Electronic effects in the cyclocondensation of benzil

Electronic effects are important directing forces in the course of chem. reactions. Small differences in these effects can bring about considerable changes in the results of very similar reactions. Thus, although the ambident nucleophiles urea, o-​phenylenediamine and dibenzyl ketone are expected to take comparable double condensation pathway in their resp. reaction with benzil, urea reacts differently by causing benzil-​to-​benzilic acid type rearrangement. This is attributed to the reduced availability of the lone pair of electrons on nitrogen in urea that is needed for assisting the dehydration of the intermediate

Liquid fuels from plants: Can we meet our petroleum needs from plants?

A review with no refs. of plant-​derives liq. fuels such as vegetable or fatty oils, alc. (EtOH)​, and liq. hydrocarbons

Organic synthesis using clay catalysts: Clays for "green chemistry"

A review. An important family of catalysts that has received significant attention is derived from the soil, the most noteworthy ones being clays and zeolites. Clays are solid acidic catalysts which can function as both Bronsted and Lewis acids in their natural and ion-​exchanged form. Some of the org. reactions that have been conducted using clays as catalysts for reducing environmental pollution are described. Chem. modified clays are considered to be potentially the most cost-​effective nanomaterials, and it is estd. that hundreds of millions of dollars worth of clays will be marketed by 2010. The structure and properties of montmorillonite clay are described. The range of reactions that have been successfully conducted on clay catalysts includes addn., elimination, addn.-​elimination, substitution, rearrangement, Diels-​Alder reactions, and oxidn.-​redn

An appreciation of free radical chemistry. Part 4. Free radicals in atmospheric chemistry

The earth is unique in having a blanket of atm., which has helped the evolution and sustenance of life. For a layman, the atm. seems a simple, just some air that we breathe, with clouds and rain at times. But actually what is atm. and what happens within it in chem. terms is unimaginably complex. Even small changes in its compn. can greatly affect the life processes. Though different kinds of chem. reactions take place in the atm., the most dominant ones involve free radicals. A brief discussion on this aspect is presented

An appreciation of free radical chemistry 3. Free radicals in diseases and health

In the last 20-25 years, considerable insight has been gained regarding the pivotal role played by free radicals in controlling and directing biological processes that cause diseases, as well as defend against them to maintain health. The manifestation of several hereditary diseases has been traced to the eventual tissue injury/DNA damage through free radical reactions taking place at various levels in the biological system. A large body of experimental evidence indicates that the chemical transformations that induce cancer, stimulate atherosclerosis, lead to Parkinson's and Alzheimer's diseases, cause ischemia, and impel ageing process are basically free radical in nature. Ironically, free radicals are also part of the body's defence mechanism. If genetic predisposition and the life style favour the former, then health becomes the casualty

Antoine-​Laurent Lavoisier

For a millenium, till the time of Lavoisier, Alchemy was practised. Alchemy was unscientific, but its practitioners developed useful exptl. methodologies, materials and medicines. In the seventeenth century phlogiston' theory was introduced to explain the results of combustion. Lavoisier, through his extraordinary logical capabilities developed systematic exptl. procedures by adopting proper weighing and measuring methods. This brought about radical change in scientific thoughts and ushered in the era of modern chem. Lavoisier was not only a great scientist, but a revolutionary thinker, a social reformer, a good administrator, a helpful and sociable person and an institution builder. Despite these uncommon qualities, the frenzy of the French Revolution consumed his life in a very tragic way

An appreciation of free radical chemistry. Part 5: Free radicals in organic synthesis

A good understanding of the free radical reaction mechanism has led to the realization of unprecedented control over the chemo-​, regio-​, and diastereospecificity. The free radical chem. has transformed from the intractable to the predictable. In certain systems, radical chem. can deliver results that are far superior to those obtained from conventional ionic or organometallic methods. Some of the syntheses involving free radicals are presented

Jacobus Henricus van't Hoff. A short biographical sketch

A biog. for J H van't Hoff, considered as one of the greatest chemists of all time, is presented. He started his career as an org. chemist. He solved the vexing problem of optical isomerism by proposing an asym. tetrahedral carbon bonded to form different groups. He extended this to include geometric isomerism, and to compds. with heteroatoms in place of asym. carbon. Thus he established the 'chem. in space' or stereochem. He moved on to work on reaction kinetics, equil., thermodn. properties of dil. solns. and related areas. He laid the foundation for phys. chem. through these discoveries and was awarded the first Nobel Prize in Chem. in 1901. Van't Hoff died of tuberculosis at a relatively early age of 59

An appreciation of free radical chemistry 6. Experiments involving free radicals

In the previous five parts, we have seen how the ubiquitous free radicals touch our lives in many ways. In this part, four expts. involving free radical intermediates are described. They are very simple, economical and practical, and can be easily carried out in labs. with meagre resources. They can, therefore, be adapted for MSc chem. practicals as part of free radical chem. course