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It is necessary to apply chemical science with vision to achieve a better quality and greater environmental security

The environmental quality through chemistry

Ramon Mestres Quadreny. Professor of organic chemistry at the University of Valencia, Department of chemistry; Chairman of the Committee for Green Chemistry of the FECS Division for Chemistry and Environment.01/12/2004

In the following article, the author presents some of the concepts, objectives and fields of attention of chemistry to be developed over the next few years if there is chemistry in the future. It does lack imagination and defeat routines, and academic schemes, as well as industrial inertia. It is an opportunity afforded to the chemist with vision for the future, which perceives the chemistry as a service to humanity.

We can say without fear of exaggeration that modern life and any of the aspects that characterize it, it would be impossible without the knowledge that provides the chemistry as a science and the application which of them makes the industry. It is also clear that the more developed societies have become very sensitive to anything which may affect quality environmental, damaged by various forms of pollution and stricken by incidents that cause serious harm to people or the environment.

Various forms of pollution, as well as the serious incidents that take place in the form of explosions, fires, mass poisoning, have very often origin in chemical substances. A widespread opinion that contemplates the chemistry as a serious threat has been created as well. However, the chemical industry is only partly responsible for this chemical contamination. Just remember that the increase in anthropogenic greenhouse effect is mainly caused by carbon dioxide generated by the automotive industry and the production of energy and methane generated by livestock, while synthetic halogenated compounds contribute to a lesser extent. It is recalled in the same way that serious incidents affecting the safety of persons or to the environment, due in many occasions to chemistry, it is also due to other activities, for example, to the production, transport or storage of fuels.

The social concern about chemistry extends both emissions and risks of the products that it used the chemical industry and the harmful effects that accompany or follow the implementation of the final products from other sectors of production or by the own consumer. Pesticides, organic solvents, plastics, and some drugs can bring to mind guideline examples of harmful effects caused by the final products.

It has created a widespread opinion that contemplates the chemistry as a serious threat

Although the chemistry is not the only source of chemical contamination, its responsibility, to provide effective solutions for the reduction of pollution and to avoid risks, certainly extends to the prevention of the effects it causes herselfthe prevention of due to other sectors and the remediation of pollution already produced, disseminated or not.

The current responsibility of chemistry in relation to environmental quality also extends to the future. Note two unquestionable facts. On the one hand, the extinction of the oil, natural gas and coal, sources with much of the energy used (75 percent) and the basic subjects of the organic chemical industry (8 per cent of the crude oil provides a 98 per cent of the raw materials for the organic industry). On the other hand, the development of the young Nations, lack of adequate and affordable, clean chemical procedures will cause a contamination level dimensionally exceeding the toll far from industrialized nations.

It should also draw attention to the fact that the responsibility of the chemical industry as the direct cause of contamination and risk causes a serious increase in cost. Indeed, the social and legislative forces exercise already now and expected more and more in the future, a legal and fiscal pressure on industries to force the reduction of the emission of polluting substances in the form of gases, aqueous effluent, solid waste. This pressure results in the introduction of mitigation technologies that represent a significant cost of production. The maintenance and the introduction of security measures against the toxic, corrosive, flammable or explosive nature of the substances used or generated is also very costly. Likewise, to pay greater attention to the harmful effects of the final products process of launching a new product or material to the market is much more complex and often reduces the continuity of the production. The extinction of the fossil fuels is also a cause of a progressive cost of production.

With all the above so far it can be said that it is necessary to apply chemical science with vision to achieve a better quality and greater environmental security, facilitate the development of the young Nations and ensure the survival of the own chemistry. This idea responds precisely to what in some countries is known as "green chemistry" and in others as "Sustainable chemistry".

Photography: Bayer

Sustainable chemistry

Is understood here as sustainable chemistry employment and the development of the theoretical foundations and applications of chemistry necessary for maintaining and enhancing the contribution of chemistry to the general welfare of all human beings and the environmentat the present time and in an unlimited period of time.

