Phosphitylation and quantitative P NMR analysis of partially substituted biodiesel glycerols

The main step during biodiesel production is the catalytic transesterification of triglycerides. Glycerol and fatty acids are by-products of the biodiesel production and considered as contaminants in the final product. By selectively measuring the amount of fatty acids and glycerol with different substitution levels, the yield of this step and the quality of the final biodiesel can be determined.This study examines the application of phosphitylation of glycerol hydroxyl groups with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane followed by ³¹P NMR analysis to provide a rapid quantitative analytical technique for the determination of substitution patterns on partially esterified glycerols, alcohols and the detection of fatty acids. ³¹P NMR chemical shift data was established with a series mono and di-substituted esters of glycerol, fatty acids and alcohols, then utilized to characterize commercial glycerol and biodiesel samples.     

Quinoxalines. IX. Reaction of 2-(Halogenomethyl)-quinoxalines and -quinoline with hydroxybenzoic acids and their esters

In the presence of a base the title compounds react to products with ether structure ( 4, 6 ), or with ester structure ( 3 ), or to structure 5 containing both functionalities in dependence on the mole ratio of the starting substances, on reaction conditions and on the substituent patterns in the hydroxybenzoic acid component. Under the influence of alkali hydroxide the m- and p-substituted compounds ( 6e–g ) are saponified to the alkali salts of the carboxylic acid ( 4b, c ). The o-substituted compounds ( 6a–d ), however, are cyclized to the benzo[b]furanylquinoxalines ( 8 ). 8a, d are also obtained by thermal water elimination of the carboxylic acids 4a, d . The red-coloured benzofuranols 8 react with acetic anhydride and benzoyl-chloride/pyridine, resp., to the weakly yellow esters 9 . The stucture of the products 8 and 9 is studied by UVVIS derivative spectroscopy, by theoretical calculation of the dihedral angles and by ¹H and ¹³C NMR spectroscopy. The ¹H and ¹³C chemical shifts are completely assigned. The quinoxalines 8a–c and the quinoline 8d only exist in the hydroxy form.     

Preparation,IR, UV,NMR, and Mass Spectral Fragmentations of New Substituted Phenoxaphosphinic Acids

The synthesis and IR, UV, NMR; and mass spectral fragmentations of substituted phenoxaphosphinic acids I – XIV are reported. A diazo method gave I, and the Friedel-Crafts method II – XIV. Infrared assignments: POH, broad bands, 2600, 2250, and 1650; C-P, 1490 - 1440; C-O, 1280 - 1260; P=0, 1190 - 1140; and P-O, 978 - 974 cm^?1. Characteristic bands also occur at 1330 - 1320 and 1230 - 1210 cm^?1. The UV spectra possess maxima at 210 - 220 mμ (log ∈ 4.50 - 4.60), 240 - 250 (4.20 - 4.30), and 298 – 304 (3.65 – 3.75). The NMR spectra give τ 7.56 ppm for a 2-methyl substituent, 7.48 for a 4-methyl and a quartet at 7.26 and a triplet at 8.71 (J = 7.7 Hz) for a 2-ethyl. The chemical shifts were virtually unaffected by alkyl or halogen substituents on the other aromatic ring but were shifted upfield by ortho or meta methyl substituents on the same ring. Singlets at τ 7.44 and 7.60 ppm in the spectrum of VIII gave calculated base values of about 7.28 and 7.44 for a 1-methyl and 3-methyl, respectively. The mass spectra are greatly influenced by the substituents. All showed loss of PO₂H from the molecular ion or in the case of ethyl compounds after CH₃^· expulsion. CHO or CCIO was then eliminated. The molecular ions of methyl compounds eliminated H₂O.     

Simple,Mild, and Practical Esterification,Thioesterification, and Amide Formation Utilizing p‐Toluenesulfonyl Chloride and N‐Methylimidazole

We have developed an efficient method for the esterification or thioesterification of equimolar amounts of carboxylic acids and alcohols or thiols using a novel reagent, p‐toluenesulfonyl chloride (TsCl) together with N‐methylimidazole. The present method is simple, mild, and reactive, uses readily available and economical reagents. The choice of amine is critical for the present method. The amine, N‐methylimidazole, has two roles: (i) as an HCl scavenger for the initial smooth generation of mixed anhydrides between carboxylic acids and TsCl and (ii) successive formation of highly reactive ammonium intermediates from mixed anhydrides. This method could be applied to various types of carboxylic acids, alcohols, and thiols: a) several functionalities were tolerated; b) two N‐Cbz amino acids were smoothly esterified without racemization; and c) the labile 1β‐methylcarbapenem key intermediate and a pyrethroid insecticide, prallethrin, were successfully prepared. The related amide formation between carboxylic acids and primary or secondary amines was also performed. The proposed reaction mechanism involves a novel method for producing the reactive acylammonium intermediates. The production of these intermediates was rationally supported by a careful ¹H NMR monitoring study.     

