chemistry Syllabus Stereo and regiochemistry of organic compounds conformers Pericyclic by ashu468

VIEWS: 111 PAGES: 45

									Syllabus:

Stereo and regiochemistry of organic compounds, conformers.

Pericyclic reactions

Organic photochemistry

Bioorganic chemistry: amino acids, peptides, proteins, enzymes
Carbohydrates, nucleic acids and lipids.

Macromolecules (polymers)

Modern techniques in structural elucidation of compounds (Uv-vis, IR,
NMR)

Solid phase synthesis and combinatorial chemistry

Green chemistry
Exam and Marks distributions




  Examinations                 % of Weitage   Date / day     Time

  Quiz 1.                      5%             08-Sept-2010   8-8.50 A.M
                                              Wednesday



  Quiz 2.                      5%             03-Nov-2010    8-8.50 A.M
                                              Wednesday



  Mid sem examination          30%            23-Sep-2010    2-4 PM
                                              Thursday



  End sem examination.         60%            25-Nov-2010    1-4 PM
                                              Thursday
            GREEN




Green Zone             Green Day
Green Tea              Green Marketing
Green Revolution       Green Land
Green Peace            Green Pages
Green Politics         Green Hotels
Green Nanotechnology   Green Computing
An organisation working with small and marginal farmers towards
agro biodiversity conservation and promotion of sustainable
agriculture in dryland south
Indian Green building council:
A green building is one which uses less water, optimises energy
efficiency, conserves natural resources, generates less waste and
provides healthier spaces

                      Green GUIDE/ Green leaving

 •   Buying a fuel-efficient car
                                      •   Researching your vote
 •   Commuting                        •   Saving energy at home
 •   Finding a green job              •   Saving gas
 •   Gardening                        •   Saving money
 •   Recycling                        •   Saving water at home
 •   Recycling electronics            •   Reusing stuff
 •   Researching global warming basics•   Stopping junk mail
Chemistry has the privilege of being
singularly responsible for the tremendous
advancements that humankind has made in
different areas. Almost all fields have used
chemistry in some form or the other for its
betterment

However, industrial chemistry is not
always benign, and it is also criticized for
being responsible for a number of
environmental problems. Thus there is
need for sustainable development and
practice of Green chemistry.
Green chemistry, also called sustainable chemistry, is a
chemical philosophy encouraging the design of products
and processes that reduce or eliminate the use and
generation of hazardous substances

Click chemistry is a chemical philosophy introduced by K.
Barry Sharpless in 2001 and describes chemistry tailored to
generate substances quickly and reliably by joining small units
together. This is inspired by the fact that nature also
generates substances by joining small modular units.
In 2005 Ryoji Noyori identified three key developments in
green chemistry: use of supercritical carbon dioxide as
green solvent, aqueous hydrogen peroxide for clean
oxidations and the use of hydrogen in asymmetric synthesis.
Examples of applied green chemistry are supercritical water
oxidation, on water reactions, and dry media reactions.


Bioengineering is also seen as a promising technique for achieving
green chemistry goals. A number of important process chemicals
can be synthesized in engineered organisms, such as shikimate, a
Tamiflu precursor which is fermented by Roche in bacteria.
The Principle
Paul Anastas and John C. Warner developed 12 principles of green
chemistry, which help to explain what the definition means in
practice.

The principles cover such concepts as:

•the design of processes to maximize the amount of raw material that
ends up in the product

•the use of safe, environment-benign substances, including solvents,
whenever possible;

•the design of energy efficient processes;
the best form of waste disposal: not to create it in the first place.
Principle 1:
Prevent waste: Design chemical syntheses to prevent
waste, leaving no waste to treat or clean up.


Many strategies exist in chemical synthesis that go beyond
converting reactant A to reaction product B.
In CASCADE reactions multiple chemical transformations
take place within a single reactant, in multi-component
reactions up to 11 different reactants form a single reaction
product and in a telescopic synthesis one reactant goes
through multiple transformations without isolation of
intermediates.
A cascade reaction or tandem reaction or domino reaction
is a consecutive series of intramolecular organic reactions
which often proceed via highly reactive intermediates.
Cascade reaction

          I




              H
              N       S-M+                 N
                          Cu(I), K2CO3,        SH
                  S                        S
            X              Ligand (L)
        X = Br, I
                                           H
              N           Ar   Ar-I        N
                      S                        S
              S            Cu(I), K2CO3,   S
                            Ligand (L)
Multicomponent reaction
In chemistry, a multi-component reaction (or MCR) is a
chemical reaction where three or more compounds react to
form a single product.




