Phenothiazine derivatives as new antioxidants for the autoxidation of methyl linoleate and their reaction mechanisms

The effect of new antioxidants, such as phenothiazine derivatives, on the autoxidation of methyl linoleate was evaluated by estimating the induction period using the weighing method. Peroxide values (iodometry and IR), refractive indices, mol wts, and UV and IR spectra were measured to investigate the extent of the autoxidation. The induction period evaluated from the weighing method gives almost the same value as that from the peroxide values. It was shown that some new phenothiazine derivatives are remarkably effective antioxidants, and, besides, the mechanism for the autoxidation of methyl linoleate containing phenothiazine derivatives as antioxidants is probably of the same type as that for the substrate alone. This study also investigated the reaction mechanism of phenothiazine derivative antioxidants by determining the electron spin resonance spectra for the antioxidants in the autoxidation of methyl linoleate. Then, the following mechanism was proposed. That is, within the induction period, these inhibitors hold stable nitroxide radicals (>NO*) in the reaction between the antioxidant amino radical (>N*), produced by the reaction of the antioxidant with ROO* or O₂, and the peroxy radical (ROO*). Besides, the more superior the phenothiazine derivative antioxidant, the more inactive the antioxidant makes oxygen and the peroxy radical for the methyl linoleate autoxidation and also for the antioxidant oxidation. Presented at the 12th World Congress of ISF, Milan, 1974.     

Über die Autoxidation einiger asymmetrischer p-Dialkylbenzene

The Autoxidation of Some Asymmetric p-Dialkylbenzenes The autoxidation mixtures of p-ethyltoluene, p-isopropyltoluene, and p-ethylcumene were reduced with lithium alanate and the alcohols formed analyzed gaschromatographically. From the results obtained the relative reaction rates of primary, secondary, and tertiary C H-bonds with the chain-propagating peroxy radicals were estimated to 1 : 7 : 15.     

Photopolymerization of methyl methacrylate initiated by benzophenone/aromatic tertiary amines

Summary The photopolymerization of methyl methacrylate initiated by benzophenone-tertiary aromatic amines was studied under irradiation at 365 nm. The initiating amino radicals were investigated with combined ESR and spin-trapping method. The rate of polymerization for different amines was found in the sequence of p-hydroxymethyl-N,N-dimethylaniline>N,N-dimmethyltoluidine>N,N-dimethylaniline>p-methyl-N,N-dihydroxyethylaniline. The influence of diphenylmethanol on the polymerization reveals the incapacity of the benzophenone ketyl radical to initiate, while the amino end-group was detected in the polymers. This end-group can interact with benzophenone again, leading to initiate further polymerization to give a copolymer.     

Synthesis and trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate with diamines: a non-isocyanate route (NIR) to polyureas

A non-isocyanate route (NIR) of making polyureas of high molecular weight has been found through trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate (4,4′-DP-MDC) with a variety of diamines and mixed diamines. The preparation of 4,4′-DP-MDC was achieved readily by carbonylation of 4,4′-methylenedianiline (4,4′-MDA) with diphenyl carbonate (DPC) using organic acids as catalysts. It was found that the highest yield (99%) of pure 4,4′-DP-MDC can be isolated in a toluene solution under mild conditions co-catalyzed by benzoic acid and tertiary amine. Trans-ureation of 4,4′-DP-MDC with aliphatic amines indicated that the process is a highly solvent dependent process and was found to be extremely facile in dimethyl sulfoxide (DMSO) at 80 °C and in tetramethylene sulfone (TMS) at 140 °C in absence of any catalyst. Particularly, the most effective polymerization process was developed using tetramethylene sulfone (TMS) as the solvent under reduced pressure for concurrently distilling off phenol from the reaction mixture during the polymerization in a shifting equilibrium towards polyurea. However, this solvent-assisted trans-ureation was found to be in-efficient when N,N’-dimethyl-4,4′-methylenediphenylene biscarbamate (4,4′-DM-MDC) was used in a similar condition for comparison. Thus, an efficient green-chemistry process has been developed based on 4,4′-DP-MDC in making urea prepolymers, urea elastomers and urea plastics all in excellent yields without using reactive methylenediphenylene diisocyanate (MDI) or any catalysts in the trans-ureation polymerizations.     

