Barry reaction

A variety of Lewis acids can be used. The Barry Reaction ... 

By polymerising styrene in solution many problems associated with heat transfer and the physical movement of viscous masses are reduced, these advantages being offset by problems of solvent recovery and the possibility of chain transfer reactions. In 1955 Distrene Ltd started a plant at Barry in South Wales for the production of styrene by such a solution polymerisation process and some details have been made available. The essential details of this process are indicated by Figure 16.7. 

A different approach to making chiral drugs is asymmetric synthesis. An optically inactive precursor is converted to the drug by a reaction that uses a special catalyst, usually an enzyme (Chapter 11). If all goes well, the product is a single enantiomer with the desired physiological effect In 2001, William S. Knowles, Ryogi Noyori, and K. Barry Sharpless won the Nobel Prize in chemistry for work in this area. 

Figure 5.15 More detail than seen in Fig. 5.14 is obtained in a scanning electron image. The reacted glass particles are covered by a distinct reaction layer of silica gel (Barry, Clinton Wilson, 1979).

I. Noyori, R. Ohta, M. Hsiao, Y. Kitamura, Ma. Ohta, T. Takaya, H. J. Am. Chem. Soc. 1986, 108, 7117. Ryoji Noyori (Japan, 1938—) and Herbert William S. Knowles (USA, 1917—) shared half of the Nobel Prize in Chemistry in 2001 for their work on chirally catalyzed hydrogenation reactions. K. Barry Sharpless (USA, 1941—) shared the other half for his work on chirally catalyzed oxidation reactions. 

Excerpt 4F is taken from an article written by Demko and Sharpless. (Barry Sharpless was a co-recipient of the Nobel Prize in Chemistry in 2001 for his work on chirally catalyzed oxidation reactions.) In this article, the authors propose a way to synthesize aromatic tetrazoles from nitriles in water, using only sodium azide and a zinc salt. Water, despite its obvious advantages (i.e., safe and inexpensive), rarely succeeds as a solvent in organic synthesis. Thus, a synthesis that uses water successfully is an important scientific accomplishment. 

K. Barry Sharpless United States chirally catalyzed oxidation reactions... 

An unusual phenomenon was reported in the Arctic in the mid-1980s. Ozone measured at ground level was observed to decrease rapidly to small concentrations, at times near zero (Bottenheim et al., 1986 Oltmans and Komhyr, 1986). As seen in Fig. 6.37, an increase in bromide ion collected on filters (f-Br) was inversely correlated with the 03 decrease (Barrie et al., 1988 Oltmans et al., 1989 Sturges et al., 1993 Lehrer et al., 1997) this could reflect either particle bromide or a sticky gas such as HBr that could be collected on the filter simultaneously. This correlation suggested that the loss of ozone was due to gas-phase chain reactions... 

However, what remains unknown is the source of the original bromine that initiates the chemistry. There have been a number of hypotheses, including the photolysis of bromoform which is generated by biological processes in the ocean (Barrie et al., 1988) or reactions of sea salt, either suspended in the air or deposited on, or associated with, the snowpack. These include photolysis of BrN02 formed from the reaction of sea salt particles with N2Os (Finlayson-Pitts et al., 1990), the... 

Arctic at polar sunrise. The mechanism likely involves regeneration of photochemically active bromine via heterogeneous reactions on aerosol particles, the snow-pack, and/or frozen seawater. The source of the bromine is likely sea salt, but the nature of the reactions initiating this ozone loss remains to be identified. For a review, see the volume edited by Niki and Becker (1993) and an issue of Tellus (Barrie and Platt, 1997). 

Barrie, L. A., J. W. Bottenheim, R. C. Schnell, P. J. Crutzen, and R. A. Rasmussen, Ozone Destruction and Photochemical Reactions at Polar Sunrise in the Lower Arctic Atmosphere, Nature, 334, 138-141 (1988). 

However, with the recent recognition of the potential importance of atomic chlorine and bromine under certain conditions in the Arctic at polar sunrise (e.g., see Barrie et al., 1988 and Niki and Becker, 1993), the potential for BrO and CIO chemistry has been reconsidered. As described in Chapter 6 J.4, at polar sunrise there is a rapid loss of ground-level 03 that appears to be associated with reaction with atomic bromine and at the same time, there is evidence that chlorine atoms are playing a major role in the organic removal (Jobson et al., 1994). This is consistent with reactions of sea salt particles generating atomic bromine and chlorine, although the exact nature of the reactions and halogen atom precursors remains unknown. 

Barry, T. I. Glasser, F. P. 2000. Calculation of Portland Cement clinkering reactions. Advances in Cement Research, 12, 19-28. 

Variational transition-state theory has been formulated on various levels [5, 23-27]. At first, there is the group of canonical VTST (CVTST) treatments, which correspond to the search for a maximum of the free energy AG(r) along the reaction path r [23, 24]. It was noticed early that for barri-erless potentials this approach leads to an overestimate of the rate constant because, in the language of SACM, channels are included that are closed. Therefore, an improved version (ICVTST) was proposed [25] that truncates Q at the position r of the minimum of (t(r) by including only states... 

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, P.J. Crntzen, and R.A. Rasmussen (1988) Ozone destruction and photochemical reactions at polar sunrise in the lower Arctic atmosphere, Nature, 334, 138. 

Shoko Yamazaki was born in Osaka, Japan. She studied chemistry at Osaka University and received her Ph.D. in 1986 under the supervision of Prof. Ichiro Murata. From 1985, she was an assistant lecturer at Nara University of Education. She joined the group of Professor Barry M. Trost as a visiting researcher at Stanford University (USA) in 1987-88. She became an assistant professor at Nara University of Education in 1989 and since 2003, a full professor of Nara University of Education. Her current main research interests are the development of new organic synthetic reactions. 

The concept of atom economy, introduced by Barry Trost in 1991, is similar to that of the. E-factor [12]. Here one considers how many and which atoms of the reactants are incorporated into the products. With these two concepts, we can evaluate chemical reactions to get a quantitative result. 

Having covered the major components of a chemical reaction, with the exception of energy considerations, the last topic is doing an overall evaluation of a process. There are two straightforward parameters that may be calculated for a reaction that give some indication of efficiency. One is the percent yield of the purified product. The second is atom economy, which was developed by Barry Trost (1991) of Stanford University. Atom economy can be used to determine the fraction of the molecular weight of the reactant(s) incorporated into the product(s). Separate atom economies are calculated for each product of a reaction. 

The Nobel Prize in Chemistry 2001 was awarded to three researchers for their pioneering work in the field of asymmetric catalysis. One of them, K. Barry Sharpless, was honored for the epoxidations named after him (Section 3.4.6). The second reason for the award was his development of the asymmetric dihydroxylation (AD Figure 17.21). The Sharpless reactions that were honored with the Nobel Prize have three things in common first, they are oxidations, second, they are catalytic asymmetric syntheses, and third, they owe their high enan-tiocontrol to the additive control of stereoselectivity. In the introductory passages to... 

We now leave asymmetric reductions and move on to two asymmetric oxidations, which are probably the two most important asymmetric reactions known. They are both products of the laboratories of Professor Barry Sharpless. 

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