Communication Boards In Stroke Patients

AWARDS PRESIDENTIAL GREEN CHEMISTRY CHALLENGE

These awards Presidential Green Chemistry Challenge Awards were reported in 1995 by the Administration President Clinton convened the first in 1996. Represent a recognition of outstanding achievements in green chemistry / technology, and are the only awards in chemistry awarded to the presidential level.

atom economy

The concept of atom economy was quantified by Roger Sheldon. The percentage of atoms used is calculated by dividing the molecular weight of the desired product by the molecular weights of all products generated in the reaction. In many reactions, the characteristics of the products discarded are unknown or difficult to determine. Mass conservation to calculate an indicator of economy of atoms that would be the ratio of formula weight of all atoms of the reagents incorporated in the final product (atoms used) on total formula weight of all reagents.

% of atom economy = (FW of atoms utilized / FW of all reactants) x100

The simple observation of some common organic reactions (reorganization, addition, substitution or elimination reactions) reveals that some are inherently more economical than other atoms. If the establishment of a system according to this criterion the reorganization and addition reactions would be at the top followed by the replacement and, finally, would the reaction is atom economy eliminación.La a valuable tool to evaluate the treatment efficiency of inputs, starting materials in a reaction or synthesis, but in order to qualify for a reaction as "green" should consider other dimensions such as:

- Nature of waste product: Is it toxic or harmful to the environment?
- Amount of energy needed to carry out the reaction: The reaction requires excessive amounts of energy?
- Use of auxiliary reagents: synthesis requires solvents or the use of significant quantities of materials to extract or purify the product?
- Percentage yield of the reaction: "The yield is high and most of the waste material pierdecomo?

An example is the synthesis of Ibuprofen

Synthesis of Ibuprofen Boots Company

Ibuprofen is the active ingredient in several brands of commercial products such as Advil, Motrin and Nuprin. Ibuprofen acts as an analgesic (pain relief) and is also effective as nonsteroidal anti-inflammatory drug (NSAID). NSAIDs reduce inflammation caused by arthritis and rheumatism osteroarthritis. When ibuprofen is known as anti-inflammatory drug nonsteroidal and not part of the family of steroids. World production of ibuprofen exceeds 30 million pounds a year. The Boots Company PLC of Nottingham, England was the first to patent the synthesis of ibuprofen in the decade of the 60 (U.S. Patent 3,385,886) and has served as the main method of synthesis for many years.
As always all the atoms of each reagent to be incorporated into the desired end product (ibuprofen) are green, and those ending in unwanted products in brown. Table 10 illustrates the atom economy of the synthesis of the Boots Company and to calculate a percentage of the atom economy of 40%. As noted above, there are approximately 30 million pounds per year of ibuprofen. If the entire world production of ibuprofen was carried out by the Boots process, would generate about 35 million pounds of waste!

% Atom Economy = (FW of atoms utilized / FW of all reactants) X 100 = (206/514.5) x 100 = 40%

Synthesis of Ibuprofen Company BHC

In the years 80 is approved for sale without prescription patent expiring ibuprofen Boots Company. The recognition of the financial opportunities that the production and sale of this drug could offer prompted several companies to embark on the construction of facilities and developing new methods for the preparation of ibuprofen. The Corporation Hoechst Celanese Corporation (Somerville, NJ, now known as Celanese Corporation) discovered a new synthesis of ibuprofen in three steps. Along with the Boots Company founded the BHC Company, to prepare (by the new synthesis) and ibuprofen market. The synthesis of the company BHC is shown in Scheme 4, and later in Table 11 illustrates the atom economy percentage calculation which gives a 77%, with a significant improvement over that obtained by the Boots Company process 40%.

% Atom Economy = (FW of atoms utilized / FW of all reactants) X 100 = (206/266) X 100 = 77%

The atom economy of the BHC Company process can reach a value> 99% if we consider that the acetic acid generated in Step 1 is recovered and used.

The BHC Company process provides not only a significant improvement in the economy of the atom but also other environmental benefits. In These include a three-step catalyzed process to the process of six steps of the Boots Company, which requires auxiliary reagents in stoichiometric amounts. For example, the first step of each process gives rise to the same product (3) from the same reagents (1 and 2). However, the Boots Company process aluminum trichloride used in stoichiometric amounts (which were not considered in Table 10), while the BHC Company process, HF used in catalytic amounts, which is recovered and reused repeatedly. Alumninio trichloride produces large amounts of hydrated aluminum trichloride as a residue that is usually to landfill. The nickel and palladium catalysts used in steps 2 and 3 of the BHC Company process are also recovered and reused.
Because the BHC Company process consists of only three steps (as opposed to six steps of the Boots Company) as it has improved atom economy, this translates into a significant reduction of waste produced and increased productivity (more quantity of ibuprofen in less time and with less equipment.) These factors are significant economic benefits for the Company as a result of the fact need less money to treat the waste generated and requiring a smaller outlay to produce the same amount of ibuprofen. Thus, there is not only a benefit to the environment, but the balance of the company is strengthened, reaping a good image to society for having green the process.