Rhodium‐Catalyzed Homogeneous Reductive Amidation of Aldehydes

The catalytic reductive amidation of an aldehyde (hexanal) with an amide (acetamide) is reported. Apart from the desired N‐hexylacetamide, the two isomeric unsaturated intermediates as well as hexanol are produced together with higher mass products that arise from aldol condensation and diamide coupling of the aldehyde. Screening of different catalyst precursor salts, ligands and reaction conditions led to the finding that the catalytic system based on the (cyclooctadiene)rhodium chloride dimer, [Rh(cod)Cl]₂, in combination with the ligand xantphos and an acid co‐catalyst results in high selectivity for the desired product. Under optimized conditions nearly full conversion is reached with high selectivity to the desired N‐alkylamide and with a very high N ‐ alkylamide/alcohol ratio, while producing only small amounts of by‐products. The scope of the reaction has been investigated using different amides as well as aldehydes; the results show the general applicability of this novel reaction, but with electron‐withdrawing amides the selectivity to N‐alkylamide is lower. NMR studies showed that the nucleophilic addition of acetamide to hexanal is acid catalyzed, forming N‐(1‐hydroxyhexyl)acetamide in equilibrium with both hexanal and the dehydrated unsaturated imides. A catalytic mechanism is proposed in which a strong acid such as HOTs acts as a co‐catalyst by establishing a rapid chemical equilibrium between the aldehyde, acetamide and the intermediates. Furthermore, it is proposed that the presence of acid causes a change in catalytic species, enabling a cationic Rh/xantphos hydrogenation catalyst to selectively hydrogenate the intermediates to N‐hexylacetamide in the presence of hexanal.     

The Preparation and Acid-Catalyzed Decomposition of N-Triphenylmethyl Amides

Aliphatic and aromatic primary amides react with triphenyl methanol in the presence of small amounts of sulfuric acid in acetic acid, and N-triphenylmethyl amides are obtained in good yields. The products are cleaved by acids. The decomposition of four N-trityl amides was studied in various mixtures of acetic acid-sulfuric acid, and the correlations between the logarithms of the observed first-order rate coefficients, the concentration of the sulfuric acid, and the acidity functions H_O and H_A were studied. The kinetic data support a unimolecular rate-determining step for the solvolysis.     

A new protonation chemistry of phosphazenes and the formation of bis(sulfonyl)imides

The protonation of N-sulfonyl trichlorophosphazenes (R¹-NPCl₃) with sulfonic acids has been successfully utilized as a facile synthesis route for bis(sulfonyl)imides. It was also found that the formation of protonated imides is strongly affected by the acid strength of the proton donors and the N-substituents (R¹). When R¹ is a good leaving group, a hitherto unobserved protonation chemistry occurs, producing a series of mixed sulfonylphosphonylimides. A tentative rationale is proposed for the novel chemistry of phosphazenes.     

5-Hydroxy fatty acid amides from δ-lactones and alkyl glucamines

δ-Lactones derived from unsaturated fatty acids are useful precursors to fatty amides due to their enhanced reactivity. Consequently, temperature-sensitive glucamines were easily converted to their 5-hydroxy fatty acid amides in high yield (52–97%) by reaction with C₁₈ and C₂₀ δ-lactones. High yields of amides (52–97%) were obtained with little or no solvent at 90°C in less than 24 h. C₁₈ δ-lactones were more miscible in the glucamine than the C₂₀ δ-lactones and thus increased reaction rates and yields of amides. In addition, amidation reactions run in the absence of catalyst gave good yields, whereas reactions in the presence of base catalysts completely inhibited the reaction. The 1-(N-alkyl-5-hydroxy fatty acid amido)-d-glucitols are expected to have useful properties as biodegradable components in detergents.     

Thiosubstituted Organophosphorus Acids as Selective Extractants for Ag(I) from Acidic Thiourea Solutions

Abstract

This paper deals with the solvent extraction of silver from thiourea leaching Ag ore liquors as an alternative to the traditional process involving cyanide. The investigation of the extraction mechanism of silver from acidic thiourea solution had not been clearly established to date.

