Carbon-13 n.m.r. spectra of branched carboxylic acids and their derivatives

¹³C n.m.r. spectra have been measured for 39 compounds with branched structures including carboxylic acids, their methyl and ethyl esters, nitriles and chlorinated esters. The results obtained indicate that the ¹³ C n.m.r. technique is applicable to structure assignment of acids and their derivatives containing various numbers of substituents on the chain. The dependence of the carboxylic carbon chemical shift on the number and structure of α-positioned substituents has been determined. Calculation of the chemical shifts for branched carboxylic acids, esters and nitriles from the corresponding increments using the additivity scheme is shown to be possible in principle.     

Five ingol esters and a 17-hydroxyingenol ester from the latex of Euphorbia Kamerunica. Assignment of esters using 13C.N.M.R. methods.

The structures of five ingol esters and a 17-hydroxyingenol ester from the latex of $\text{Euphorbia kamerunica}$ have been determined. The ¹³C n.m.r. spectra of these compounds have been assigned using 2D δ_C/δ_H correlations. The specific positions of attachment of esters have been assigned unambiguously using ¹³C n.m.r. methods including 2D long range δ_C/δ_H correlation.     

Supercritical fluid chromatography of fish,shark and seal oils

Summary Various natural and treated fish, shark liver and seal oils have been analyzed by supercritical fluid chromatography (SFC) using a non-polar capillary column. The lipids are separated according to molecular mass. The lipid groups found included free fatty acids, cholesterol, squalene, vitamins, wax esters, cholesterol esters, diglycerides, triglycerides and ether lipids. Methods for the analysis of the marine oils depend on components present in the oil. When co-eluting lipid groups were present, modifications such as hydrogenation or TLC fractionation of the oils had to be made. In this paper applications of SFC on fish, seal and shark liver oils are presented.     

The effect of molecular geometry on the fragmentation of methyl esters of cyclobut-3-ene-1,2-dicarboxylic acids

Elimination of CH₃OH from the molecular ions of the methyl esters of cyclobut-3-ene-1, 2-dicarboxylic acids under electron-impact occurs to a much greater extent in stereoisomers having a trans configuration than in the cis analogues. Deuterium labelling shows that this process takes place via different mechanisms in the stereoisomeric esters. The abundance ratio [M ? CH₃OH]^˙+/[M ? CH₃O]+ is suggested as the most sensitive criterion for the deduction of configuration in this system. Determination of the geometry of the cyclobutene esters by n.m.r. spectroscopy as well as by pyrolysis to corresponding isomeric muconates is also discussed.     

The determination of wax esters in lube oil by infrared spectrometry

A simple and rapid method for estimating the content of wax esters in lubricating oils has been developed through the use of isopropanol extraction to concentrate the wax esters. The ratio of the absorption bands at 1740 and 1385 cm^-1 can be used directly for the determination of wax esters in lube oil samples. The method can be satisfactorily applied at levels down to 1 %, with an overall deviation of less than 10 %; for samples containing as low as 0.5 %, the procedure can be used semi-quantitatively with an error of about 20 %. This infrared method can also be used to determine marine and sulfurized wax esters.     

The origin of aromatic solvent-induced shifts in 19F n.m.r.

Aromatic solvent-induced shifts (ASIS) in ¹⁹F n.m.r. spectra of several organic fluoro compounds have been determined in several solvents. ¹⁹F n.m.r. signals of unsaturated fluoro compounds in C₆F₆ and C₆H₆ show excess high field shifts corresponding to the term σ_c (solvent shift caused by chemical interactions). The mechanism of this shift is discussed in connection with the presence of an F-π interaction. A thermal study also supports this idea.     

Fatty acid composition of neutral lipid: Classes of Citrus seed oil

The constituents of total lipids and neutral lipid classes, i.e., hydrocarbons, wax esters, sterol esters, triacylglycerols, free fatty acids, 1,3-diacylglycerols, 1,2-diacylglycerols, free sterols, alcohols, and monoacylglycerols of three species of Citrus namely Citrus sinensis, Citrus paradisi, Citrus aurantium were investigated by thin layer and gas chromatography. Palmitic, oleic and linoleic acids were the major components in all the lipids and lipid classes studied.     

