The Reactivity of Metals with Mixtures of Carbon Tetrachloride and Alcohols

Abstract

A1 reacts directly with the lower aliphatic alcohols only under anhydrous conditions at elevated temperatures or when amalgamated (1), or when highly stressed surfaces are freshly exposed (2). The reaction of Mg metal with moist ethanol at reflux is accelerated with the addition of small amounts of iodine or an aliphatic halogen compound such as chloroform or CC14. A1 and its alloys, brasses, bronzes, and iron alloys are subject to corrosion under some stringent conditions such as mechanical stress, high temperatures, or amalgamation (5-9). Some A1 alloys undergo a rapid, autocatalytic reaction with CCl4-methanol mixtures, initiated at room temperature and leading to complete dissolution of the metal (10). The corrosion of metals in halogenated hydrocarbons is currently under intensive study by Heitz and Kyriazis (11).My interest in this subject stems from reports of corrosion problems encountered in a brass thermal diffusion cell containing CC14-alcohol mixtures (12, 13). I report some novel leatures of this class of reactions. ExperimentalReactions in sealed tubes.--Separate 125 mg samples of Cu, Zn, Ag, Pt, and Au (each at least 99% pure) were sealed in NMR tubes with 500 mg of CCt4-methanol mixture (40% CC14, air not excluded) and held at 25~ Zn metal was decomposed overnight leaving a white solid and a colorless solution. Cu metal was consumed after two weeks leaving a yellow-brown solution and no solid residue. Ag metal was faintly discolored after two weeks but otherwise unaffected.Pt and Au remained bright with no visible indication of reaction. The course of the reaction with Zn and Cu was monitored with proton magnetic resonance spectra. Although the methyl and hydroxy proton signals were progressively shifted downfield (approximately 0.3 ppm in all) no new proton signal developed.In particular, nothing was seen which would indicate the formation of halohydrocarbons, aldehydes, or compounds containing methylene protons. The methyl and the hydroxy proton signals in the Cu tube were significantly broadened at the end of the reaction. When ethanol, 2-propanol, or 1-butanol were substituted for methanol, the reaction with Zn in sealed tubes was progressively more sluggish in order of increasing molecular weight of the alcohol and NMR spectra revealed no new proton signals which were not present at the beginning of the reaction. The induction period.--The time required for the initiation of a vigorous, autocatalytic reaction of Zn with CC14-methanol mixtures in open containers was sensitive to the composition of the mixture as well as to the presence of certain chemical initiators. This reaction was self-initiated at 25~ over a range of concentrations from 0.60 to 0.98 mole fraction of methanol. The minimum induction period, 2 hr, corresponded to a methanol concentration of approximately 0.90 mole Key words: corrosion, organic solvents, water. fraction when used with 30 mesh Fisher Reagent Grade Zn powder. The induction period was completely eliminated by adding traces of soluble salts of some less active me...

Orientational relaxation and vibrational excitation transfer in methanol–carbon tetrachloride solutions

“…In these sample cells, the solution came in contact only with the CaF 2 and Teflon, because metals such as copper catalyze the decomposition of alcohols in CCl 4 solution. 28 The laser system used in these experiments consists of a home built Ti:Sapphire oscillator and regenerative amplifier whose output pumps a three stage optical parametric amplifier ͑OPA͒ designed and built in house to produce linearly polarized, tunable mid-infrared light. A bandwidth limiting slit in the stretcher determines the bandwidth of the amplified seed pulse and provides control of the infrared ͑IR͒ pulse duration.…”

Structural dynamics of hydrogen bonded methanol oligomers: Vibrational transient hole burning studies of spectral diffusion

“…In these sample cells, the solution came in contact only with the CaF 2 and Teflon because metals, such as copper, catalyze the decomposition of alcohols in CCl 4 solution. 25 The laser system used in these experiments consists of a home-built Ti:sapphire oscillator and regenerative amplifier whose output pumps a three-stage optical parametric amplifier ͑OPA͒ designed and built in-house to produce tunable midinfrared light with controlled pulse duration ͑spectral bandwidth͒. A bandwidth limiting slit in the stretcher determines the bandwidth of the amplified seed pulse and provides control of the IR pulse duration.…”

Experimental Studies on the Approach to Steady State in Thermogravitational Diffusion

“…The length of the annulus in both apparatuses is identical and the two points from which samples are taken from the annulus for measurement of Δ Ware separated by 10.556 cm. The apparatus with the 0.65mm gap width is made of gold plated brass to prevent chemical reactions that produce HC1 in carbon tetrachloride-alcohol mixtures [23,24]. Such reactions are found to proceed slowly when these mixtures are in contact with unplated brass and proceed very rapidly in apparatuses constructed from iron alloys [24].…”

“…The apparatus with the 0.65mm gap width is made of gold plated brass to prevent chemical reactions that produce HC1 in carbon tetrachloride-alcohol mixtures [23,24]. Such reactions are found to proceed slowly when these mixtures are in contact with unplated brass and proceed very rapidly in apparatuses constructed from iron alloys [24]. The chemicals; carbon tetrachloride, cyclohexane, benzene, and methanol were spectranalyzed reagent from Fisher Scientific Company.…”