Amine oxide stabilizers

Amine oxides show either nonionic or cationic behavior in aqueous solution depending on pH. In acid solution the cationic form (R2N" OH) is observed (2) while in neutral and alkaline solution the nonionic form predorninates as the hydrate R NO H2O. The formation of an ionic species in the acidic pH range stabilizes the form generated by the most studied commercial amine oxide, dimethyldodecylamine oxide (6). 

The surface active properties of aHphatic amine oxides were discovered ia the 1930s and the wetting, detergent, emulsion, and foam stabilizing properties were published shortiy thereafter (42). However, the use of amine oxides was not significant until Procter and Gamble started usiag them ia household products around 1960 (43—46). 

Examples of uses foi amine oxides include detergent and personal care areas as a foam booster and stabilizer, as a dispersant for glass fibers, and as a foaming component in gas recovery systems. Commercial suppliers of fatty amine oxides include Akzo Chemicals Inc. (Aromox) (73), Jordan Chemical Company (PPG Industries) (fordamox) (78), and Lonza (Badox) (79). 

Oligomeric hindered amine light stabilizers are effective thermal antioxidants for polypropylene. Thus 0.1% of A[,Af-bis(2,2,6,6-tetramethyl-4-piperadinyl)-l,6-hexanediamine polymer, with 2,4,6-trichloro-l,3,5-triazine and 2,4,4-trimethyl-2-pentaneainine [70624-18-9] (35) (Fig. 5), protects polypropylene multifilaments against oxidation when exposed at 120°C in a forced-air oven (22) for 47 days. 3,5-Di-/ l -butyl-4-hydroxytoluene [128-37-0] (0.1%) affords protection for only 14 days. 

Amine oxide pyrolysis occurs at temperatures of 100°-150°C. The reaction can proceed at room temperature in DMSO.323 If more than one type of (3-hydrogen can attain the eclipsed conformation of the cyclic TS, a mixture of alkenes is formed. The product ratio parallels the relative stability of the competing TSs. Usually more of the /f-alkene is formed because of the larger steric interactions present in the TS leading to the Z-alkene, but the selectivity is generally not high. 

In many instances it is not necessary to isolate the acetonitrile complex or to carry out the reaction in acetonitrile. The use of amine oxide as a means of displacing carbonyl groups in metal carbonyls is well documented, and reaction proceeds smoothly with the carbonyl in the presence of a variety of ligands—e.g., ethylene or pyridine—to yield the monosubstituted derivatives. The advantage of the acetonitrile adducts is the stability of the compounds and the reactivity of the amine oxide toward acidic ligands. 

Elimination to give a double bond conjugated with an aromatic ring is especially favorable. This presumably reflects both the increased acidity of the proton a to the phenyl ring and the stabilizing effect of the developing conjugation at the transition state. Amine oxides... 

Attempts have also been undertaken to improve the processability of PMR imide resins through molecular weight adjustments and exchange of the monomers employed. LARC 160 as an example here Jeffamine AP22, a eutectic blend of MDA type amines, was used as a polyamine instead of the crystalline MDA. This modification provided a quasi melt processable PMR resin (15). Other modifications were studied with the aim of improving the thermal oxidative stability by using hexafluoroisopropylidene dipthalic anhydride as a monomer (16). 

C capability. A resin coded AFR 700, based on a NE/HFDE/PPDA backbone with a stoichiometry imbalance, providing a prepolymer with a mixture of NE and amine/or anhydride endcaps, as is shown idealistically in Fig. 39. The thermal oxidative stability improvements vis a vis PMR-15 are presumably achieved because of a reduced aliphatic (NE) endgroup concentration. Unfortunately, no publication has appeared in the open literature on the mechanical performance of AFR-700 composition. 

A solventless PMR resin became known under the designation LARC 160 (15), which could be processed as a hot melt. An exchange of MDA in PMR-15 with a liquid isomeric mixture of di- and trifunctional amines (Jeffamine 22) provided a mixture of monomeric reactants which was tacky at room temperature. In the presence of 3% methanol the resin could be processed via a hot melt process. Unfortunately, the cured resin was inferior with respect to thermal oxidative stability in comparison to PMR-15. 

Ch.A. Lebailiff, FrP 1429285(1966) St CA 65, 12058(1966) [A compn, whose combustion velocity can be controlled is obtd by mixing a combustible (gelled hydrocarbons), an oxidizer (such as Amm nitrates, chlorates or perchlorates) and of an aq soln of a gum. Amines as stabilizers are added]... 

Light Stabilizers Pigments (carbon black, iron oxides), UV absorbers (hydroxyphenones, benzotriazoles), excited-state quenchers (organic Ni complexes), free-radical scavengers Hindered amine light stabilizers [piperidines, hindered amine light stabilizers (HALS)]... 

These alkyl dimethyl amine oxides are used as foam stabilizers primarily in light-duty liquids and shampoos where the major active ingredient is either an alcohol ether sulfate or an alcohol sulfate. The alkyl group is usually C19 to C.. which gives the best overall foam stability (3). 12 14... 

Improvement of the oxidative stability of silicone fluids is needed to extend their usefulness. It was recognized early (30) that some improvement could be obtained by using conventional hydrocarbon antioxidants—the aromatic amines and phenols. Such can be useful with DMS and MPS and are especially useful with alkyl (C H2n+i, n > 1) silicone fluids which are more comparable with alkanes in susceptibility to oxidation as n increases. 

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