Introduction to Green Chemistry

John Andraos, Albert S. Matlack

• Publisher: CRC Press
• Year: 2022
• eBook ISBN: 9781000542363
• Topic: Physical Sciences
• Subtopic: Environmental Science

Interest in green chemistry and clean processes has grown so much in recent years that topics such as fluorous biphasic catalysis, metal organic frameworks, and process intensification, which were barely mentioned in the First Edition, have become major areas of research. In addition, government funding has ramped up the development of fuel cells and biofuels. This reflects the evolving focus from pollution remediation to pollution prevention.

Copiously illustrated with more than 800 figures, the Third Edition provides an update from the frontiers of the field. It features supplementary exercises at the end of each chapter relevant to the chemical examples introduced in each chapter. Particular attention is paid to a new concluding chapter on the use of green metrics as an objective tool to demonstrate proof of synthesis plan efficiency and to identify where further improvements can be made through fully worked examples relevant to the chemical industry.

NEW AND EXPANDED RESEARCH TOPICS

• Metal-organic frameworks
• Metrics
• Solid acids for alkylation of isobutene by butanes
• Carbon molecular sieves
• Mixed micro- and mesoporous solids
• Organocatalysis
• Process intensification and gas phase enzymatic reactions
• Hydrogen storage for fuel cells
• Reactive distillation
• Catalysts in action on an atomic scale

UPDATED AND EXPANDED CURRENT EVENTS TOPICS

• Industry resistance to inherently safer chemistry
• Nuclear power
• Removal of mercury from vaccines
• Removal of mercury and lead from primary explosives
• Biofuels
• Uses for surplus glycerol
• New hard materials to reduce wear
• Electronic waste
• Smart growth

The book covers traditional green chemistry topics, including catalysis, benign solvents, and alternative feedstocks. It also discusses relevant but less frequently covered topics with chapters such as "Chemistry of Long Wear" and "Population and the Environment." This coverage highlights the importance of chemistry to everyday life and demonstrates the benefits the expanded exploitation of green chemistry can have for society.

1 Introduction

DOI: 10.1201/9781003033615-1

This chapter will consider what is toxic, what is waste, why accidents occur, and how to reduce all of these.¹

1.1 General Background

In the glorious days of the 1950s and 1960s, chemists envisioned chemistry as the solution to a host of society’s needs. Indeed, they created many of the things we use today and take for granted. The discovery of Ziegler–Natta catalysis of stereospecific polymerization alone resulted in major new polymers. The chemical industry grew by leaps and bounds until it employed about 1,027,000 workers in the United States in 1998.² By 2007, this number had dropped to 872,200. Some may remember the DuPont slogan, “Better things for better living through chemistry.” In the Sputnik era, the scientist was a hero. At the same time, doctors aided by new chemistry and antibiotics felt that infectious diseases had been conquered.

Unfortunately, amid the numerous success stories were some adverse outcomes that chemists had not foreseen. It was not realized that highly chlorinated insecticides such as DDT [1,1-bis(4-chloropheny1)-2,2,2-trichloroethane] (Scheme 1.1), also known as dichlorodiphenyl-trichloroethane (made by the reaction of chloral with chlorobenzene), would bioaccumulate in birds. This caused eggshell thinning and nesting failures, resulting in dramatic population declines in species such as peregrine falcon, bald eagle, osprey, and brown pelican. Rachel Carson³ was one of the first to call attention to this problem. Now that these insecticides have been banned in the United States, the species are recovering. Some are still made and used in other countries, but may return to the United States by long-range aerial transport (e.g., from Mexico). (Compounds applied to plants, building surfaces, and such may evaporate and enter the atmosphere where they may remain until returned to the ground at distant points by rain or by cooling of the air.⁴) DDT is still made in Mexico, China, India, and Russia. A global treaty to ban these persistent pollutants is being sought.⁵

SCHEME 1.1 Chemical structure of pesticide 4,4’-dichlorodiphenyl- trichloroethane (DDT).

It was also not appreciated that these compounds and other persistent highly chlorinated compounds, such as polychlorinated biphenyls (PCBs), can act as estrogen mimics.^6,7 Surfactants such as those made from alkylphenols and ethylene oxide are also thought to do this, although perhaps to a lesser extent. The effects are now showing up in populations of native animals, raising questions about possible effects in humans. A program is being set up to screen 86,000 commercial pesticides and chemicals for this property.⁸

Thalidomide (Scheme 1.2) was used to treat nausea in pregnant women from the late 1950s to 1962. It was withdrawn from the market after 8000 children in 46 countries were born with birth defects.⁹

SCHEME 1.2 Chemical structure of teratogenic (S)-thalidomide.