The extraction behavior of silver using di(2‐ethylhexyl)dithiophosphoric acid (D2EHDTPA) and di(2,4,4‐trimethylpentyl) thiophosphinic acid (CYANEX 302) was studied. The effect of various parameters such as concentrations of metal, mineral acid, thiourea, and extractant has been investigated. The extracted complexes have been identified through a slope method analysis as AgX(HX)₅ for CYANEX 302 and AgX for D2EHDTPA, where HX denotes the extractant. Moreover, complete stripping was ensured with a mixture of NH₄SCN and H₂SO₄. In addition we showed that a first step of extraction with D2EHPA or CYANEX 272 results in the preferential separation of Fe(III) from the Ag(I) leach solution.     

3, 4‐Dihydroxymandelic acid amides of alkylamines as antioxidants for lipids

The antioxidative and radical scavenging activity of the 3, 4‐dihydroxymandelic acid (DHMA) amides of hexylamine, 2‐ethylhexylamine, octylamine, and cyclohexylamine was determined by several physicochemical test systems. The amides were synthesized by protecting group‐free coupling of in situ prepared N‐hydroxysuccinimidylester of DHMA and the amines. The radical scavenging activity was determined using the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) method and by quenching superoxide anions generated using a horse radish peroxidase/H₂O₂ system. In the DPPH assay, all amides show higher radical scavenging activity (EC₅₀ 0.09‐0.12 mol/mol_DPPH) compared to the standard antioxidants ascorbic acid (EC₅₀ 0.27 mol/mol_DPPH) and tocopherol (EC₅₀ 0.25 mol/mol_DPPH). The amides are also more potent superoxide radical scavengers (IC₅₀ < 600 nm) than standard ascorbic acid (IC₅₀ 700 nm). Activity against lipid peroxidation was determined by accelerated autoxidation of highly unsaturated oils and squalene using the Rancimat. Again, the antioxidative potentials of the DHMA amides against lipid oxidation as determined by the Rancimat, are at least equal or higher compared to the standard lipid antioxidants tocopherol, BHT, BHA, and ascorbylpalmitate (concentration in soybean oil 0.05%, all other oils 0.025%, squalene 0.005%). In squalene, an equi‐amount mixture of DHMA octylamide and α‐tocopherol shows a synergistic effect. Last but not least, the amides are able to protect an emulsion of linoleic acid/β‐carotene against oxidation initiated by N, N‐azodiisobutyramidine dihydrochloride (IC₅₀ 0.19‐0.77 mmol/l, ascorbic acid > 0.9, tocopherol 0.08). The DHMA octylamide in combination with ascorbic acid shows a synergistic antioxidative effect in the emulsion model. In conclusion, the new alkylamides of DHMA are easy to synthesize, potent radical scavengers and protect lipids, in particular the highly unsaturated, both in bulk and in emulsions against autoxidation.     

Konformation und Rotationsbarrieren substituierter Glyoxylsäureamide

Conformation and Rotation Barriers of Substituted Glyoxylic Acid Amides Semiempirical calculations predict an orthogonal orientation of the carbonyl groups in tertiary glyoxylic acid amides, which is in good agreement with an X-ray structure analysis of 5 . Due to the influence of the α-carbonyl group, the rotation barrier in the substituted glyoxylic acid amides 2a–d, 3a, 3b , and 4–6 (ΔG^#_c = 84–92 kJ mol⁻¹) is about 10 kJ/mol higher than in simple acid amides, as was found by dynamic NMR line shape analysis.     

Synergistic Effects of Amides from Two <Emphasis Type="Italic">Piper</Emphasis> Species on Generalist and Specialist Herbivores

Plants use a diverse mix of defenses against herbivores, including multiple secondary metabolites, which often affect herbivores synergistically. Chemical defenses also can affect natural enemies of herbivores via limiting herbivore populations or by affecting herbivore resistance to parasitoids. In this study, we performed feeding experiments to examine the synergistic effects of imides and amides (hereafter “amides”) from Piper cenocladum and P. imperiale on specialist (Eois nympha, Geometridae) and generalist (Spodoptera frugiperda, Noctuidae) lepidopteran larvae. Each Piper species has three unique amides, and in each experiment, larvae were fed diets containing different concentrations of single amides or combinations of the three. The amides from P. imperiale had negative synergistic effects on generalist survival and specialist pupal mass, but had no effect on specialist survival. Piper cenocladum amides also acted synergistically to increase mortality caused by parasitoids, and the direct negative effects of mixtures on parasitoid resistance and pupal mass were stronger than indirect effects via changes in growth rate and approximate digestibility. Our results are consistent with plant defense theory that predicts different effects of plant chemistry on generalist versus adapted specialist herbivores. The toxicity of Piper amide mixtures to generalist herbivores are standard bottom-up effects, while specialists experienced the top-down mediated effect of mixtures causing reduced parasitoid resistance and associated decreases in pupal mass.     