Synthese von phenoxygruppenhaltigen Derivaten der Methandiphosphonsäure

Synthesis of Phenoxy Derivatives of Methanediphosphonic Acid Derivatives of the methanediphosphonic acid containing different numbers of phenoxy groups were prepared by Michaelis-Arbusov reaction of iodomethane phosphonic acid esters with phosphorous acid esters and by reaction of methane diphosphonic acid tetrachlorid with sodium phenolate. The obtained products were investigated by means of n.m.r. spectroscopy.     

Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. XXXIV. 27Al- und 1H-NMR-spektroskopische Untersuchungen an Lösungen des Systems AlCl3-Wasser-N,N-Dimethyl- formamid

Studies on Systems of Salts and Mixed Solvents. XXXIV. ²⁷Al and ¹H N.M.R. Spectroscopic Investigations of AlCl₃-Water-N,N-Dimethylformamide Solutions Al³⁺ ions exist in aqueous solutions as well as in DMF solutions in a sixfold coordination; the coordination of DMF exclusively occurs via the oxygen atom. Because of the small shift difference between the pure aqueous and the pure DMF solution at the ²⁷Al n.m.r. spectra no separated signals were found corresponding to the species with mixed coordination. From the changes of the Al chemical shifts and of the linewidths in dependence of the solvent composition a selective solvation process is suggested. At the ¹H n.m.r. spectra for the formyl and methyl protons of DMF separated signals appear for the molecules of the first coordination sphere and of the bulk, respectively. From this the number of directly coordinated DMF molecules can be determined. Up to a DMF content of about x = 0.45 DMF is preferentially coordinated, after that a change of selectivity takes place and accordingly water is preferred at the first coordination sphere.     

Smectic behaviour of methyl 4-alkoxybenzoates with a partially fluorinated alkyl chain

A series of 4-alkoxybenzoic acids 1[m,n] and their methyl esters 2[m,n] containing a partially fluorinated alkyl chain was prepared and their physical properties were investigated by optical, thermal and powder X-ray diffraction (XRD) methods. The former exhibits an SmC phase, while the latter form an SmA phase. XRD analysis indicated liquid-like character of the linking alkyl chains, and showed a decreasing layer thermal expansion coefficient from positive to negative upon increasing the degree of fluorination. The new esters 2[m,n] expanded the series and permitted analysis of trends in thermal stability of the SmA phase. The results demonstrate that the SmA–I transition temperature increases by about +20 K per CF₂CF₂ unit, and is destabilised by –5.6 K upon extending the hydrocarbon part by each CH₂CH₂ group. Data for the expanded series 2[m,n] were used for comparative analysis of mesogenic behaviour in two other series of derivatives of 1[m,n]. Synthetic methods for 1[m,n] and 2[m,n] are reviewed.     

Beiträge zur Chemie der Silicium–Stickstoff-Verbindungen. CXXX. Kernresonanz- und infrarotspektroskopische Untersuchungen an Methylaminosilanen

Chemistry of Silicon-Nitrogen Compounds. CXXX. N.M.R. and I.R. Spectroscopic Investigations on Methylaminosilanes The attachment of a silicon atom to methylamino groups leads in the pure compounds I to VII to a HNCH coupling constant for the protons of J = 6–7 Hz. A similar effect is also observed in solution, except in CH₂Cl₂ and CHCl₃. The correct assignment of the n.m.r. signals for IV is shown in Fig. 1. I to VII have practically the same basic properties as can be concluded from the invariable shift of the C? D stretching vibration of 35 cm^?1 for CDCl₃.     

