Pyrolysis of some amine salts of 2,4-dichlorophenoxyacetic acid

Abstract

was undertaken.Reagents. Commercial solid n-tetradecyl-and n-dodecylamines (Aldrich) and liquid n-butylamine were purified by vacuum distillation. Reagent grade dimethylamine (Eastman) was used without further purification. A 20% aqueous solution of methylamine was used for the preparation of the methylamine salt. Commercial 2,4-D (Aldrich) was recrystallized from benzene until a constant melting point of 140.3 ± 0.5°was attained.1:1 salts of 2,4-D were made by adding stoichiometric amounts of the amines dissolved in benzene-acetone solutions to solid 2,4-D at 10°. The solutions were shaken until all the 2,4-D had disappeared. The solvent was removed under vacuum at room temperature. The resultant salts were recrystallized from 1:1:1 ether-acetone-hexane until the melting points were constant.EXPERIMENTAL SECTION Pyrolysis Experiments. The solid salts were pyrolyzed in sealed Pyrex tubes covered with aluminum foil. Separate samples were pyrolyzed for 1 hr at temperatures from 30 to 200°. The tubes were then cooled before recording mass, infrared, and nuclear magnetic spin resonance spectra of the products.

Spectroscopic Analysis of Cotton Treated with Neutralized Maleinized Soybean Oil

“…Hee and Sutherland studied the pyrolysis of various amine salts of Cellulose i normalized spectra and ii subtraction spectra of 5 wt% maleamic acid a dried at 50°C for 30 min; b dried at 50°C for 30 min and cured at 160°C for 6 min; c dried at 50°C for 30 min, cured at 160°C for 6 min, and alkaline rinsed 2,4-dichlorophenoxyacetic (2,4-D) acid and observed that the dehydration of amine salts is impeded by longer chain lengths of the substituted amine [19]. The dimethyl amine salt of 2,4-D acid was more stable than the 2,4-D salts of primary amines such as methyl amine and n-butyl amine [19,20]. Carboxylate salts from ethanolamine and triethylamine are expected to be more stable than those of ammonia; indeed, salts from substituted amines were observed in greater quantities at 80 and 160°C (Fig.…”

Thermal Stability of Particle-Phase Monoethanolamine Salts

“…Finally, in addition to the reversible thermal dissociation into the MEA and acid (or acidic salt) counterparts, various irreversible intramolecular reactions may also take place inside the particles. For monocarboxylic acids, the pyrolysis of aminium salts at temperatures above ∼370 K causes reversible retrogradation, which is followed by nucleophilic attack of the amine on the carbonyl group of the acid, resulting in the water elimination and amide formation. , Amine salts with 2,4-dichlorophenoxyacetic acid are a good example, where amides are formed already at 353 K, peaking at 413–443 K, and decomposing completely above 473 K. In addition to amides, other compounds, including imines and lactones, are observed above ∼430 K . Relatively simple inorganic salts also can undergo irreversible decomposition on heating, e.g., ammonium sulfate in the first reversible decomposition step produces ammonium bisulfate, which subsequently decomposes irreversibly into ammonium pyrosulfate, sulfamic acid, sulfur dioxide, water, and molecular nitrogen. − Even in the case of dicarboxylic acid salts an additional pathway leading to the formation of the cyclic anhydride is possible at high temperatures .…”