TLC and <Superscript>31</Superscript>P-NMR Analysis of Low Polarity Phospholipids

High-performance TLC and ³¹P-NMR were assessed as methods of observing the presence of numerous low polarity phospholipids: bis-phosphatidic acid (BPA), semi-lyso bis-phosphatidic acid (SLBPA), N-acyl phosphatidylethanolamine (NAPE), N-(1,1-dimethyl-3-oxo-butyl)-phosphatidylethanolamine (diacetone adduct of PE, DOBPE), N-acetyl PE, phosphatidylmethanol (PM), phosphatidylethanol (PEt), phosphatidyl-n-propanol (PP), phosphatidyl-n-butanol (PB). Both techniques are non-discriminative and do not require the prior isolation of individual lipids. It appears that 2D TLC is superior to ³¹P NMR in the analysis of low polarity phospholipids. All phosphatidylalcohols were well separated by 2D TLC. However, some compounds which can present difficulty in separation by 2D-TLC (e.g., SLBPA and NAPE; or DOBPE and N-acetyl PE) were easily distinguished using ³¹P NMR so the methods are complimentary. A disadvantage of 2D TLC is that Rf values can vary with different brands and batches of TLC plates. The chemical shifts of ³¹P NMR were less variable, and so a library of standards may not be necessary for peak identification. Another advantage of ³¹P NMR is the ease of quantification of phospholipids. The applicability of the methods was tested on natural extracts of fish brain and cabbage stem.     

NMR study of the lipid profile of mullet raw roe and bottarga

Samples of mullet (Mugil cephalus) roes from two different fishing areas were studied by means of ¹H, ¹³C and ³¹P NMR and GC techniques. The lipid fraction of unprocessed roes and that of the corresponding salted and dried commercial products “bottarga” were analyzed and the data compared. Roes of mullets from different origin showed different composition regarding mainly triacylglycerols, monounsaturated and n‐3 polyunsaturated fatty acids. The NMR spectra of processed roes, compared to those of the corresponding raw materials, showed a release of free fatty acids and the formation of other minor molecular components, such as free fatty alcohols, lysophospholipids, and diacylglycerols, thus indicating that hydrolytic processes were the main consequence of manufacturing. An increase of cholesterol ester concentration after processing was also detected. Through the analysis of the ³¹P NMR spectra, it was possible to follow the fate of the phospholipids and the formation of lysophospholipids induced by the salting and drying procedures.     

Synthesis and Characterization of Sulfur Containing Dextran- and β-Cyclodextrin Derivatives

Summary Sulfur containing dextran and β-cyclodextrin derivatives were synthesised as alternitive coating materials for gold surfaces. The esterification of the carbohydrates with thiophene carboxylic acids and α-lipoic acid was carried out in DMSO by in situ activation of the acids with N,N’-carbonyldiimidazole. The thiophene carboxylic acids vary in the position of the sulfur atom and the spacer between the thiophene and the carboxylic group. DS values ranging from 0.44 to 2.04 were accessible depending both on the carbohydrate and the acid used. Insoluble derivatives were obtained by the conversion of α-lipoic acid with the carbohydrates. The structure of the derivatives soluble in DMSO and DMF was examined by IR- and NMR spectroscopy. Furthermore, subsequent acylation reveals a useful tool for the determination of the degree of substitution of the thiophene derivatives additionally to elemental analysis.     

Determination of the Z 1H NMR chemical shift substituent parameters for the sulfinyl chloride and sulfinate ester functionalities

Using established and new ¹H NMR data for sulfinate esters and sulfinyl chlorides, the parameters required for predicting position-dependent alkene ¹H NMR chemical shifts of vinylic sulfinate esters and vinylic sulfinyl chlorides have been obtained. Standard deviations of the new Z parameters lie in the range 0.08 to 0.15?ppm. Sulfinyl chloride and cyclohexyl sulfinate derivatives of (E) and (Z)-2-cyanoethenesulfinic acids have been prepared for the first time.     

A study of benzylphenols as antioxidants

A series of benzylphenols has been evaluated as antioxidants for paraffin wax at 160 C. Introduction of the benzyl group to thepara- and/or ortho-positions to the hydroxyl group on the benzene ring was shown to improve antioxidative activities of phenols. Excellent activities have been observed with benzylpyrocatechols and benzyl-resorcinol. Antioxidant activities of benzylphenol compounds increased with the decrease of¹³C NMR chemical shifts (δ) of the ipsocarbon of the OH substituent.     

