Nowadays, chemistry is developing very rapidly. In the 20th century, more than 22.85 million compounds were discovered and synthesized, 4 1 times more than the total number of all compounds previously discovered. However, "chemists are too modest", and the brilliant achievements of chemistry in the 20th century have not been recognized by the society. 1 Challenges facing chemistry 1. 1 The image of chemistry is being buried by the great success of its interdisciplinary subjects. Chemistry is a central science, which is closely related to eight sunrise sciences such as life and materials, and has produced many important interdisciplinary subjects. However, the image of chemistry as a central discipline has been buried by the great achievements of its interdisciplinary subjects. Chemistry is an important central science, but it has not been paid attention to. Instead, it is regarded as a bridesmaid science by the society. 1.2 chemistry is being troubled by various environmental pollution problems. While the development of chemistry constantly promotes human progress, it objectively makes environmental pollution possible, but it is human factors that play a decisive role, and ultimately it depends on human understanding to solve this problem. Some famous environmental events are mostly related to chemistry, such as ozone hole, white pollution, acid rain and water eutrophication. On the other hand, it is obviously unfair to attribute all environmental problems to chemical reasons, such as the sharp decline of forests, sandstorms and coal burning. Of course, this is related to the fact that chemistry has not established its own brand. In the earliest chemical process, the treatment of waste gas and waste residue was not considered at all, so many chemical processes will bring environmental pollution. Now, some people regard chemistry and chemical industry as pollution sources. People began to hate chemistry, and then they had an inexplicable fear of chemistry. As a result, all foods containing "artificial additives" are unpopular, and some cosmetic manufacturers have repeatedly stressed that this product does not contain any "chemicals". In fact, these are all prejudices against chemistry, but it is chemists who monitor, analyze and manage the environment. Green chemistry is an inevitable science to meet the challenge. We should not only know and transform the world, but also protect it. So is chemistry. In order to meet the challenges faced by chemistry, it is urgent to advocate green chemistry. 2. 1 The concept of green chemistry Green chemistry, also known as environment-friendly chemistry, environment-friendly chemistry or clean chemistry, refers to the chemical reaction and process based on the basic principle of "atomic economy", that is, in the chemical reaction to obtain new substances, every raw material atom involved in the reaction is fully utilized and scientific means are adopted to prevent pollution from the beginning, so the process and terminal are zero emissions and zero pollution, which is a kind of chemistry to prevent pollution from the source. Green chemistry is different from environmental protection. Green chemistry does not passively control environmental pollution, but actively prevents chemical pollution, thus fundamentally cutting off pollution sources. Therefore, green chemistry is a higher level of environment-friendly chemistry. 2.2 the emergence and background of green chemistry today, the concept of sustainable development has been widely recognized by the world. It emphasizes the coordinated development of population, economy, society, environment and resources, which means not only developing economy, but also protecting natural resources and environment so that future generations can develop sustainably. Green chemistry is a sustainable development theory based on the harmonious development between man and nature. 1984 "waste minimization" is put forward by the us environmental protection agency, which is the original idea of green chemistry. 1989 The US Environmental Protection Agency put forward the concept of "pollution prevention". 1990, the federal government of the United States passed the Pollution Prevention Action Act, which established pollution prevention as a national policy, and the word "green chemistry" appeared for the first time in the provisions of this law. 1992, the us environmental protection agency issued the pollution prevention strategy. From 65438 to 0995, the US government established the "Presidential Green Chemistry Challenge Award". From 65438 to 0999, the Royal Society of Chemistry founded the first international journal of green chemistry, which marked the official appearance of green chemistry. China is also closely following the forefront of chemical development in the world. 1995, the Department of Chemistry, Chinese Academy of Sciences determined the green chemistry and technical consultation topic for academicians. 2.3 The core content of green chemistry Atomic economy is the core content of green chemistry. This concept was first put forward by Trost, a famous organic chemist from Stanford University in the United States, in 199 1 (for which he won the 1998 "Presidential Green Chemistry Challenge Award"), that is, what percentage of atoms in raw material molecules have been converted into products? The ideal atomic economic reaction is that 100% of atoms in raw material molecules are converted into products, and no by-products or wastes are produced, thus achieving "zero emission" of wastes. He used the atom utilization rate to measure the atom economy of the reaction, and thought that efficient organic synthesis should make maximum use of every atom of the raw material molecule and combine with the target molecule. The atomic economic reaction of green chemistry has two obvious advantages: one is to maximize the use of raw materials, and the other is to minimize the discharge of waste. The expression of atomic utilization ratio is: atomic utilization ratio = (sum of formula amount of expected products/formula amount of reaction substances) × 100%. For example, the preparation of pollution-free oxidant hydrogen peroxide can adopt ethyl anthraquinone method, that is, hydrogen and oxygen can be directly synthesized under the catalysis of 2-ethylanthraquinone and Pd, and 2-ethylanthraquinone can be recycled. The atomic utilization rate of this reaction is 100%, which reflects the atomic economy, reduces the generation and discharge of waste, and is a typical zero emission.