Tuning fluid solvents for chemical reactions

Eckert, Charles A.; Chandler, Karen

doi:10.1016/s0896-8446(98)00051-5

Cited by 57 publications

(45 citation statements)

References 33 publications

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“…Common acids include Brønstead acids such as HCl, H 2 SO 4 and H 3 PO 4 and Lewis acids such as AlCl 3 and BF 3 . Problems such as large amounts of waste, toxicity, corrosion, and difficulty of separation plague acids used in industry.…”

Section: Introductionmentioning

confidence: 99%

Self-neutralizing in situ Acid Catalysts from CO2

et al. 2006

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Acids are the most common industrial catalysts but have the disadvantage of requiring post-reaction neutralization and salt disposal. We show the catalytic use of self-neutralizing acids. Carbon dioxide interacts with water and amines to form carbonic acid and carbamates. A similar interaction occurs with alcohols to form alkylcarbonic acids. All three solvent systems provide in situ acid formation for catalysis which can be easily neutralized by removal of carbon dioxide. However, water has poor organic solubility and amines form salts so only alkylcarbonic acids combine good organic solubility with simple neutralization via depressurization. The use of in situ acid also completely eliminates the solid salt wastes associated with many acid processes. To elucidate how to implement these systems in place of a standard acid system we compare the reaction rates of several alkylcarbonic acids with diazodiphenylmethane (DDM). We report also the effect of CO 2 pressure on reaction rate of DDM as well as measure the dielectric constant of these systems. Finally, a Hammett plot is used to identify the dominant step in alkylcarbonic acid catalysis.

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Section: Introductionmentioning

confidence: 99%

Self-neutralizing in situ Acid Catalysts from CO2

et al. 2006

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“…It has been demonstrated that these solvents systems are useful for coupling reactions and separations. (Dillow et al [1], Eckert et al [6], Daintree et al [19], Eckert et al [20], Eckert and Chamber [21], Eckert et al [22,23], Jessop [24], Ramsey et al [25], Rayner [26], Rezaei et al [27], Tang et al [28]) In contrast, switchable solvents are solvents that change physical properties abruptly. In other words, they can be switched "on" and "off".…”

Section: Introductionmentioning

confidence: 99%

Solvents for sustainable chemical processes

Pollet

Eckert

Liotta

2011

WIT Transactions on Ecology and the Environment

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Worldwide, socioeconomic strategies encourage -and may soon enforceindustrial sustainability. Therefore, innovative research and approaches must provide short and long term solutions to reach future legislative targets. For chemical processes, the development of solvents that facilitate reaction and subsequent product separation is paramount to secure economic competitivity while minimizing impact on the environment and energy consumption. Tunable and switchable solvents were developed to address synergistically reaction and separation. Tunable solvents change properties continuously upon application of an external stimulus. For example, organic aqueous solvents allow for the reaction to be homogeneously catalyzed followed by a simple and efficient heterogeneous separation of the product (commonly a heterogeneous catalysis attribute). Chemical processes mediated by water at or below the near critical range can also alleviate the shortcomings of current synthetic strategies (waste production and management, remediation costs). In contrast, switchable solvents change physical properties abruptly upon application of an external stimulus. Piperylene sulfone is one example and can provide a recyclable alternative for dipolar, aprotic solvents such as dimethylsulfoxide (DMSO). Solvents can accomplish more than heat and mass transfer; they can actively contribute to facilitate reaction and product separation while minimizing waste generation and energy consumption.

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“…The special properties of supercritical fluid (SCF) solvents [7,8] for PTC reactions bring substantial environmental and economic advantages. First, they permit the use of totally benign solvents, especially C02, and the solvent separation from product becomes quite facile.…”

Section: Introductionmentioning

confidence: 99%