New unsaturated derivatives of Xanthan gum: Synthesis and characterization

Unsaturated Xanthan derivatives, which can be used for the development of biodegradable three-dimensional networks having hydrogel properties, were prepared by esterification under various conditions. Xanthan gum derivatives with different degrees of substitution were obtained by reaction with an unsaturated organic acid (acrylic acid) or with acid reactive derivatives (acryloyl chloride, maleic anhydride). The presence of acrylate and maleate groups in the modified structure of Xanthan gum was detected by ATR-FTIR, ¹H liquid NMR and ¹H HRMAS NMR spectroscopies. The degree of substitution as determined by ¹H NMR could be controlled by varying the chemical nature of functionalisation agent, reaction time and temperature.The results proved that this polysaccharide can be modified by esterification with acids or unsaturated acid derivatives for further synthesis of hydrogels. Maleic anhydride presents a higher reactivity as compared to acrylic acid and acryloyl chloride.     

Preorganized macrocyclic receptors featuring endo-carboxylic acid Groups. Host synthesis and inclusion compounds with alcohol and amine guests

The synthesis and characterization of four new macrocyclic host compounds 1 – 4 having modified diphenylmethane units as bridging elements and two endo-orientated carboxylic acid groups attached to aromatic building blocks are described. The complexation properties of the macrocycles towards amines and alcohols are reported, showing that the ability to form convergent inclusion compounds depends on the type of the spacer element. For the dicarboxylic hosts 1 and 2 endo-complexation of guest molecules based on hydrogen bonding to the acid functions is proved using ¹H NMR investigation and X-ray crystal structure analysis.     

Surface active properties of a biosurfactant fromCorynebacterium lepus

A mixture of corynomycolic acids (R¹-CH(OH)-CH(R²)-COOH) isolated fromCorynebacterium lepus was shown to have excellent surfactant properties. It caused significant lowering of surface tension in aqueous solution and the interfacial tension between water and hexadecane at all values of pH between 2 and 10. A series of carboxylic acids and some hydroxy-carboxylic acids and alcohols were also studied as a comparison. None of these caused as large a lowering of the surface and interfacial tensions as the corynomycolic acids. The series of carboxylic acids studied showed that surfactant properties depend on the length of the alkyl chain and the pH of the solution in a manner consistent with the hydrophiliclipophilic balance of these compounds. Hydroxyl substituents caused considerable enhancement of the surfactant properties of long chain carboxylic acids if they were located close to the carboxyl function.     

Mammalian Exocrine Secretions. XVIII: Chemical Characterization of Interdigital Secretion of Red Hartebeest, Alcelaphus buselaphus caama

Gas chromatography, coupled gas chromatography-mass spectrometry (electron impact mode and chemical ionization with methane as reactant gas), gas chromatography-infrared spectroscopy, and derivatization techniques were used to identity 53 compounds in the interdigital secretion of the red hartebeest, Alcelaphus buselaphus caama. These compounds included alkanes, isoalkanes, alcohols, ketones, carboxylic acids, oxiranes, furanoid linalool oxides, and a large number of branched and unbranched saturated and unsaturated aldehydes. The secretion probably plays a role in demarcation of territories by dominant bulls.     

Substitution‐ and Elimination‐Free Phosphorylation of Functionalized Alcohols Catalyzed by Oxidomolybdenum Tetrachloride

Among 14 oxidometallic species examined for catalytic phosphorylation of the tested alcohols, oxidomolybdenum tetrachloride (MoOCl₄) was found to be the most efficient with a negligible background reaction mediated by triethylamine (Et₃N). The new catalytic protocol can be applied to the chemoselective phosphorylations of primary, secondary and tertiary alcohols as well as the substitution‐free phosphorylations of allylic, propargylic, and benzylic alcohols. Functionalized alcohols bearing acetonide, tetrahydropyranyl ether, tert‐butyldimethylsilyl ether, or ester group are also amenable to the new catalytic protocol. The most difficult scenarios involve substitution‐free phosphorylations of 1‐phenylethanol and 1‐(2‐naphthyl)ethanol which can be effected in 95 and 90% yields, respectively. ESI‐MS, IR, ¹H, and ³¹P NMR spectroscopic analyses of the reaction progress suggest the intermediacy of an alkoxyoxidomolybdenum trichloride‐triethylamine adduct such as [(RO)Mo(O)Cl₃‐Et₃N] to be responsible for the catalytic turnover.     

The calculation of sensitometric properties of 1,2,4-triazolo[1,5-a]pyrimidines

Quantitative structure–property relationships were proposed by using artificial neural networks and information received from ¹³C NMR spectra. The suitability of 1,2,4-triazolo[1,5-a]pyrimidines as stabilizers in photographic silver halide materials was determined from their chemical structures. For the numeric coding of the chemical structures of differently substituted 1,2,4-triazolo[1,5-a]pyrimidines 1 – 44 only information available from their ¹³C NMR spectra was used. Even an assignment of the ¹³C NMR chemical shift values to the carbons was not necessary. The best results were achieved by combination of the ¹³C NMR chemical shifts of carbons of the basic heterocycle and the relative fog D_rel using a feed-forward two-layer neural network. For some compounds with a good stabilizing effect the calculated results strongly differ from experimental values giving indication of a mechanism which is not covered by the ¹³C NMR chemical shifts.     

