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Home , Ahmed Zewail, George de Hevesy, Gerhard Ertl, Henry Taube, John Polanyi, John Pople

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From Editorial Desk

Why are we proud to be Kineticists?

R.Sanjeev1, V.Jagannadham*2 1Department of , Mizan-Tepi University, Tepi Campus, () 2Department of Chemistry, Osmania University, Hyderabad-500 007, (INDIA) E-mail: [email protected]

In the recent past for the last four to five years, of . They look down the subject of when we used to attend some departmental confer- chemical kinetics. But as we understood, like math- ences, some scientific meetings and PhD viva-voce ex- ematics which is the mother of science, we can proudly aminations, in the lunch break or in the tea break tim- say that chemical kinetics is the mother of chemical sci- ings some teachers so called modern day whom ence. This is well understood by the following diagram we knew very well and who do the research in by any average or chemistry teacher or by a state chemistry and drug discovery used to talk to us ill freshmen college student. . 6E0 ditorial Desk ChemXpress 2(2), 2013

From the diagram it is very clear that the subject The reaction in question was the inversion of cane of chemical kinetics can not simply keep quite with- sugar. The name originates from a prior study by Biot out peeping and interacting through almost all branches and Persoz who used the polarimeter to study the re- of chemistry including pharmacology. Some of the action. lightning facts give the support to this contention by The of cane sugar which rotates the plane “Nobel Prizes” to several virtue of being awarded polarized light to the right but which rotates it to the left working in Reaction Dynamics or Chemical on the addition of a dilute . It was found chemically Kinetics. The events of Nobel Laureates who were that cane sugar absorbs the elements of water and “Reaction awarded Nobel Prizes for their work in changes into a mixture of two different sugars, one be- ” with their names, pho- Dynamics/Chemical Kinetics ing weakly dextrorotatory and the other strongly tographs and their discoveries are being summarized laevorotatory, hence the resultant is a rotation to the chronologically in the following, at first starting with a left. At the same time these workers observed that the small introduction. process is not completed instantaneously but requires a The processes grouped together by Berzelius were: period of time varying with the and concentra-  The transformation of starch into dextrin and sugar tion of the added acid. Biot who, as a , was by (Kirchhoff, 1811). more readily inclined than all the chemists of his day  The same transformation by malt extract (Kirchhoff, (Wilhelmy too was a physicist) to regard the observed 1814). phenomenon as a systematic transient process, also  The decomposition of peroxide into wa- pointed out the importance of a more thorough investi- ter and gaseous in the presence of platinum, gation of these phenomena. However, only Wilhelmy énard, 1818). manganese dioxide, etc. (Th was sufficiently interested to undertake not only the  The action of finely divided platinum on inflammable necessary experiments, but in particular also the funda- öbereiner, 1823). gas mixtures (Davy, 1817; and D mental task of formulating the concepts. ’s work (1850) in chemical kinetics con-  The formation of ether by the action of sulphuric Wilhelmy acid (Mitscherlich, 1834). cerned the acid-catalyzed conversion of a sucrose so- The factor which Berzelius regarded as being com- lution into a 1:1 mixture of fructose and glucose, a re- mon to all these processes was that the substances which action that he followed with a polarimeter. He wrote a interact to form the product do not do so on their own differential equation to describe the reaction, integrated or spontaneously but only after the addition of a certain it, and used it to interpret his experimental results. ’s rate was propor- substance which is not itself consumed. Wilhelmy found that the reaction Mitscherlich had termed the process which he stud- tional to the concentrations of sucrose and of acid ied is a chemical action by contact; Berzelius intro- present. The ratio of the (cane duced the name catalysis instead, with the active but sugar in this case) converted in a given time to the time unconsumed substance being termed the catalytic sub- required for the process he conceived and defined as a stance or catalyst, and the cause underlying the phe- new concept, the rate of , recog- nomena catalytic force. nizing its appropriate mathematical definition at once to The development of a rational view of the nature of be the differential quotient of the amount of substance catalysis was thus absolutely