Green Chemistry & the Role of Academia

Dr. Kamalika Banerjee (Kar)Mahishadal Raj College

“ Chemistry has an important role to play in achieving a sustainable

civilization on earth.”

— Dr. Terry Collins, Professor of ChemistryCarnegie Mellon University

WHAT IS A SUSTAINABLE CIVILIZATION?

WE SHOULD CONSIDER THIS QUESTION FROM

SEVERAL VIEWPOINTS:

• The environment and human health.• A stable economy that uses energy and

resources efficiently.• Social and political systems

that lead to a just society.

IN A SUSTAINABLE CIVILIZATION…

• Technologies used for production of needed goods are not harmful to the environment or to human health.

• Renewable resources (such as plant-based substances or solar energy) are used rather than those, like fossil fuels, that will eventually run out.

IN A SUSTAINABLE CIVILIZATION…

• At the end of their use, materials are recycled if they are not biodegradable (easily broken down into harmless substances in the environment).

IN A SUSTAINABLE CIVILIZATION…

• Manufacturing processes are either designed so as not to produce waste products,

– OR –• Waste products are recycled or

biodegradable.

BUT HOW CAN CHEMISTRY HELP US

TO ACHIEVE A SUSTAINABLE CIVILIZATION?

THE POLLUTION PREVENTION ACT OF 1990

• This was the U.S. environmental law stating that the first choice for preventing pollution is to design industrial processes that do not lead to waste production.

• This is the approach of green chemistry.

GREEN CHEMISTRY WORKS TOWARD

SUSTAINABILITY BY:

• Making chemical products that do not harm either our health or the environment,

• Using industrial processes that reduce or eliminate hazardous chemicals

GREEN CHEMISTRY WORKS TOWARD

SUSTAINABILITY BY:

• Designing more efficient processes that minimize the production of waste materials.

GREEN CHEMISTRY MEANS…

• Preventing pollution before it happens rather than cleaning up the mess later.

GREEN CHEMISTRY MEANS…

• Saving companies money by using less energy and fewer/safer chemicals, thus reducing the costs of pollution control and waste disposal.

EXAMPLES OF GREEN CHEMISTRY

• Reducing lead pollution• Putting out fires the green

way• Safer dry cleaning

LEAD POLLUTION HAS BEEN DECREASED BY…

• Replacing lead in paint with safe alternatives, and

• Replacing tetraethyl lead with less toxic additives (e.g., “lead-free” gasoline).

CHEMICAL FOAMS TO FIGHT FIRES

• Millions of tons of chemical fire-fighting foams used worldwide have discharged toxic substances into the environment, contaminating water supplies and depleting the ozone layer.

PUTTING OUT FIRES THE GREEN WAY

• A new foam called Pyrocool FEF has now been invented to put out fires effectively without producing the toxic substances found in other fire-fighting materials.

CHEMICALS FOR DRY CLEANING

• Perchloroethylene (“perc”) is the solvent most widely used in dry cleaning clothing.

• Perc is suspected of causing cancer and its disposal can contaminate ground water.

A SAFER METHOD OF DRY CLEANING

• Liquid CO2 can be used as a safer solvent if a wetting agent is used with it to dissolve grease.

• This method is now being used commercially by some dry cleaners.

IN SUMMARY,GREEN CHEMISTRY IS…

• Scientifically sound,• Cost effective, and• Leads toward a sustainable

civilization.

The research applications and the anticipated directions for the principles of green chemistry include: a) Clean synthesis (e.g. new routes to important chemical intermediates).

b) Enhanced atom utilization

c) Replacement of stoichiometric reagents (e.g. catalytic oxidation using air as the only consumable source of oxygen).

d) New solvents and reaction media (e.g. use of super-critical fluids and reactions in ionic liquids).

e) Water-based processes and products (e.g. organic reactions in high-temperature water).

f) Replacement for hazardous reagents (e.g. the use of solid acids as replacement for traditional corrosive acids).

g) Novel separation techniques

h) i) Alternative feedstocks (e.g. the use plant-derived products as raw materials for the chemical industry).

ii) New safer chemicals and materials (e.g. new natural product-derived pesticides and insecticides).

iii) Waste minimization and reduction (e.g. applying the principles of atom utilization and the use of selective catalysts).