Mammalian exocrine secretions: X. constituents of preorbital secretion of grysbok,Raphicerus melanotis

Using electron impact and chemical ionization mass spectrometry with methane and nitric oxide as reactant gases in conjunction with mass spectral analysis of the dimethyl disulfide derivatives of unsaturated constituents, 51 compounds have been identified in addition to the compounds previously found in the preorbital secretion of the grysbokRaphicerus melanotis. The compounds identified are saturated, monounsaturated, and diunsaturated alcohols and formates, saturated and monounsaturated aldehydes, saturated carboxylic acids,- and-lactones, alkyl methyl sulfides, and-hydroxyalkyl acetates. All of these compounds have unbranched structures. The constituent previously incorrectly identified as (Z)-5-tetradecen-1-ol, was found to consist of the coeluting (Z)-7- and (Z)-8-tetradecenols.     

Chemical composition of the pyridine extracts of sapropel from the Irkutsk oblast

The sapropel of Lake Ochaul in the Irkutsk oblast was a test material. Pyridine extracts were separated from the sapropel after the sequential removal of hexane-soluble bituminous matter and humic acids and the enrichment of the residual sapropel. An analysis of the elemental composition, IR spectra, and fragment composition parameters obtained using quantitative ¹H and ¹³C NMR spectroscopy demonstrated that pyridine extracted a peculiar group of heteroatomic organic compounds from sapropel, which changed their composition in the course of a sapropel formation process. These compounds had alicyclic hydrocarbon fragments with double bonds with various degrees of substitution of aliphatic radicals, glycoside structures, and carboxylic acids.     

An unexpected ring carboxylation in the electrocarboxylation of aromatic ketones

The electrocarboxylation of various aromatic ketones, carried out in N-methyl-2-pyrrolidone (NMP) in a diaphragmless cell equipped with a carbon cathode and an aluminium sacrificial anode, yielded, among the products, the target hydroxy acids, the corresponding alcohols and pinacols and, quite surprisingly, detectable amounts of substituted benzoic acids and cycloexene carboxylic acids. These compounds arise from a never reported before electrocarboxylation on the aromatic ring, respectively, for substitution of an aromatic hydrogen and from an addition reaction. For example, the electrocarboxylation of acetophenone gave rise to the substituted benzoic acids in ortho, para and meta positions, while for 2,2-dimethylpropiophenone the substituted benzoic acid in meta position and the cyclohex-5en-1,3-dicarboxylic acid derivative were detected among the products.     

Metapleural Gland Secretion of the Leaf-cutter Ant Acromyrmex octospinosus: New Compounds and Their Functional Significance

Ants of the myrmicine tribe Attini live in symbiosis with a fungus that provides them with food. In return the ants maintain optimal growth conditions for the fungus, weed out competing microorganisms, and inhibit the growth conditions of these competitors by chemical means. We present a comprehensive analysis of metapleural gland secretions of Acromyrmex octospinosus, using a recently developed method for the analysis of polar compounds by gas chromatography and mass spectrometry. We show that the chemical identity and quantitative recovery of different compounds in the metapleural gland secretion depends upon the method used and the type of colony from which the samples are taken. In addition to the two compounds previously recorded in the metapleural gland secretion of Acromyrmex ants (indolacetic acid and myrmicacin), 20 new compounds were detected in the secretion of a random sample of workers from two laboratory colonies and two field colonies. These compounds span the whole range of carboxylic acids from acetic acid to the long-chain fatty acids but comprise also some alcohols, lactones, and keto acids. The possible function of this highly complex secretion mixture is discussed.     

Direct esterification of fatty acids with phenylalkanols by using dicyclohexylcarbodiimide

A mild one‐pot esterification method of fatty acids with alcohols at room temperature is described. The reaction of undec‐10‐enoic acid (I) with 1‐phenylethanol in the presence of N,N'‐di‐cyclohexylcarbodiimide and 4‐(N,N‐dimethylamino)pyridine gave 1'‐phenylethyl undec‐10‐enoate in quantitative yield. Similar reactions were also carried out with (Z)‐octadec‐9‐enoic acid, (Z)‐12‐hydroxyoctadec‐9‐enoic and (Z)‐9‐hydroxyoctadec‐12‐enoic acids. In addition, compound (I) was allowed to react with diphenyl methanol to form its corresponding ester. The structure elucidation of the prepared esters is based on the elemental analysis and spectral data (IR, ¹H‐ and ¹³C‐NMR, MS).