dependent on the creation with respect to time. of the concept of the rate of a chemical reaction. The Wilhelmy then demonstrated that on the simplest concept was formulated (after an inadequate attempt assumption that the amount of sugar converted under by Berthollet) by the German amateur Wilhelmy the given conditions in each element of time is propor- and by a remarkable chance (or is it the intrinsic logic tional to the amount remaining unchanged, there is a of historical evolution?) the first paper to submit a proper large measure of agreement between the observed concept of the rate of a chemical reaction also consti- changes in rotation and those calculated on the basis of tutes the first quantitative study of a process proceed- this assumption, and thus he discovered the general law ing under catalytic action. for the time dependence of the chemical processes. It ChemXpress 2(2), 2013 Editorial Desk61 has subsequently proved to be the fundamental law of gree hitherto undreamed-of. chemical kinetics. 1902 Ostwald found that methyl acetate proved even more suitable owing to its greater solubility and faster This, the second of Nobel Laure- reaction rate, and so one of his first studies in chemical ates in chemical dynamics, features the dynamics, in 1883, dealt right away with a catalytic pro- work of Svante Arrhenius, who won cess, i.e. the catalytic saponification of this particular the in 1902 for his elec- ester under the action of various acids. trolytic theory of dissociation. Although it was not mentioned specifically in his The Nobel Prize was awarded 15 times, to a total Arrhenius of 24 recipients, for work involving various aspects of Nobel presentation, the well-known ’t Hoff chemical dynamics beginning with Jacobus van Arrhenius equation relating reaction rate constants to in 1901, out of a total of 161 recipients in Chemistry activation energies and temperature is fundamental to which is 18% of the total Nobel Prizes went to the people all subsequent studies of reaction energetics and ca- working on Chemical Dynamics or Chemical Kinetics. talysis, and no modern discussion of chemical dynam- Had the award of Nobel Prizes started a century ics could begin without it. Arrhenius is best remembered before, about a dozen scientists like Berzelius, today by teachers and students of chemistry because énard, Davy, Döbereiner, Mitscherlich, Kirchhoff, Th the definition of acids and bases and also the equation Berthollet, Biot, Persoz and Wilhelmy more would have k = A e-Ea/RT relating reaction rate constants to tempera- been awarded Nobel Prizes in Chemical Kinetics. ture through the activation energy that are both named ’ for him. J.H.van t Hoff 1901 1909 The first Nobel Prize went to a Physical Chemist in1901, who is none The third Nobel Laureates in ’T HOFF for his work other than VAN chemical dynamics, features the work on Chemical Dynamics in recognition of Wilhelm Ostwald, who won the of the extraordinary services he has Nobel Prize in 1909 for his work on catalysis, equilibriums, and reaction ’ rendered by the discovery of the laws ’s name remains asso- van t Hoff rates. Ostwald of chemical dynamics and osmotic Ostwald pressure in . He discovered how to express ciated with the catalytic process used the state of chemical equilibrium in reactions and the to manufacture nitric acid from . electromotive force which a reaction can produce; he 1943 explained how the transition occurs between the vari- ’t Hoff’s investi- The fourth Nobel Prize for re- ous modifications of the elements. van search related directly to chemical dy- gations showed that the law, which has been named namics was awarded to George de after the Italian Avogadro, according to which the num- “for his work on the Hevesy in 1943 ber of gas molecules in a given volume is the same for use of as tracers in the study all gases at the same pressure and temperature, em- ”. of chemical processes braces not only substances in the gaseous phase but Hevesy also those in solution, provided that their pressure, Hinshelwood and known as osmotic pressure, is taken into account in the Semenov 1956 same way as the gas pressure in the case of gases. He proved that gas pressure and osmotic pressure are iden- This is the fifth tical, and thereby that the molecules themselves in the Nobel Prize in che- gaseous phase and in solutions are also identical. As a mical dynamics dur- result of this the concept of the molecule in chemistry ing the 20th century. was found to be definite and universally valid to a de- Hinshelwood Semenov Cyril Hinshelwood . 6E2 ditorial Desk ChemXpress 2(2), 2013 and Nikolay Semenov received the Nobel Prize in 1956 the textbook examples. “for their researches into the mechanism of chemical ” in particular, chain reactions. reactions,