Ion exchange resins and ethyleneimine polymer as antioxidants: I. Activity and mechanism

The antioxidant activity of ion exchange resins and ethyleneimine polymer was determined in methyl linoleate free from natural antioxidants and metals. Superior antioxidant activities were recognized in an ion exchange resin with NH groups and in the ethyleneimine polymer. The antioxidant activities in these heterogeneous reaction systems increased in linear proportion to the amount present. These antioxidant activities in the heterogeneous reaction system were mainly owing to their ability to donate hydrogen to the peroxy radicals produced in the autoxidation of methyl linoleate. The antioxidant radicals produced in these cases were very stable and generally couldn’t participate in the increase of the induction periods in the autoxidation of methyl linoleate by terminating the peroxy radicals. These results have never been obtained in the homogeneous reaction system but are characteristic in the heterogeneous one.     

The chemistry of lauric acid-diethanolamine condensation products

Summary The reaction of lauric acid with diethanolamine in the presence of excess alkylolamine results initially in the formation of N,N′-bis(2-hydroxyethyl)lauramide. This compound is responsible for the surface-active properties of the alkanolamides. Under the conditions of the reaction the amide undergoes a thermal rearrangement to the lauroyl ester of diethanolamine, which in turn is converted to the dilauroyl amido ester of diethanolamine. The excess diethanolamine converts both amino ester and amido ester to N,N′-bis(2-hydroxyethyl)lauramide.     

Soap based detergent formulations. V. Amphoteric lime soap dispersing agents

A series of amphoteric surfactants was prepared by the reaction of 1,3-propanesultone with fat derived primary amines, N-methylalkylamines, N,N-dimethylalkylamines, and N-acyl-N′,N′-dimethyl-1,3-propanediamines. Both mono- and disulfopropylated derivatives of the primary amines were synthesized. All compounds were found to be excellent lime soap dispersing agents. The quaternary sulfobetaines were found to possess the best detergency properties both by themselves and when formulated with tallow soap with or without sodium silicate builder. The detergency performance of such formulations is ca. the same as that of a commercial phosphate-built detergent. Presented at the AOCS Meeting, New Orleands, May 1973. ARS, USDA.     

Characteristic properties of cutting fluid additives derived from the adducts of diamines and acid chlorides

A number of N,N′-diacylalkyldiamines were prepared from the reaction of acid chlorides with 1,8-diaminooctane and 1,12-diaminododecane and screened for anti-rust properties and antimicrobial activity in spent coolants of water-based cutting fluids. Aqueous solutions of N,N′-dihexanoyl-1,8-diaminooctane and N,N′-isobutyroyl-1,12-diaminododecane showed good anti-rust properties for water-based cutting fluids. Aqueous emulsions of N,N′-dibutyroyl-, dipentanoyl-, dihexanoyl- and dioctanoyl-1,12-diaminododecane showed good lubricities and antimicrobial activity for water-based cutting fluids.     

Reactions of living polytetrahydrofuran with amines: 3. Secondary amines

Poly THF with terminal tertiary amine groups has been prepared from the following secondary amines: diethylamine, dicyclohexylamine, piperidine, diphenylamine and carbazole. The reaction of living polymer with aliphatic amines is rapid, but the slower reaction of the aromatic amines necessitates their prior conversion to the lithium salt. The products from the aliphatic amines elute somewhat later than expected from Styragel g.p.c. columns, but with an unchanged distribution, while polymer terminated by the aromatic amines behaves noormally. Poly THF terminated with diethylamine has been reacted with further living poly THF to yield a homopolymer with a quaternary ammonium grouping along the chain. It is also argued from g.p.c. traces that the same polymer tertiary amine quaternizes with a polystyrene bromide to give a block copolymer which fails to elute from the columns.     