Synthesis and properties of nonlinear optical polymers based on poly(ether imides) for electrooptical devices

Summary : Nonlinear optical poly(ether imides) with an adequate thermal stability has been synthesized by direct coupling of hydroxy poly(ether imides) and NLO chromophores with a quantitative yield. The resultant amorphous NLO poly(ether imides) exhibited good solubility in common organic solvents, providing optical-quality thin films by spin coating. The glass transition temperatures of the polymers are at around 180 °C. The electrooptic coefficients (r₃₃, @1.3μm) of PEI-DR1 was 12.3 pm/V with an electrical poling field of 100 V/μm and it decayed about 10 % over 10 months at 90 °C under atmospheric conditions. Received: 23 February 1999/Revised version: 26 March 1999/Accepted: 29 March 1999     

Structure/performance characteristics of bisamide lubricants in ABS

A number of bisamides were synthesized using fatty acid chain lengths varying from C₄ to C₂₂. Nonsymmetric as well as symmetric amides were prepared. The diamines from which these amides were prepared included ethylenediamine, butylenediamine, and 1,6 hexamethylenediamine. Properties of the pure bisamides and their effect in ABS polymers were measured. These properties included melting points, DTUL, impact, spiral flow, and color.     

Sulfonated poly(ether imide) and poly(ether sulfone) blends for direct methanol fuel cells. I. Sulfonation of PEI and characterization of the products

This investigation examines characteristics of sulfonated polyether imides (SPEI) with various ion exchange capacity values (IEC) and completes previous work to enable its blends to be adopted as polyelectrolyte in direct methanol fuel cells (DMFC). Polyether imides (PEI) were sulfonated by using chlorosulfonic acid as the sulfonating agent and chloroform as the solvent. The structure of SPEI was observed by FTIR and ¹H NMR. The sulfonate or sulfonic acid content of the polymers, expressed as a number per repeat unit of the polymer, was accurately determined by elemental analysis and conductometric titration. Physical properties such as solubility, intrinsic viscosities, thermal stability, and glass transition temperature (T_g) were studied for both PEI and SPEI. TGA‐FTIR verified that sulfonic groups, attached to the aromatic ring in the PEI backbone, are split at 230–350°C, but the main‐chain splitting temperature of SPEI is similar to that of pure polymer. The sulfonated samples exhibited good solubilities and increased glass transition temperatures (T_g values) as degree of sulfonation (DS) increased; two T_g values were detected when IEC was sufficiently high. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

SYNERGISTIC EFFECTS IN SOLVENT-EXTRACTION SYSTEMS BASED ON ALKYLSALICYLIC ACIDS. I. EXTRACTION OF TRIVALENT RARE-EARTH METALS IN THE PRESENCE OF ALIPHATIC AMIDES

ABSTRACT

Aliphatic carboxylic acid amides were found to cause synergistic shifts in the pH₅₀values for the extraction of the trivalent rare-earth metals from chloride media by solutions of alkylsalicylic acids in xylene. For the different types of amide examined, the synergistic shifts for the extraction of neodymium by 3,5-diisopropylsalicylic acid (DIPSA) generally decrease in the order : R.CO.NR₂’ > R.CO.NHR’ > R.CO.NH₂, where R and R’ are alkyl groups. With the N,N-dialkyl amides (R.CO.NR₂’) and the W-alkyl amides (R.CO.NHR’), the extent of the synergistic effect decreases with increasing chain-branching in either of the alkyl groups R and R’. For additions to 0.25 M alkylsalicylic acid, the synergistic effect increases with concentrations of up to 0.1 M amide, and decreases with higher concentrations. The extent of the synergistic shift produced by a given amide, as well as the separation in pH₅₀ values from lanthanum to lutetium, increases with increasing steric bulk of the alkylsalicylic acid used. The separations between adjacent lanthanides are too small to be of any practical interest, however. Measurement of the solubility of salicylic acids (HA) in xylene containing various amounts of N,N-daalky amide (L) indicate that essentially complete formation of the HA.L adduct takes place. Treatment of metal-distribution data by slope analysis, and measurement of the solubility of the neodymium-DIPSA complex in xylene in the presence of amide suggest that the mixed-ligand complex has the stoichiometry NdA₃L₂.     

