Hot compressed water (HCW, here water above 200 °C) possesses very interesting properties This series of articles gives an overview of the state of the art as regards the understanding of reactions in HCW In the first part the macroscopic and microscopic properties of HCW will be described, followed by a summary of synthesis reactions published The impact of the unique properties shall be discussed in part II, with the thermal degradation of tert-butylbenzene and the oxidation of methanol being used as examples The studies reported will show that the microscopic properties are of more importance to understanding reactions in HCW than assumed in the past

Hot compressed water as reaction medium and reactant properties and synthesis reactions

The hetero Diels-Alder reaction is one of the most important methods for the synthesis of heterocycles. In this article an overview is given for the period since 1989 describing the reaction of heterobutadienes such as oxabutadienes, thiabutadienes, azabutadienes, diaazabutadienes, nitroso-alkenes and nitroalkenes as well as of heterodienophiles such as carbonyls, thiocarbonyls, imines, iminium salts, azo- and nitroso compounds. In addition, several other less common hetero Diels-Alder reactions such as cycloadditions of thiaazabutadienes, oxaazabutadienes, dioxabutadienes, dithiabutadienes, oxathiabutadienes, diazaoxabutadienes as well as the use of N-sulfinyl-phosphaalkynes and other dienophiles are mentioned. A main point of discussion is the stereoselectivity of the reactions and the preparation of enantiopure compounds either using dienes and dienophiles carrying a chiral auxiliary or employing chiral Lewis acids. A point stressed is the synthesis of natural products using hetero Diels-Alder reactions leading to carbohydrates, alkaloids, terpenes, antibiotics, mycotoxins, cytochalasans, antitumor agents and several other classes of natural products.

Hetero diels-alder reactions in organic chemistry

Diels-Alder cycloadditions of 2-pyrones and 2-pyridones

Food pasteurized by hydrostatic high pressure have already been marketed in Japan. There is great interest in this method also in Europe and USA. Temperature and pressure are the essential parameters influencing the state of substances including foods. While the influence of temperature on food has been extensively investigated, effects of pressure, also in combination with temperature, are attracting increasing scientific attention now. Processes and reactions in food governed by Le Chatelier's principle are of special interest; they include chemical reactions of both low- and macromolecular compounds. Theoretical fundamentals and examples of pressure affected reactions are presented.

Pasteurization of food by hydrostatic high pressure: chemical aspects

Diels–Alder Reactions of 1-Azadienes

The recommendation is developed that all synthetic chemists should always consider pressure as one of the routine variables available to them, along with temperature, solvent, reaction time, catalysts, and so forth. Ideally, equipment should be available both in the 1–5 and 10–20 kbar range, the former for the habitual testing of all reaction steps under increased pressure, and the latter for the more unusual instances in which gigapascal pressures appear to force otherwise reluctant reactions. The hope is that synthetic chemists will learn to optimize yields and conversions with respect to pressure as well as the other variables, and to report the pressure used just as routinely as they report reaction times and temperatures now.

清水猛

Papers

Organic synthesis at high pressure

清水 猛

Papers

Organic synthesis at high pressure

清水猛