Ultrasound In Chemistry

Mit Ultraschall kann man den Fortgang von Reaktionen verfolgen und Arbeitsschritte in der Analytik beschleunigen. Neben den klassischen Anwendungen in der Extraktion stellt dieser Band auch moderne Einsatzgebiete, unter anderem in der Proteomforschung und Polymertechnik, vor. Spezielle Kapitel widmen sich den erforderlichen Instrumenten wie Ultraschallbädern und -sonden.

The effects of heat and light on chemical reactions have long been known and un derstood. Ultrasound has been known to promote chemical reactions for the past 60 years, but despite this, it did not attract the attention of synthetic chemists until recently. This arose historically from early studies which concentrated almost exclu sively on reactions in aqueous media and was also, in some measure, due to the availability of suitable technology. Since the early 1980s a plethora of literature has appeared of direct interest to synthetic chemists and the field has been developing rapidly. The aim of this book is to bring the background of this fascinating field to the atten tion of a wider audience. It explores the literature to date and attempts to indicate other areas in which ultrasound may be exploited. It also hopes to explode some of the myths surrounding this area which have hitherto been regarded by the synthetic community as a bit of a black art! Existing books and reviews have tended to concentrate on the physics of sonochem istry and to catalogue the instances in which ultrasound has proved useful in tack ling synthetic problems. Our aim has been to stress the relevance of this technique to synthetic chemists and we have included a section which deals with the practical aspects of carrying out these reactions.

Power ultrasound has been used for many years in two specific industrial areas: cleaning and plastic welding. Over the last ten years an increasing interest has been shown in its potential for use over a much wider range of chemistry and processing which has been grouped together under the general title of sonochemistry. Most of these uses depend on the generation of acoustic cavitation in liquid media but this text, while underlining the importance of the physics and mathematics of cavitation, mainly concentrates on applications of the technology. After an introduction to the topic and some historical background to the uses of power ultrasound the general principles of acoustic cavitation are explored including some background physics, bubble dynamics and factors which influence cavitation. The remainder of the book incorporates a series of applications of sonochemistry which illustrate the types of physical and chemical effects of ultrasonically induced cavitation which will interest chemists and engineers alike. Amongst the major topics included are chemical synthesis, environmental protection and remediation of water, sewage and soils, polymer synthesis and processing, electrochemistry including both analytical and synthetic aspects and plating. The final chapter reviews the range of ultrasonic equipment available in the laboratory and the progress made towards the scale-up of sonochemistry. The level is introductory to semi-advanced and no topic has been taken to a particularly specialist level since it is intended that this should be of general interest to readers with a scientific background.

This book provides informative, useful, and stimulating reading on the topic of organic sonochemistry – the core of ultrasound-based applications. Given the increasing interest in new and improved technologies, allied to their green and sustainable character (not always a valid premise), there is a great attraction for organic chemists to apply these protocols in synthesis and process chemistry. Unfortunately, as with other enabling technologies, many researchers new to the field have received a simple and dishonest message: just switch on! Therefore a significant portion of sonochemical syntheses lack reproducibility (surprisingly cavitation control and/or ultrasonic parameters are omitted) and the actual role of sonication remains uncertain. While this book does not provide a detailed description of fundamentals, the introductory remarks highlight the importance of cavitational effects and their experimental control. It presents a number of concepts of sonochemical reactivity and empirical rules with pertinent examples, often from classical and recent literature. It then focuses on scenarios of current interest where organic chemistry, and synthesis in particular, may benefit from sonication in terms of both chemical and mechanical activation. The “sustainable corner” of this field is largely exemplified through concepts like atom economy, renewable sources, wasteless syntheses, and benign solvents as reaction media. This book is useful for both researchers and graduate students, especially those familiar with the field of sonochemistry and applications of ultrasound in general. However, it is also of interest to a broader audience as it discusses the fundamentals, techniques, and experimental skills necessary for scientists wishing to initiate the use of ultrasound in their domain of expertise.

As a new and rapidly growing science, the applications of ultrasound methods in environmental technology hold a promising future. Compared to conventional methods, ultrasonication can bring several benefits such as being environmentally friendly (no toxic chemical are used or produced), low cost, and compact, allowing on-site treatment. Besides an overview featuring the background behind ultrasonic technology, this brief summarizes the main studies and innovations reported in recent research that has utilized ultrasound methods in environmental analysis, water, and sludge treatment, soil and sediment remediation to air purification.

The uses of ultrasound in chemistry are examined from a laboratory-oriented viewpoint in this text. The author analyzes the types of ultrasonic equipment available and describes the correct assembly of laboratory apparatus for particular tasks.

Ultrasonic irradiation and the associated sonochemical and sonophysical effects are complementary techniques for driving more efficient chemical reactions and yields. Sonochemistry-the chemical effects and applications of ultrasonic waves-and sustainable (green) chemistry both aim to use less hazardous chemicals and solvents, reduce energy consumpt

Activation Methods examines recent improvements in the utilization of ultrasonic waves and pressurized gases to generate reactions. A straightforward method to use, sonochemistry allows chemical reactions to be carried out under ultrasound without the need for external heat, reagents or catalysts – leading to high yields and the production of a minimum amount of waste. This book presents an overview of the main applications of sonochemistry in green organic chemistry, with an emphasis on texts published within the last few years. High-pressure chemical reactions offer innovative solutions to problems relating to synthesis. They allow access to new products and a further understanding of reaction mechanisms. This book presents the characteristics of hyperbaric activation, which allow the integration of an arsenal of tools for green chemistry, such as the lowering of energy costs and of by-products, as well as the possibility of using substrates that are sterically congested and generally inert.