Herschbach Lee Polanyi Dudley Herschbach, Yuan Lee, and Eigen Norrish Porter 1986 Eigen, Norrish, and Porter 1967 The 1986 Nobel Prize was awarded to Dudley The 1967 Nobel Prize for research in chemical dy- Herschbach, Yuan Lee, and John Polanyi for their work namics awarded to receive the Nobel Prize in 1967 extending chemical dynamics to the level of individual “for studies of extremely fast chemical reactions, ef- atoms and molecules, using molecular beam and infra- fected by disturbing the equilibrium by means of very red experiments. ” i.e., temperature jump, pres- short impulses of energy, sure jump, and flash photolysis. Rudolph A.Marcus 1992 Fukui and Hoff- The 1992 Nobel Prize in Chem- mann 1981 istry was awarded to Rudolph A. Marcus for development of a theoreti- The 1981 Nobel cal treatment of transfer re- Prize was awarded actions in chemical systems. He un- to and dertook an experimental research pro- Ronald Hoffmann Marcus “for their theories, gram on both gas phase and solution Fukui Fukui reaction rates, wrote the 1952 RRKM papers, and developed indepen- ” wondered what to do next in theoretical research. He dently, concerning the course of chemical reactions. “fron- felt at the time that it was pointless to continue with Those theories, which have come to be known as ” and the “Woodward-Hoffmann rules” RRKM since few experimental data were available. tier orbital theory Some of their experiments were intended to produce respectively, remain important tools for predicting the more. course of organic reactions and they are frequently taught in courses in mechanistic organic chemistry. G.A.Olah 1994 1983 George A. Olah gave the cations of carbon longer life. The 1983 Nobel Prize was awarded to Henry Taube for his work on the mechanisms of electron trans- fer reactions, especially in metal com- ’s work represents a plexes. Taube Olah watershed in the development of the Taube mechanistic chemistry of inorganic complexes. His studies of those reac- tions is a central feature in courses in mechanistic inor- ganic chemistry, and his description of inner-sphere and outer-sphere electron transfer mechanisms remain as ChemXpress 2(2), 2013 Editorial Desk63

– The cations of the carbon compounds Ahmed H.Zewail 1999 – are common in the organic chemistry. carbocations The 1999 Nobel Prize was “for his They occur as extremely reactive and short-lived inter- awarded to mediates in chemical reactions. By giving them longer studies of the transition states of lives George A. Olah has made it possible to observe chemical reactions using femto second ” His pioneering inves- them directly. . tigation of fundamental chemical reac- Zewail tions using ultra-short flashes allowed chemists, for the first time, to monitor reactions on the time scale on which the atoms are actually moving as bonds are broken and formed. The fundamental limit of femto second resolution represents the culmination of a century of progress in chemical dynamics that began ’t Crutzen Rowland Molina with the first Nobel Prize awarded to Jacobus van Hoff in 1901. Paul Crutzen, Sherwood Rowland and 1995 The 1995 Nobel Prize was awarded to Paul “for Crutzen, Sherwood Rowland, and Mario Molina their work in , particularly con- ”. cerning the formation and decomposition of ozone Collectively, their work established atmospheric chem- istry as a major focus at the end of the twentieth cen- Knowles Noyori Sharpless tury. The results have drawn attention to significant en- –in particular, the threat posed to the vironmental issues William S.Knowles, Ryoji Noyori and Barry by . Sharpless 2001 Prize for their development of catalytic asymmetric and synthesis. The achievements of these three chemists are 1998 of great importance for academic research, for the de- The 1998 Nobel velopment of new drugs and materials, and are being Prize was awarded used in many industrial syntheses of pharmaceutical “for to Walter Kohn products and other biologically active substances. This his development of is a description and background information about the ’ award-winning discoveries. the density-func- scientists Kohn Pople ” and to tional theory “for his development of computational and John Pople ” They enabled im- R o d e r i c k methods in . MacKinnon 2003 proved energy calculations on molecules and other multi-atom systems. Chemists have taken advantage Through pio- neering discoveries of those developments to perform calculations on sys- concerning the water tems during reactive encounters, thereby obtaining a and channels of better understanding of chemical dynamics and allow- Agre MacKinnon cells. They have ing for predictions regarding the course of chemical opened our eyes to a fantastic family of molecular ma- reactions based on the energies of various possible chines: channels, gates and valves all of which are transition states. needed for the cell to function. The liquid pressure in . 6E4 ditorial Desk ChemXpress 2(2), 2013 and animal cells is maintained through osmosis. From the table it is very clear that out of 41 Nobel The osmotic pressure thus arising is the reason why Prizes in 29 went to the field of Re- cells are often swollen and stiff, in a flower stalk, for action Dynamics/Chemical Kinetics which is 70% and example. it is 25 % out of total Nobel Prizes. So what we mean to say whether one likes a particular subject or not but ’t he can not ignore it. If our face is not beautiful, it doesn mean that we should break the mirror.

Gerhard Ertl 2007 Has succeeded in providing a de- tailed description of how chemical re- actions take place on surfaces and has in this way laid the foundation of modern surface chemistry. He is Ertl awarded the prize for showing how reliable results can be obtained in this area of research. TABLE Field Number awarded Percentage 24 15 …… 34 21 So or Yes we are proud to be kineticists!!! Chemical Biology 15 9 41 25 29 Physical Chemistry Reaction Kinetics 70 and Reaction Dynamics