The compound has other uses as a drug as long as it is not given to pregnant women. In Brazil, it is used to treat leprosy. Unfortunately, some doctors there have not taken the warning seriously enough and several dozen deformed births have occurred.¹⁰ The U.S. Food and Drug Administration (FDA) has approved its use for treating painful inflammation ofleprosy.¹¹ It also inhibits human immunodeficiency virus (HIV) and can prevent the weight loss that often accompanies the acquired immunodeficiency syndrome (AIDS). Celgene is using it as a lead compound for an anti-inflammatory drug and is looking for analogues with reduced side effects.¹² The analog below (Scheme 1.3) is 400–500 times as active as thalidomide. Revlimid (Scheme 1.4) is approved for treating multiple myeloma.¹³

SCHEME 1.3 Chemical structure of a thalidomide analog.

SCHEME 1.4 Chemical structure of revlimid.

Chlorofluorocarbons were developed as safer alternatives to sulfur dioxide and ammonia as refrigerants. Their role in the destruction of the ozone layer was not anticipated. Tetraethyl lead was used as an antiknock agent in gasoline until it was learned that it was causing lead poisoning and lowering the intelligence quotient (IQ) in children. We have still not decided what to do with the waste from nuclear power plants, which will remain radioactive for longer than the United States has been in existence. Critics still question the advisability of using the Yucca Mountain, Nevada, site.¹⁴ They say that the finding of ³⁶Cl from atomic bomb tests in the 1940s at the depth of the repository indicates that surface water can get into this site.¹⁵

Doctors did not anticipate the development of drug-resistant malaria and tuberculosis. The emergence of Legionnaire’s disease, Lyme disease, AIDS, Hantavirus, and Ebola virus was not anticipated. Most drug companies are still unwilling to tackle tropical diseases because they fear that poor people afflicted with diseases will not be able to pay for the drugs.¹⁶

Today, there is often public suspicion toward scientists.¹⁷ Some people picture a mad chemist with his stinks and smells. There is a notion among some people “that science is boring, conservative, close-minded, devoid of mystery, and a negative force in society.”¹⁸ Chemophobia has increased. Many people think that chemicals are bad and “all natural” is better, even though a number of them do not know what a chemical is. There is a feeling that scientists should be more responsible for the influence of their work on society. Liability suits have proliferated in the United States. This has caused at least three companies to declare bankruptcy: Johns Manville for asbestos in 1982, A. H. Robins for its “Dalkon Shield” contraceptive device in 1985, and Dow Corning for silicone breast implants in 1995.¹⁹ Doctors used to be respected pillars of their communities. Today they are subjects of malpractice suits, some of which only serve to increase the cost of health care. Medical implant research is threatened by the unwillingness of companies such as DuPont and Dow Corning to sell plastics for the devices to implant companies.²⁰ The chemical companies fear liability suits. Not long ago drug companies became so concerned about lawsuits on childhood vaccines that many were no longer willing to make them. Now that the U.S. Congress has passed legislation limiting the liability, vaccine research is again moving forward. The lawsuits had not stimulated research into vaccines with fewer side effects, but instead had caused companies to leave the market.

1.2 Toxicity of Chemicals in the Environment

The public’s perception of toxicity and risk often differs from that found by scientific testing.²¹ The idea that “natural”²² is better tha...

Table of contents

• Cover
• Half Title Page
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface to the Third Edition
• Preface to the Second Edition
• Preface to the First Edition
• Author
• 1 Introduction
• 2 Doing without Phosgene, Hydrogen Cyanide, and Formaldehyde
• 3 The Chlorine Controversy
• 4 Toxic Heavy Metal Ions
• 5 Solid Catalysts and Reagents for Ease of Workup
• 6 Solid Acids and Bases
• 7 Chemical Separations
• 8 Working without Organic Solvents
• 9 Biocatalysis and Biodiversity
• 10 Stereochemistry
• 11 Agrochemicals
• 12 Materials for a Sustainable Economy
• 13 Chemistry of Long Wear
• 14 Chemistry of Recycling
• 15 Energy and the Environment
• 16 Population and the Environment
• 17 Environmental Economics
• 18 Greening
• 19 Metrics
• Appendix
• Index