The potentially detrimental effects of organic solvents on the environment, has led to a rapid growth in research into alternative reaction media. To date, many of the critical fluid processes have utilized supercritical CO2, due to its low cost, attractive critical constants and relative inertness.

The microwave mediated-organic reactions take place more rapidly, safely,and in an environmentally friendly manner, with high yields. Very little solvent and even the use of water as a solvent is a big advantage of microwave chemistry.

Articles from Green Chemistry

PC recycling

Inception of green chemistry in USA

Several awards have been given to processes achieving green chemistry:

(a) For ‘catalytic dehydrogenation of diethanolamine’ : a new technique allowed the production of a herbicide in a less dangerous way. (Avoids cyanide & formaldehyde, is safer to operate, produces high overall yield, fewer process steps.

(b) For developing a new method of synthesizing ibuprofen in 99% yield, avoiding the usage of large quantities of solvents and wastes.

(c) For developing processes using CO2 as the blowing agent, for manufacture of polystyrene foam sheet packaging material. (Allowed elimination of 3.5 million pounds of CFC per year)

(d) For designing a safer marine antifouling compound, ‘Sea-nine’ (degrades far more rapidly than organotins which persist in the marine environment & cause pollution problems).

(e) An award was given for developing a series of activators effective with the natural oxidant hydrogen peroxide. An environmentally benign oxidation technique with widespread applications in the pulp and paper industry and the laundry field, was developed as a result of this work.

(f) Synthesis of an anticonvulsant drug, whereby roughly 34,000 l of solvent and 300 kg of chromium waste were eliminated per 100 kg of the drug produced.

Green chemistry in India

The green chemistry wave has reached our country too.The Indian chapter will promote green chemistry through education, information collection and dissemination,research and international collaboration via conferences, workshops, meetings and symposia. As one of the initial activities of the chapter, the Chemistry Department of University of Delhi has organized an IUPAC Symposium on Green Chemistry in January 2001.

Examples from India

Case 1: Development of solid support reagents

and catalysts useful for organic transformations:

‘Clayan’ Mg–Al–O–Bu t -hydrotalcite ,

montmorillonites , and a layered double

hydroxide fluoride–solid base catalyst for

C–C bond formation provide a few

examples of the solid support reagents that

have been developed at IICT,Hyderabad .

Case 2: The bromoorganics, particularly bromoaromatics, are generally prepared involving toxic chemicals, for instance Br2, which has been a cause of great concern globally.Indeed, it has been possible to develop newer and ecofriendly bromination protocols and brominating agents. In a rather recent endeavour, an experiment has been developed to demonstrate 100% atom economy in the synthesis of pyridinium fluorochromate (PFC).

Case 3: Realizing the toxic effect of many volatile organic solvents (chlorinated hydrocarbons), a research group at IACS, Kolkata initiated a programme to develop green synthetic methods by designing reaction protocols without involving organic solvents. Noticeable success has been achieved by this group of workers by carrying out several useful transformations under the following ‘safer’ conditions: (a) Reactions on solid surface of benign solid inorganic support without solvent(b) Reactions in aqueous media; (c) Reactions in ionic solvents, and (d) Reactions in neat without solvent.

Case 4: Also noteworthy are Kidwai’s dry media reactions used for the preparation of heterocycles, as a step towards Green chemistry.

The Role of the Academia

is to teach the value of Green chemistry to tomorrow’s chemists. Green chemistry education material must be prepared for different levels of education in our country, the topics relevant to a level must be incorporated in the curriculum and implemented appropriately. The lessons in words and examples in writing should be backed up by hands-on experiments. The EPA–ACS Green chemistry Educational Materials Development Project might serve as a reference. However, the material required in the ‘Indian’ context should be designed to suit the targeted audience. An interdisciplinary Science and Technology course on Green chemistry may be included at the graduate level for both science and engineering students.At the level of research, Green chemistry and the related projects may be especially encouraged and appropriately funded.

Courtesy:

1. www.epa. gov

2. Current Science vol 82 No.12, 25 June 2002

3. Science 5 January 2001:vol. 291. no. 5501, pp. 48 - 49

4. Green Chemistry

5. Real World Cases in Green Chemistry, ACS, Washington DC, 2000