The novelty of the Green Chemistry lies not so much on trying to get a non-polluting and safe industry, such as wanting to achieve a clean and safe chemical process at its root. Control over the harmful effects and risks of production has been undertaken in the plane defined by the dimensions technique (palliative, additional engineering to the process) and economic (increase in the investment and the cost of production). What we want now is to put the emphasis on the chemical dimension, with changes in the own reaction, to reduce the risks and the need for mitigation techniques. The emphasis in chemistry is not an oversight of the engineering; much of the reduction of the generation of waste depends on the development of new reactors, for example, the intensive production.

The introduction of innovations from the perspective of sustainable chemistry is profitable already now. In fact there are industries and scientific institutes in United States, Australia, Germany, Switzerland and Spain which have departments dedicated to the amendment of the industrial processes for the practice of a chemical clean the same root.

General objectives

In correspondence with the origin of the harmful effects and the risk of chemistry, with concern for the extinction of the sources of raw materials and other causes of pollution and risks, the objectives to be achieved can be expressed as follows:

Reduction of the generation and use of polluting substances in the chemical process.
Reduction in the use of substances with dangerous nature in the chemical process.
Reduction of the harmful effects of the final products.
Reduction of the use of extinguibles sources of raw materials and of scarce resources.
Reduction of pollution already generated.

Chemical production as the origin of pollution

The fundamental principle was enunciated in 1978 by Trevor Kletz: "What you don't have can't leak". Indeed, if unwilling leaks, spills uncontrolled and waste or effluents which contribute to environmental pollution, the most radical form is not to use or produce substances susceptible of these emissions. Where must address for the attention, first of all, is the same chemical process, which are used and there are likely to contribute to the pollution substances.

Preparativas reactions involve some starting substances, some reagents, a few catalysts and a means of reaction, often an organic solvent. A product has been formed at the end of the reaction. But a few secondary products, generated in alternative courses of the reaction are also. Apart from the simple reduction in performance, the existence of more than one substance in the mixture of reaction requires some means of separation and purification of the product (especially important in the pharmaceutical industry), involving the use of solvents and other ancillary products. There is nothing new in organic synthesis search for selective procedures to prevent the generation of secondary products; What is notable now is having in mind that these by-products are generic cause of pollution.

Newest appears, the less the chemical academic, the observation of the formation of the concomitant products, that necessarily accompany product, regardless of the performance, by forming part intrinsic conversion; they are a requirement of the stoichiometry of the reaction. You can see with ease the distinction between secondary and concomitant products in a reaction as simple as the preparation of an alkene from a halide of rent; the terminal alkene is a secondary product, whose formation could perhaps be mitigated by changing the reaction conditions, while the formation of alcohol and alkali halide are inherent to the chosen reaction.

In order to show the magnitude that can reach the concomitant products in the generation of waste, is enough to mention that the balance of material produced in the Friedel Crafts Friedel, one of the steps of the synthesis of ibuprofenIt is 880 grams of waste, without considering the solvents lost per 178 grams of the ketone intermediate. The synthesis of ibuprofen was later improved as regards the production of waste. The new synthesis has been worthy of a "Green Chemistry Presidential Award" at United States.

The chemical industry is responsible for only part of chemical pollution

Split and reactive substances dangerous

A large number of substances used in the chemical industry, or as a result of its activity are cause of risk, even in small quantities, due to its aggressive properties, or toxic. It's substances which in the event of a leak or spill can cause damage significant or serious people who handle them or people, animals or plants in the environment (Bhopal, Seveso). Other unfortunate or tragic events are

associated with flammable or explosive substances (Flixborough, Toulouse). These situations can be granted by the own presence of dangerous substances or by his accidental generation in the process, but the risk of accident must be drastically reduced in any case with the reduction in the use of hazardous substances. There is zero risk, and sooner or later, dangerous substances are the cause of incidents, poisoning, explosions, and the less, in situations of alarm and introduction of expensive security measures.

In some cases can be avoided with a simple change of reactive risk or dangerous solvents by others of danger clearly lower, while on other occasions the complete conversion rate modification will be necessary.