Determination of isotope composition in protic solvents by cobal-59 nuclear magnetic resonance spectrometry

The very large chemical shift range provided by cobalt-59 yields well resolved lines for each of the nineteen isotopic species in the series of complexes ranging from Co(NH₃)³⁺₆ to Co(ND₃)³⁺₆ and each of the thirteen isotopic species in the similar series of tris(ethylenediamine)cobalt(III) complexes. The relative intensily distribution of these n.m.r. signals at equilibrium is related directly to the proton isotope composition of the solvent. This n.m.r. method of quantifying the isotope composition is examined with respect to the equilibrium isotope and the application to determination in aquerous and non-aqueous solvents.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Simultaneous Determination of 2- and 3-Monochloropropan-1,3-diol Esters in Foods by Enzymatic Hydrolysis and GC–MS Detection

A simple, reliable and accurate method for simultaneous determination of 2- and 3-monochloropropan-1,3-diol fatty acid esters (2- and 3-MCPD esters) in food by enzymatic hydrolysis and gas chromatography mass spectrometry was developed and validated. The extraction of lipids in food was conducted by mixed with hexane and homogenized for 2 min. After extraction, the lipids were directly transferred to enzymatic hydrolysis and the content was determined by gas chromatography mass spectrometry. The main advantage of the proposed method is that it can simultaneously analyse both 2- and 3-MCPD esters in foods and preserve their structural integrity. The limits of detection (LODs) of 2- and 3-MCPD esters in edible oil were 40 and 20 μg kg⁻¹ as 2- and 3-MCPD, respectively. For low fat foods containing less than 3 % fat, the LOD of 2- and 3-MCPD esters were lowered to 1.2 and 0.6 μg kg⁻¹ as 2- and 3-MCPD, respectively. Quantitative recoveries of different fatty acid esters of 2- and 3-MCPD esters were obtained after spiked corresponding standards into blank matrices.

     

Cyclometallation,part II. I.r. and1H N.m.r. studies of palladium(II) compounds with substitutedN-(benzylidene)amines

Summary New cyclometallated complexes of palladium containing substitutedN-(benzylidene)amines have been prepared and characterized. Palladium(II) acetate is used to make the acetato-bridged dimers, which undergo metathetical reactions to give the halo-bridged dimers. These when treated with PPh₃ or P(C₆H₁₁)₃ in a 12 molar ratio yield the phosphine monomers. I.r. and¹H n.m.r. studies show that palladium is coordinated through nitrogen, and also reveal the disposition of the halogen and phosphine ligands in the monomeric complexes.     

Borchelate und Bormetallchelate, 4. Mitt.

The i.r., u. v.,¹H n.m.r.,¹³C n.m.r., and¹¹B n.m.r. spectra of several substituted diphenylboron chelates derived from salicylaldehyde azomethines were compared with respect to the influence of the amine substituentR. O–B–N-6-ring constitution of the chelates29–32 [R=OH, NH₂, NHC₆H₅, N(CH₃)₂] can be deduced from the spectra.

Als 3. Mitt. gilt:F. Umland undE. Hohaus mit Beiträgen vonW. Riepe, K. Brodte, C. Schleyerbach undD. Szonn. Untersuchungen über borhaltige Ringsysteme vom Chelattyp. Forschungsbericht des Landes Nordrhein-Westfalen Nr. 2538. Opladen: Westdeutscher Verlag. 1976.     

29Si-MAS-NMR-Untersuchungen an kristallinen Bleisilicaten

Si-M.A.S.-N.M.R. Investigations on Crystalline Lead Silicates The isotropic ²⁹Si-n.m.r. chemical shifts of ten crystalline lead silicates with molar ratio PbO:SiO₂ between 4:1 and 1:1 has been measured. Starting from the known anion constitution the respective ²⁹Si-n.m.r. signals were assigned to silicate structure units (Qⁿ groups). Decreasing ratio PbO:SiO₂ corresponds to significant low-field shifts of the ²⁹Si-n.m.r. signals of definite Qⁿ groups with constant n. This result is of importance to the future investigation of crystalline and vitreous lead silicates with unknown anion constitution.     

