel methyl halide-degrading bacteria.     

Theoretical studies on identity SN2 reactions of lithium halide and methyl halide: A microhydration model

Reactions of lithium halide (LiX, X = F, Cl, Br and I) and methyl halide (CH₃X, X = F, Cl, Br and I) have been investigated at the B3LYP/6-31G(d) level of theory using the microhydration model. Beginning with hydrated lithium ion, four or two water molecules have been conveniently introduced to these aqueous-phase halogen-exchange S_N2 reactions. These water molecules coordinated with the center metal lithium ion, and also interacted with entering and leaving halogen anion via hydrogen bond in complexes and transition state, which to some extent compensated hydration of halogen anion. At 298 K the reaction profiles all involve central barriers ΔE _cent which are found to decrease in the order F > Cl > Br > I. The same trend is also found for the overall barriers (ΔE _ovr ) of the title reaction. In the S_N2 reaction of sodium iodide and methyl iodide, the activation energy agrees well with the aqueous conductometric investigation.     

Synthesis and evaluation of methyl ether derivatives of the vancomycin, teicoplanin, and ristocetin aglycon methyl esters

A series of methyl ether derivatives of the vancomycin, teicoplanin, and ristocetin aglycon methyl esters was synthesized and their antimicrobial activity was established. These derivatives exhibit increased activity against VanB resistant strains of bacteria equipotent with that observed with sensitive bacteria.     

Effects of carbonyl sulfide, methyl iodide, and sulfuryl fluoride on fruit phytotoxicity and insect mortality

Three potential chemical fumigants: carbonyl sulfide (COS), methyl iodide (MI) and sulfuryl fluoride (SF) were tested at selected dosages on lemons against California red scale (Aonidiella aurantii) and MI and COS were tested on nectarines against codling moth (Cydia pomonella). In nectarines, COS was tested at 0, 20, 40, 60 and 80 mg litre^?1, MI at 0, 10, 15, 20 and 25 mg litre^?1. Both fumigants intensified nectarine peel color, delayed fruit softening, but did not alter overall fruit quality. COS at 80 mg litre^?1 resulted in 87% codling moth mortality, but the fumigant dosage was insufficient to reach the desired probits 9 level (99.9968%). MI gave 100% codling moth mortality at 25 mg litre^?1. Lemons were treated with MI at 0,10,20,40,60 mg litre^?1, SF at 0,10,20,40, 80 mg litre^?1 and COS at 0,20,40, 60 and 80 mg litre^?1. MI gave 100% red scale mortality at ≥40 mg litre^?1 but caused significant fruit injury. Conditioning lemons at 15°C for 3 days before MI fumigation lessened lemon phytotoxicity. Forced aeration at 3.5 standard litres per minute of lemons for 24 h following MI fumigation at 20 mg litre^?1 significantly reduced phytotoxicity compared to 2 h postfumigation aeration after MI treatment. SF at ≥40 mg litre^?1 gave 100% red scale mortality but resulted in commodity phytotoxicity. Lemons treated with the highest selected dose of 80 mg litre^?1 COS gave only 87% kill of red scale, but failed to reach the desired probit 9 level.     

Sodium halide complexes of ribose derivatives and their unusual crystal structures

Crystalline complexes of d-ribose, d-ribono-1,4-lactone and methyl β-d-ribopyranoside with sodium halides were synthesized and some of their crystal structures determined. Crystal structures of two lactone complexes and a methyl β-d-ribopyranoside reveal the mode of the salt binding and the intricate interplay of cation coordination and hydrogen bonding in these complexes. When complexed with NaBr, the ribopyranoside is in the ¹C₄ shape whereas ribose with no salt present has the ⁴C₁ shape. It is also demonstrated that such complexes can be easily prepared in solid state reaction using a ball mill.     

New class of quaternary ammonium salts, derivatives of methyl D-glucopyranosides

Reactions of two aromatic and two aliphatic amines with methyl 6-O-p-toluenesulfonyl-alpha-D-glucopyranoside or methyl 6-O-p-toluenesulfonyl-beta-D-glucopyranoside were performed on a micro-scale. The synthesis and preparative isolation methods have been developed for quaternary N-(methyl 2,3,4-tri-O-acetyl-6-deoxy-alpha- and -beta-D-glucopyranoside-6-yl)ammonium salts derived from three amines: trimethylamine, 2-methylpyridine, and pyridine. The reaction products were examined with 1H, 13C NMR spectroscopy. N-(Methyl 2,3,4-tri-O-acetyl-6-deoxy-beta-d-glucopyranoside-6-yl)trimethylammonium tosylate was additionally analyzed with X-ray crystallography.     