      Biginelli reaction
Principle 2:

Design safer chemicals and products: Design chemical
products to be fully effective, yet have little or no
toxicity.
Chemicals include inorganic substances such as lead, mercury,
asbestos, hydrofluoric acid, and chlorine gas, organic
compounds such as methyl alcohol, most medications, and
poisons from living things.

Principle 3:

Design less hazardous chemical syntheses: Design
syntheses to use and generate substances with little or no
toxicity to humans and the environment.
Principle 4:
Use renewable feedstock: Use raw materials and feedstock that are
renewable rather than depleting.
Renewable feedstock are often made from agricultural
products or are the wastes of other processes;
CO2 is renewable feed stock, oils and fats, glycerine.
depleting feedstock are made from fossil fuels (petroleum,
natural gas, or coal) or are mined.
Principle 5:
Use catalysts, not stoichiometric reagents: Minimize waste by using
catalytic reactions. Catalysts are used in small amounts and can
carry out a single reaction many times. They are preferable to
stoichiometric reagents, which are used in excess and work only
once.
Catalytic Turnover number

In enzymology, turnover number (also termed kcat) is defined as the
maximum number of molecules of substrate that an enzyme can
convert to product per catalytic site per unit of time.
For example, carbonic anhydrase has a turnover number of 400,000
to 600,000 s-1, which means that each carbonic anhydrase molecule
can produce up to 600,000 molecules of product (CO2) per second.


In other chemical fields, such as organometallic catalysis, turnover
number (abbreviated TON) is used with a slightly different meaning:
the number of moles of substrate that a mole of catalyst can convert
before becoming inactivated.

An ideal catalyst would have an infinite turnover number in this
sense, because it wouldn't ever be consumed, but in actual practice
one often sees turnover numbers which go from 100 to a million or
more.
The term turnover frequency (abbreviated TOF) is used to refer to
the turnover per unit time, as in enzymology.
Principle 6:
Avoid chemical derivatives: Avoid using blocking or protecting
groups or any temporary modifications if possible. Derivatives
use additional reagents and generate waste.




                        Brevetoxin B
Principle 7:
Maximize atom economy: Design syntheses so that the final
product contains the maximum proportion of the starting
materials. There should be few, if any, wasted atoms.
• Atom economy (atom efficiency) describes the conversion
  efficiency of a chemical process in terms of all atoms involved. In an
  ideal chemical process the amount of starting materials or reactants
  equals the amount of all products generated and no atom is wasted.

• Atom economy can be written as:
• % atom economy =
  Molecular weight of the product/Molecular weight of all
  reactants x 100

• Note that atom economy can be poor even when chemical yield is
  near 100%-
• Alder reaction is an example of a potentially very atom efficient
• Atom economy is just one way to evaluate a chemical process. Other
  criteria can include energy consumption, pollutants released and
  price.
Principle 8:

Use safer solvents and reaction conditions: Avoid using solvents,
separation agents, or other auxiliary chemicals. If these
chemicals are necessary, use innocuous chemicals. If a solvent is
necessary, water is a good medium as well as certain eco-friendly
solvents that do not contribute to smog formation or destroy
the ozone.
        Current approaches to solvent
      replacement in synthetic chemistry
•    No solvent
•    Water
•    Carbon dioxide
•    Ionic liquids
•    Lactate esters
•    Fluorous phase reactions
     All have advantages and disadvantages which
    need to be considered when assessing suitability
                    for replacement
               Ionic liquids (IL’s)
• Typically consist of organic cation (often ammonium
  or phosphonium salt) and inorganic anion
                        •BF4   -
                                           Me
                                                 Me    •Zn2Cl5-
             N
               + N                              N+
                                           Me                 OH
      1. Ethylmethylimidazolium        2.Choline chloride/Zinc chloride
      tetrafluoroborate, [emim][BF4]   ionic liquid


• Usually only consider IL’s which are liquid at room
  temperature
• Great variety of structures possible
• Very low vapour pressure – attractive alternative to
  VOCs.
Principle 9:
Increase energy efficiency: Run chemical reactions at
ambient temperature and pressure whenever possible.



Principle 10:

Design chemicals and products to degrade after use:
Design chemical products to break down to innocuous
substances after use so that they do not accumulate in the
environment.
Principle 11:
Analyze in real time to prevent pollution: Include in-
process real-time monitoring and control during syntheses
to minimize or eliminate the formation of byproducts.


Principle 12:

Minimize the potential for accidents: Design chemicals
and their forms (solid, liquid, or gas) to minimize the
potential for chemical accidents including explosions,
fires, and releases to the environment.
GREEN CHEMISTRY

								
To top