A very simple example of reduction of the danger of a backlash, increases its atomic performance, can be bromination bencílica of a toluene replaced with alkali bromide, oxygenated water and an acid, which prevents the use of brominereactive dangerous, or of the N-bromosuccinimide, that gives a low atomic performance and requires both its preparation and recycling bromine.

Another example, widespread replacement of reactive hazardous is the use of carbonate from methyl instead of phosgene or methyl sulphate. Methyl carbonate can act, subject to conditions, as a acilante agent or agent metilante.

Harmful effects of the final products

The application of certain final products used as a basic subject in medicine, agriculture, construction, in various kinds of industries and in the products and materials in common use, has been accompanied by harmful effects to the health or the environment. The need then find alternative substances, while maintaining or improving the properties that make them suitable for its role, without these disadvantages is apparent.

However, considering the harmful effects of the final products, it is revealed that same production of the compound is already a negative, perhaps minimal, but non-zero environmental impact. It joined then the effects of the own compound in its function, or those of their waste after its application. Is reached then the need for the assessment of the impact of the product throughout the cycle of life (LCA Life Cycle Assessment), whereas from the sources of raw materials to the mineralisation of the waste or recycling, through its production: reagents, solvents, etc. This assessment can be extremely useful in the decision-making on the use of alternative products.

A second part in the final products is aimed at the design of new products, pesticides, detergents, polymers, colorants, without harmful effects. It is necessary to the development of the necessary skills to be able to design that may not be toxic and substances that may be recycled or mineralizadas easily, while maintaining the properties that make them suitable for use.

Photography: Solvay

The current responsibility of chemistry in relation to environmental quality also extends to the future

Extinguibles sources of raw materials

Currently 98 percent of the chemicals industrially produced and used in a way or another as consumer products derived from oil. The forecasts of the extinction of its reserves on the planet are different so it refers to the time. Margins also vary depending on who is included or not coal and natural gas. In any case, all the forecasts have to accept the limited nature of these reservations and the anticipation of a gradual rise in prices. The sustainability of long-term production is possible only if there are renewable raw materials, with short courses of renewal, susceptible of indefinite repetition over time. This points clearly to the plant Kingdom as a source of organic matter.

The use of renewable sources in obtaining raw materials for the chemical is not anything new. The novelty now is to try to obtain from plants or microorganisms which so far has been getting mostly from oil or coal.

In the generation of energy fossil fuel

The reduction of the consumption of fossil fuels is a double interest. On the one hand his character extinguible and on the other hand, the increase in carbon dioxide in the biosphere resulting from combustion.

Point here only some fields in which chemistry can provide solutions to reduce the consumption of fossil fuels. Firstly, the contribution to the availability of alternative renewable sources. Include here the production of bio-diesel from vegetable triglyceride and the construction of efficient solar panels, or the development of thermochemical pumps of solar energy.

Secondly, the contribution of chemistry can be oriented to the increase in efficiency and cleanliness in the generation of energy from fossil fuels, as it can occur in the form of improvements in combustion systemsthe resulting gases purification or in the development of batteries of combustion. A contribution that could be of great importance would be to find ways to use carbon dioxide as a renewable source of carbon.

The responsibility of the chemical industry as the direct cause of contamination and risk causing a serious increase in cost

Pollution already generated

Chemistry also needs to provide procedures to reduce pollution generated, either before or after the emission into the atmosphere. Given the toxicity of the policlorodibenzodioxinas ("dioxin"), are very important studies on the mechanisms of his generation in the thermal treatment of residual organic matter and the implementation of the forms that reduce or prevent this generation, as they were recently targeted by Dieter Lenoir in the "4th Green Chemistry Conference" of Barcelona.

The use of renewable sources in the procurement of raw materials for chemical is nothing new

In the destruction of pollutants in aqueous media, especially in treatment plants, should be simply mentioned procedures photochemical and electrochemical, the use of ozone in the treatment of the waste water or the applications of the catalysts for the activation of the water oxygenated in industries such as the trash or petrochemicals.