Ammonia ruthenium complexes for the access to new hydrido, carbonyl and isocyanide ruthenium-alkynyl derivatives

The potential in preparative chemistry of the precursors trans-[Ru(NH₃)(CC---R¹)(Ph₂PCH₂CH₂PPh₂)₂]PF₆ (3) has been studied. They offer a convenient access, by NH₃ displacement, to new functional alkynyl-ruthenium derivatives. Complexes 3 react with alkynes HCC---R² to give unsymmetrical trans-Ru(---CC---R¹)(---CC---R²)(dppe)₂ compounds 4a-c, and with sodium methoxide in methanol they open the route to a variety of mixed hydride complexes 5a-c, trans-Ru(H)(---CC---R¹)(dppe)₂. In contrast, with carbon monoxide or isocyanides CN---R³ (R³:CH₂Ph, C₆H₁₁, Me₃C) they allow the preparation of cationic derivatives trans-(Ru(CO)(---CC---R¹)(dppe)₂]PF₆ (6a-c) or trans-[Ru(CNR³)(---CC---R¹)(dppe)₂]PF₆ (7a-d).     

Analysis of genes involved in methyl halide degradation in Aminobacter lissarensis CC495

Aminobacter lissarensis CC495 is an aerobic facultative methylotroph capable of growth on glucose, glycerol, pyruvate and methylamine as well as the methyl halides methyl chloride and methyl bromide. Previously, cells grown on methyl chloride have been shown to express two polypeptides with apparent molecular masses of 67 and 29 kDa. The 67 kDa protein was purified and identified as a halomethane:bisulfide/halide ion methyltransferase. This study describes a single gene cluster in A. lissarensis CC495 containing the methyl halide utilisation genes cmuB, cmuA, cmuC, orf 188, paaE and hutI. The genes correspond to the same order and have a high similarity to a gene cluster found in Aminobacter ciceronei IMB-1 and Hyphomicrobium chloromethanicum strain CM2 indicating that genes encoding methyl halide degradation are highly conserved in these strains.     

Reductive N,N-dimethylation of amino acid and peptide derivatives using methanol as the carbonyl source

Formaldehyde is readily formed from methanol in the presence of palladium-on-charcoal and air. The use of this methanolic formaldehyde solution for the reductive methylation of amino groups in amino acid and peptide derivatives by catalytic hydrogenation has been studied and found to be superior to the use of aqueous formaldehyde because no contaminating paraformaldehyde is present. Some data on N-isopropylation are given.     

Syntheses of di-hydrocarbyl derivatives of carbonyl phosphine complexes of iron

Complexes cis,trans-Fe(CO)₂(PMe₃)₂RR′ (R = CH₃, R′ = Ph (2); R = CH₃, R′ = CHCH₂ (3); R = CHCH₂, R′ = Ph (4); R = R′ = CHCH₂ (5); R = R′ = CH₃ (6)) were prepared by reaction of cis,trans-Fe(CO)₂(PMe₃)₂RCl (1) with organolithium reagents LiR′. All complexes were characterized in solution by IR and ¹H, ³¹P and, in a few cases, ¹³C NMR mono- and bi-dimensional spectroscopies. Complexes 5 and 6 were structurally characterized by X-ray diffractometric methods. In solution complexes 2, 3 and 4 undergo slowly coupling of the σ-hydrocarbyl substituents leading to Fe(CO)₃(PMe₃)₂ and other decomposition products. Complex 6 was very stable in solution in the absence of nucleophiles and in the solid state. Complex 5 transformed through intramolecular coupling of the vinyl groups into Fe(CO)(PMe₃)₂(η⁴-butadiene) (7), which was characterized in solution by IR and NMR spectroscopies.     

Environmental and biological controls on methyl halide emissions from southern California coastal salt marshes

Methyl bromide (CH₃Br) and methyl chloride(CH₃Cl) emission rates from southernCalifornia coastal salt marshes show largespatial and temporal variabilities that arestrongly linked to biological and environmentalfactors. Here we discuss biogeochemical linesof evidence pointing to vegetation as theprimary source of CH₃Br and CH₃Clemissions from salt marshes. Sediments andmacroalgae do not appear to be major producersof these compounds, based on observations thatthe highest fluxes are not inhibited by soilinundation; their emissions are not correlatedwith those of certain gases produced in soils;and emissions from mudflat- andmacroalgae-dominated sites are relativelysmall. In contrast, the seasonal and spatialvariabilities of methyl halide fluxes in thesesalt marshes are consistent with the productionof these compounds by vascular plants, althoughthe possibility of production by microflora orfungi associated with the salt marsh vegetationis not ruled out. Flux chamber measurements ofemission rates are largely correlated to theoverall plant biomass enclosed in the chamber,but appear also to be highly dependent on thepredominant plant species. Emission ratesfollow a diurnal trend similar to the trends ofambient air temperature and photosyntheticallyactive radiation, but not surface soiltemperature. Diurnal variabilities in thecarbon isotope compositions of CH₃Cl andCH₃Br and their relative ratios ofemissions are consistent with simultaneouslycompeting mechanisms of uptake andproduction.     