Autoxidation of fatty acid esters in the presence of a heavy metal catalyst “Salcomine” (Co[II]-bissalicylalethylenedi-imine): II. Formation of a reaction product from a peroxy radical and salcomine

The formation of ionic Co(II)-bis-salicylalaethylenedi-imine complexes of peroxy radicals of methyl esters of fatty acids was followed by means of UV spectra. Typical compounds were isolated and purified, and analyzed for Co content. IR spectra were determined. The mechanism of the autoxidation of fatty acid methyl esters in the presence of “Salcomine” (Co[II]-bissalicylalethylene-di-imine) has been outlined, and its effect is explained as an oxidative addition reaction, resulting from coordinative unsaturation.     

Synthesis,optimization and characterization of PVA-co-poly(methacrylic acid) green adsorbents and applications in environmental remediation

Polymer Bulletin - The present paper is focused on the synthesis and optimization of a green PVA-co-poly(MAA) adsorbent by free radical polymerization using N,N′-methylene-bis-acrylamide and...     

Study of the coupling reactions between electrochemically generated aromatic radical anions and methyl, alkyl and benzyl radicals

Alkyl radicals produced in the indirect reduction of alkyl halides or alkyldimethylsulfonium salts by electrochemically generated aromatic radical anions couple fast with the latter and alkylated or dialkylated dihydro compounds are formed. Rate constants measured for the coupling reaction between on one hand methyl, primary, secondary and tertiary alkyl radicals as well as benzyl and cumyl radicals and on the other hand a wide spectrum of electrochemically generated aromatic radical anions are found to be about 1×10⁹ M⁻¹ s⁻¹. Previous measurements of coupling rate constants for primary alkyl radicals have been re-evaluated since they were affected by the presence of an S_N2 reaction occurring between the alkyl halides used as radical precursors and the aromatic radical anions. New experiments are also included using alkyldimethylsulfonium salts as precursors in order to prevent such S_N2 artefacts. It is concluded that sterical hindrance does not play a significant role for the radical-radical anion coupling reactions. In general the rate constants for the coupling reactions are all close to 10⁹ M⁻¹ s⁻¹.     

Fabrication and in vitro degradation study of novel optically active polymers derived from amino acid containing diacids and 4,4′-thiobis(2-tert-butyl-5-methylphenol)

Chiral bioactive poly(ester-imide)s (PEI)s were synthesized from N,N′-(pyromellitoyl)-bis-(L-phenylalanine) and N,N′-(pyromellitoyl)-bis-(L-leucine) diacids derived from amino acids with 4,4′-thiobis(2-tert-butyl-5-methylphenol) via direct polycondensation reaction in a system of tosyl chloride, pyridine and N,N-dimethylformamide as a condensing agent. The structures of these polymers were confirmed by FT-IR, ¹H-NMR, specific rotation, elemental and thermogravimetric analysis (TGA) techniques. TGA showed that the 10% weight loss temperature in a nitrogen atmosphere was more than 390 °C, which indicates that the resulting PEIs have a good thermal stability. The biodegradability of the monomers and prepared polymers was investigated in culture media and soil burial test for assessing the susceptibility of these compounds to microbial degradation. The results showed that the synthesized monomers and theirs derived polymers are biologically active and they are nontoxic to microbial growth.     

Model studies on the mechanism of hals stabilization

Hindered Amine Light Stabilizers (HALS) are know to inhibit the photo-oxidation of polymers. A key reaction in their stabilization mechanism is believed to be the conversion of a hindered aminoether into a nitroxyl radical. Several different possible mechanisms for this conversion were explored. One, the elimination of the aminoether to form an olefin and hydroxylamine (an intermediate in the formation of a nitroxyl), while possible at high temperatures, cannot account for the inhibitory activity we observed for secondary and primary aminoethers. Direct radical displacement by peroxy radicals was also considered. However, the products predicted by this reaction pathway were not observed. Finally, oxidation of the nitrogen by a peroxy radical, by either electron transfer or a radical attack on the nitrogen, was investigated. While electron transfer was shown to be unlikely, direct oxidation of the aminoether nitrogen was supported by our results. A detailed mechanism for the reaction of both alkyl- and acyl-peroxy radicals with aminoethers is proposed.     