Organoarsen-Verbindungen. XXVI. Zur Synthese der 1.3-Azarsoline

Organo-arsenic Compounds. XXVI. Synthesis of 1.3-Azarsolines 2-Aminoalkylarsines of the type RAs(H)CH₂CH₂NH₂ react with formic acid or carbonic acid chlorides to give the corresponding amides 1–3 , whereas reaction with iminoester hydrochlorides yields 1,3-azarsolines 4–6 . I. R.- and n.m.r.-data are reported.     

Studies on the synthesis and properties of soluble homo- and copolyester–imide derived from imide–diacid

A series of polyester–imides was prepared from diacid (imid–diacid [ M1–M4 ] or a mixture of imide–diacid and terephthalic acid [TPA]) and bisphenol A in the presence of diphenyl chlorophosphate (DPCP) and pyridine as a direct condensation agent. The inherent viscosites of homo- and copolyester–imides were in the range of 0.39–0.58 dL/g. Almost all these homo- and copolyester–imides were completely soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), dimethylformamide (DMF), and m-cresol. The thermal properties of homo- and copolyester–imides were examined by DSC and TGA. These copolyester–imides had glass transition temperatures in the range of 95–240°C and a 5% weight loss was observed in the range of 354–465°C. © 1995 John Wiley & Sons, Inc.     

Anodic oxidation of N-anions. III. Anodic oxidation of the N-anions of diacylimides: A search for a new electrochemical synthesis of hydrazine

The anodic oxidation of N-anions of diacylimides which are acidic enough to be deprotonated by relatively weak bases in protic solvents was investigated with respect to the electrode kinetics and preparative aspects. All imide anions are oxidized in a one-electron step to the respective imide radicals. Of the imides investigated, two were cyclic carboxylic imides (succinimide and phthalimide) three were sulphonyl imides (di-p-toluene and di-benzene sulphimide, dimethane sulphimide) and one was a mixed carboxylate-sulphonate imide (saccharate). The imide radicals produced by anodic oxidation of the dicarboxylate imides do not couple to form a hydrazine derivative but induce solvent oxidation by H-abstraction. The disulphonyl imides couple to unstable hydrazine derivatives although H-abstraction occurs to more than 80%. Only the anodic coupling of the N-anion of imido-disulphonic acid to hydrazine tetrasulphonate discovered by Grinstead [3] can be performed with good selectivity and current and mass yields. The optimum conditions for this reaction are determined in order to show that it may serve in the future as one step in a new hydrazine process.For parts I and II see [1] and [2].     

Highly selective asymmetric synthesis of 2-hydroxy fatty acid methyl esters through chiral oxazolidinone carboximides

Highly selective asymmetric synthesis of 2-hydroxy fatty acid methyl esters has been accomplioshed through chiral imide enolates. Five chiral oleic acid imides were prepared by reaction of oleioc acid with pivaloyl chloride followed by reaction with five different lithiated chiral oxazolidinones including (R)-(+)-4-benzyl-2-, (S)-(-)-4-benzyl-2-, (4R,5S)-(+)-4-methyl-5-phenyl-2-, (4S,5R)-(-)-4-methyl-5-phenyl-2-, and (R)-(+)-4-isopropyl-2-oxazolidinones in 88–92% yileds. The chiral imides were reacted with NaN(Me₃Si)₂ at −78°C to give enolates, which subsequently reacted with 2-(phenylsulfonyl)-3-phenyloxaziridine to give hydroxylated products in 78–83% yields. Methanolysis of the hydroxylated products with magnesium methoxide gave methyl 2-hydroxyoleate. Enantiomeric excesses (ee) of the products were determined to be very high (98–99% ee) by ¹H nuclear magnetic resonance study after esterification of the hydroxy group with (S)-(+)-O-acetylmandelic acid. Enantioselective hydroxylation of other fatty acids including elaidic, petroselinic, vaccenic, and linoleic was evaluated under the similar conditions using (4R, 5S)-(+)-4-methyl-5-phenyl-2-oxazolidinone as a chiral auxiliary to give 98% ee values for all cases.     

