By-products of ethoxylation of simple alcohols in the presence of tripropylamine

Ethoxylation of simple alcohols such as methanol, ethanol and butanol in the presence of tripropylamine, in addition to the main reaction products, results in by-products from tripropylamine and ethylene oxide. This side-reaction consumes tripropylamine, forming dipropylamine ethoxylates and alcohol ethoxylates. These compounds remain in the product and influence the commercial properties of alcohol oxyethylates.     

Composition and interfacial activity of hydrophobic sulphide-type extractants

The composition and interfacial activity of dihexyl sulphide (Elf), dodecyl methyl sulphide (two samples from Elf and Penwalt) and n-dodecyl hydroxyethyl sulphide (Elf) which are commercially available sulphide-type extractants have been investigated. Recrystallized n-dodecyl hydroxyethyl sulphide was found to be of high purity (i.e. impurities, if any, are below the detection level of a gas chromatograph equipped with an efficient capillary column), whereas it was shown that all the other sulphides contained many components which were separated and, for most of them, indentified by a GC/MS technique. Recrystallized n-dodecyl hydroxyethyl sulphide starts to adsorb at the 2 M HCI/dodecane interface at concentrations (typically 10^?3 M ) of about one order of magnitude lower than dodecyl methyl sulphide (Elf or Penwalt). Dihexyl sulphide exhibits a very weak interfacial activity and the observed decrease in the interfacial tension in the system containing about 0·4 M dihexyl sulphide cannot be attributed with certainty to its own interfacial activity.     

COMPOSITION OF CYANEX® 923, CYANEX® 925, CYANEX® 921 AND TOPO

ABSTRACT

The composition of commercial reagents CYANEX® 923, CYANEX® 925, CYANEX® 921 and TOPO was investigated by GC/MS. CYANEX® 923 contains 18 components. 17 compounds were identified as trialkylphosphine oxides, mainly with normal (92.4) hexyl and octyl groups. CYANEX® 925 consists of 19 components. The reagent contains 65.9% kyphosphine oxides, mainly with isooctyl groups. The reagent contains also trialkylphosphine sulphides, dialkyldithiophosphinic acids and dialkyldisulphides having octyl and butyl groups. Trialkylphosphine sulphides and dialkyldithiophosphinic acids are present in amount of 26.8% be also considered as the active substance. CYANEX® 921 and TOPO are high quality reagents with the content of the active substance of about 99%. Trioctylphosphine oxide is the main component.     

Segmented MDI/HMDI‐based polyurethanes with lowered flammability

A series of segmented polyurethanes (PUs) based on 4,4′‐diphenylmethane diisocyanate and 1,6‐hexamethylenediisocyanate; polyoxypropylenediol (POPD); and low‐molecular chain extenders, 1,2‐propanediol or 3‐chloro‐1,2‐propanediol was obtained by solution polymerization and characterized by GPC and microscopic methods. Spherical aggregates with diameter of about 200 nm, arranged in a quasi‐linear mode, were observed by SEM technique; further investigations by the TEM method revealed hard‐segment domains of longitudinal shape, with length of about 5–10 nm, showing some features of the arrangement along a “director” axis. The process of thermal decomposition was monitored by thermogravimetric analysis in both dynamic and isothermal mode; to gain a deeper look into the mechanism of decomposition, kinetic analysis was performed. First, isoconversional methods showed a multistep decomposition route, as the value of (apparent) energy of activation changes from about 150 kJ/mol in the first step up to about 350 kJ/mol in the third step, which corresponds to the energy of dissociation of C? C bonds and leads to a char (carbonaceous) residue. Further calculations by means of the linear regression method revealed that kinetic model functions describing the degradation process of PU that does not contain chlorine were Bna → An → Fn, whereby for chlorine‐containing polyurethanes the CnB → An → An model was applied as best fit. Volatile products were investigated by pyrolysis–gas chromatography/mass spectrometry method at 770°C; the low molecular weight decomposition products, which were identified, indicate that the depolymerization process, yielding mainly diols and isocyanates through breakage of urethane bonds, prevailed during the thermal treatment under pyrolytic conditions. Finally, the mechanism of thermal degradation of modified polyurethanes with lowered flammability was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3214–3224, 2004