Fluorescent products of lipid peroxidation: I. Structural requirement for fluorescence in conjugated schiff bases

The structural requirement for fluorescence in Schiff bases was defined. Aldehydes and amines were reacted and the structures of the Schiff bases N-hydroxyethyl-1-imino-2′,4′-hexadiene (I), N-1-benzal-2-hydroxyaminoethane (II), and N-1-benzal-2,2′-hydroxyaminoethane (III) were established by elemental analysis, IR spectral analysis and mass spectral analysis. The structures of N-alanyl-2-hydroxy-naphthylidine (IV) and N,N′-dileucinyl-1-amino-3-iminopropene (V) had been established previously. III, IV and V were fluorescent compounds and I and II were not. The results of these analyses suggest that an electron donating group in conjugation with an imine is the structure required for fluorescence.     

Synthesis of well-defined norbornene–lactone-functionalized polymers via ATRP

Well-defined norbornene–lactone-functionalized polymers were synthesized by atom transfer radical polymerization (ATRP) of 5-methacryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (MNL) and 5-acryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (ANL) monomers. The ATRP of MNL initiated by ethyl 2-bromopropionate (EBrP), in both N,N-dimethylformamide (DMF) and o-dichlorobenzene (ODCB) solvents was successfully carried out in the presence of CuCl/CuBr and N,N,N′′,N′′,N′′-pentamethyltriethylenetetramine (PMDETA) at 70 °C. The CuCl/ODCB catalyst system gave rise to a lower M _w/M _n (≦1.20) than CuBr/DMF catalyst system. The ATRP of ANL was feasible in the presence of CuBr and PMDETA at 70 °C but showed lower reactivity than MNL. The resulting polymers were characterized by means of gel permeation chromatography (GPC) and ¹H NMR spectroscopy.     

Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen

The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH₄, and the alcohols formed were determined by gas chromatography. In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved. On the basis of the analytical results relative reaction rates of the various C–H-bonds in the hydrocarbons studied were calculated. It is shown that the attack at C–H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.     

Curing of epoxy resins with amines

Summary Using determination of the critical molar ratio of functional groups necessary for gel formation with amino groups in excess, network formation was investigated in the reaction of diglycidyl ether of Bisphenol A (DGEBA) and nitrogen-containing epoxy resins — diglycidylaniline and N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane with aromatic or aliphatic amines. It was found that in the case of nitrogen-containing epoxides the crosslinking is accompanied by pronounced cyclization, unlike in systems with DGEBA. Gelation depends on the relative reactivity of the primary and secondary hydrogen atom of the amino group. In the case of nitrogen-containing polyepoxides, the dependence of reactivities of adjacent glycidyl groups is also operative.     

Determination of primary and secondary fatty aliphatic amines in the presence of large amounts of nitrile by near-infrared spectroscopy

There are numerous methods proposed for determination of primary, secondary and tertiary amines. Most seem to be lengthy, inaccurate and unsuitable for small samples. Previous spectroscopic methods based on near-infrared spectroscopy for determination of aliphatic and aromatic amines are not applicable for samples containing more than 10% nitrile. A simple method based on near-infrared spectroscopy has been developed, and is presented, for determination of primary and secondary fatty aliphatic amines in the presence of 0–100% nitrile.     

Investigations into the AIBN initiation steps in the free radical polymerisation of acrylonitrile by the aminoxyl trapping technique

Summary A modification of the radical trapping technique employing the stable nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-1 H-isoindol-2-yloxyl, has been used to study the reaction of cyanoisopropyl radicals with acrylonitrile. By keeping the concentration of the aminoxyl radical very low (strategically added via a syringe pump), the addition of acrylonitrile to cyanoisopropyl radicals becomes competitive with radical trapping. Thus, sufficient quantities of alkoxyamines produced by the trapping of second generation carboncentred radicals (cyanoisopropyl plus one monomer unit), and even third generation carbon-centred radicals were obtained for identification by HPLC/MS techniques. Trapping by traces of adventitious oxygen was also competitive and the various peroxy radicals thus formed, underwent addition to acrylonitrile followed by further reaction or trapping by the aminoxyl. *** DIRECT SUPPORT *** AEB03077 00003