SOLVENT EXTRACTION OF URANIUM( VI) AND THORIUM( IV) FROM NITRATE MEDIA BY CARBOXYLIC ACID AMIDES

ABSTRACT

A series of nineteen N-alkyl carboxylic acid amides (R.CO.NHR') has been prepared, in which the alkyl groups R and R' have been varied in order to introduce different degrees of steric complexity into the compounds. A smaller number of N,N-dialkyl amides (R.CO.NR₂) and non-substituted amides (R.CO.NH₂) has also been prepared for comparison purposes. These amides were characterized by measurement of their boiling points, melting points, refractive indices and densities.|The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate media by solutions of the amides in toluene was studied. Increasing steric bulk of the alkyl groups R and R' was found to cause a marked decrease in the extraction of thorium, with a much smaller effect on the extraction of uranium, thus considerably enhancing the separation between these metals. Vapour pressure osmometry studies indicate that the N,N-alkyl amides are self-associated in toluene solution, with aggregation numbers up to about 2.5 for 0.6 M solutions at 35°C. In contrast, the N,N-dialkylamides behave as monomers under these conditions. The distribution ratios for the extraction of uranium and thorium show second- and third-order dependences, respectively, on the extractant concentration for both the N-alkyl and N,N-dialkyl amides.     

SYNTHESIS AND USES OF THE AMIDES EXTRACTANTS

Carboxylic acids amides (RR' NCOCR” ) malonic acid amides ( RR' NC0CH₂ C0NRR' ) and substituted malonic acid amides ( RR,NC0CHR“ C0NRR ) are extractants of the actinides ions. They show good prospects for use in the nuclear industry because of their complete incinerability. In addition, their degradation products interfer much more less in the separation processes when compared with organophosphorus extractants. The synthesis and the purification of two typical extractants: N-N-di( 2-ethylhexyl) butyraraide ( C₄H₉ CHC₃H₅CH₂) NC0C₃H₇and N,N' -dimethyl N,N' -dibutyl 1,3 diamide 2( 3-oxa) nonyl propane ( C₄H₉CH₃NC0) ₂CHC₂H₄OC₆H_1,3 are described. The purities, checked by NMR, elemental analysis and potentiometry, were in the range 98 to 99.5% The yields for monoamides were in the range 70 to 90% and for the diamides 20 to 40%     

Oxygen electroreduction in perfluorinated sulphonyl imides

The electroreduction of oxygen in perfluorinated sulphonyl imides has been studied with the emphasis on the identification of alternate acid electrolytes which could replace the presently used phosphoric acid as an electrolyte in H₂–O₂ fuel cells. The activity for oxygen reduction on smooth platinum and gas-fed, high surface area platinum-catalysed electrodes (10% platinum loading on XC-72 carbon support) has been examined. The polarization of the air cathode in the micro-fuel cell in bis(trifluoromethanesulphonyl)imide is 40 mV more positive compared to phosphoric acid at 100 mA cm^–2, presumably due to the increased solubility of oxygen and lower tendency of bis(trifluoromethanesulphonyl)imide to adsorb on the platinum catalyst. The related bis(fluorosulphonyl)imide is unstable in water and the hydrolysis products adsorb strongly on the catalytic sites, resulting in poor performance.     

Surface active agents from isopropenyl esters: Acylation of isethionic acid and N-methyltaurine

Acylation of sodium isethionate with isopropenyl stearate at 200 C for 30 min gave a 95% yield of sodium 2-sulfoethyl stearate, acetone being the only byproduct. Acylation of N-methyltaurine at 200 C for 90 min gave a 95% yield of N-methyl-N-(2-sulfoethyl) stearamide sodium salt. Corresponding surface active derivatives were also prepared from pelargonic, lauric, myristic, palmitic, oleic, phenylstearic and hydrogenated tallow fatty acids from their respective isopropenyl esters. Detergency, foam height, wetting time, lime soap dispersing power, critical micelle concentration and other surfactant properties were evaluated. Optimum properties were found at the C₁₄−C₁₈ fatty acid chain length. Unsaturation or branching increased solubility. The 2-sulfoethyl esters were similar to the N-methyl-N-(2-sulfoethyl) amides in foam height, wetting ability and lime soap dispersing power, superior to the N-methyl-N-(2-sulfoethyl) amides in detergency, but inferior in calcium stability and less stable to acid and alkali. Both compounds are readily biodegraded. The fatty isopropenyl ester synthesis has an advantage in yield and purity of the product and could increase the utilization of the 2-sulfoethyl esters and N-methyl-N-(2-sulfoethyl) amides in many applications. Presented at the ISF-AOCS Meeting in Chicago, September 1970. Deceased. E. Mark. Nutr. Res. Div., ARS, USDA.