Evaluation of genotoxity and mutagenicity of DL-p-chlorophenylalanine, its methyl ester and some N-acyl derivatives

DL-p-chlorophenylalanine (PCPA) and its derivatives were evaluated for genotoxic effects using Escherichia coli and Bacillus subtilis strains lacking various DNA-repair mechanisms in spottest and in suspension test. The mutagenic activity of studied compounds was determined by the Ames test. Reverse mutation test was performed with Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 without S9 mix. 0.02 M nitrosomethylurea (NMU) standard mutagen was used as a positive control. The results showed that the parent nonessential amino acid PCPA had no detectable genotoxic and mutagenic activities in bacteria. The methyl ester of this amino acid and its N-phenylacetyl derivative possessed weak genotoxicity. Meanwhile N-sec-butyloxycarbonyl, N-benzyloxycarbonyl, N-(p-nitrophenylacetyl) and N-(p-nitrophenoxyacetyl) derivatives of DL-p-chlorophenylalanine exhibited appreciable genotoxicity. Among the seven tested compounds only N-benzyloxycarbonyl and N-(p-nitrophenoxyacetyl) derivatives of DL-p-chlorophenylalanine have been found to be mutagenic. Only parent PCPA possessed antimutagenic properties in respect of nitrosomethylurea. The structural modification, which strongly affects genotoxicity and mutagenicity perhaps may be due to steric hydrance of the substituents, causing interference with enzyme and DNA interactions.     

Ester hydroxy derivatives of methyl oleate: tribological, oxidation and low temperature properties

Five branched oleochemicals were prepared from commercially available methyl oleate and common organic acids; and their lubricant properties were determined. These branched oleochemicals are characterized as 9(10)-hydroxy-10(9)-ester derivatives of methyl oleate. These derivatives show improved low temperature properties, over olefinic oleochemicals, as determined by pour point and cloud point measurements. The derivatization also increased thermo-oxidative stability, measured using both pressurized differential scanning calorimetry (PDSC) and thin film micro oxidation (TFMO) methods. Branched oleochemicals were used as additives both in soybean oil and in polyalphaolefin. Their lubrication enhancement was evaluated by both four-ball and ball-on-disk wear determinations. These derivatives have good anti-wear and friction-reducing properties at relatively low concentrations, under all test loads. Their surface tensions were also determined and a trend was observed. The materials with larger side chain branches had lower surface tension than those containing smaller side chain branches. An exception to this trend was found when studying the compound with the carbonyl containing levulinic acid side chain, which had the highest surface tension of the branched oleochemicals studied. Overall, the data indicate that some of these derivatives have significant potential as a lubricating oil or fuel additives.     

Mass spectrometry of uronic acid derivatives. Part V. Fragmentation of methyl derivatives of methyl 4-deoxy-beta-L-threo-hex-4-ehopyranosiduronic-acid.

The basic fragmentation mechanism of methyl(methyl 4-deoxy-2,3-di-O-methyl-β-l-threo-hex-4-enopyranosid)uronate has been deduced by deuteromethylation analysis, metastable transition measurements, and by interpreting the spectra of weakly excited foregoing molecules. The differences in fragmentation of partially methylated derivatives of methyl 4-deoxy-β-l-threo-hex-4-enopyranosiduronic acid compared to that of the fully methylated substance are discussed in detail and the criteria are proposed for identification of the compounds concerned by mass spectrometry.     

A theoretical study on the coordination behavior of some phosphoryl,carbonyl and sulfoxide derivatives in lanthanide complexation

The selectivity of phosphoryl P(O)R₃, sulfoxide S(O)R₂, and carbonyl C(O)R₂ (R?=?NH₂, CH₃, OH, and F) derivatives with lanthanide cations (La³⁺, Eu³⁺, Lu³⁺) was studied by density functional theory calculations. Theoretical approaches were also used to investigate energy and the nature of metal–ligand interaction in the model complexes. Atoms in molecules and natural bond orbital (NBO) analyses were accomplished to understand the electronic structure of ligands, L, and the related complexes, L–Ln³⁺. NBO analysis demonstrated that the negative charge on phosphoryl, carbonyl, and sulfoxide oxygen (O_P, O_C, and O_S) has maximum and minimum values when the connected –R groups are –NH₂ and –F. The metal–ligand distance declines as, –F?>?–OH?>?–CH₃?>?–NH₂. Charge density at the bond critical point and on the lanthanide cation in the L–Ln³⁺ complexes varies in the order –F?<?–OH?<?–CH₃?<?–NH₂, due to greater ligand to metal charge transfer, which is well explained by energy decomposition analysis. It was also illustrated that E⁽²⁾ values of Lp(N)?→?σ*(Y–N) vary in the order P=O ? S=O ? C=O and the related values of Lp(N)?→?σ*(Y=O) change as C=O ? S=O ? P=O in (NH₂)_nYO ligands (Y?=?P, C, and S). Trends in the L–Ln³⁺ CP–corrected bond energies are in good accordance with the optimized O_Y?Ln distances. It seems that, comparing the three types of ligands studied, NH₂–substituted are the better coordination ligands.

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Graphical Abstract Density functional theory (B3LYP) calculations were used to compare structural, electronic and energy aspects of lanthanide (La, Eu, Lu) complexes of phosphine derivatives with those of carbonyls and sulfoxides in which the R– groups connected to the P=O, C=O and S=O are –NH₂, –CH₃, –OH and –F.