N-Methyl-N-diäthoxyphosphorylamido-Derivate des Hexachlorocyclotriphosphazatriens. IV. NMR-spektroskopische Untersuchungen zur Konstitution der Ammonolyseprodukte von N-Methyl-N-diäthoxyphosphorylamido-chloro-cyclotriphosphazatrienen

N-Methyl-N-Diethoxyphosphorylamido Derivatives of Hexachlorocyclotriphosphazatriens. IV N.M.R. Spectroscopic Investigations of the Products of the Ammonolysis of N-methyl-N-diethoxyphosphorylamindo-chloro-cyclotriphosphazatrienes Broad band ¹H decoupled ³¹P n.m.r. spectra of products obtained by ammonolysis of N-methyl-N-diethoxyphosphorylamido-chloro-cyclotriphosphazatrienes provide essential hints at the constitution of these compounds. In this connection it may be easily demonstrated, both amino groups of N₃P₃Cl₃[NCH₃P(O)(OC₂H₅)₂][NH₂]₂ as well as of N₃P₃Cl₂[NCH₃P(O)(OC₂H₅)₂]₂ [NH₂]₂ are arranged geminally. The spectral parameters were found and verified by simulation of spectra. The simulated ³¹P spectra agree closely with the observed ones. The conclusions from the ³¹P n.m.r. spectra are complemented by these from the ¹H n.m.r. spectra.     

NMR-spektroskopische Untersuchungen an Mercaptophosphazenen. I. Verlauf der Reaktion von Natriumethylmercaptid mit Hexachlorocyclotriphosphazatrien bzw. Octachlorocyclotetraphosphazatetraen

N.M.R. Spectroscopic Investigations of Thiophosphazenes. I. Reactions of Sodium Ethylthiolate with Hexachlorocyclotriphosphazatriene and Octachlorocyclotetraphosphazatetraene By reactions of hexachlorocyclotriphosphazatriene with an excess of sodium ethylthiolate as a suspension in ether all of the possible geminal derivatives N₃P₃Cl_6?n(SEt)_n; n = 1–6, are formed in different quantities. Products from reactions of octachlorocyclotetraphosphazatetraene with sodium ethylthiolate, N₄P₄Cl_8?n(SEt)_n, likewise contain all of the geminally substituted derivatives up to n = 8 with the exception of the derivatives with n = 1 and n = 7. Compounds with n = 3, 4, or 5 exist in two geminal isomers respectively. Nongeminal ethylthiochlorophosphazenes were not found by any reaction. The formed compounds were isolated by chromatographic methods and studied by ³¹P n.m.r. spectroscopy.     

Reaktionen subvalenter Verbindungen des Siliciums mit Stickstoffheterocyclen

Reactions of Subvalent Compounds of Silicon with Nitrogenheterocycles Subvalent compounds of silicon were prepared from dichloro-bis(diethylamino)silane with Na/K alloy in hexane-dimethyloxyethane containing pyridine, 4, 4′-bipyridine, indole, chinoline, lepidine, isochinoline, mono-, di- or trimethylpyridine, N-methylindole or benzofurane. Products isolated from the reaction mixtures are formed either by the insertion of a Si(NEt₂)₂ unit (i) into a CH bond of methyl groups to give silanes RSi(NEt₂)₂H (with N-methylindole, sym-collidine), (ii) into a CN bond of the heterocycle expanding the six membered ring by one unit to give silazepines, or (iii) by the addition of a ClSi(NEt₂)₂ unit to the nitrogen atom of the aromatic heterocycle, which results in 1, 4-dihydro(chlorosilyl)pyridine derivatives. In the silazepines lithiation and subsequent reaction with (CH₃)₃SiCl occurs on a CH- or CH₂ group of the ring. Most compounds are characterized by elemental analyses, n.m.r. (¹H, ¹³C and ²⁹Si) and mass spectra; some have been identified by high resolution mass spectrometry and (or) characteristic signals in their n.m.r. spectra. X-ray structure analyses are provided for V and XX .