Starting molecule

Due to the structure of the symmetrical anhydrobase. every time a 2-methylthiazolium undergoes the attack of a base, theoretically it can result in two trimethine thiazolocyanines the mesomethylsubstituted one and the unsubstituted one. For an unexplained reason, it seems that when position 5 of the starting molecule is substituted, only the mesomethyl dye is produced according to the absorption spectrum, 530 nm for the methylmeso and 569 nm for the 4-phenyl substituted derivative (Scheme 29). ... 

An unusual reaction has been reported by Reynaud et al. (515) in which all the atoms are in the starting molecule. 

At the start, molecules 1 and 2, the two closest to the surface, will enter the mobile phase and begin moving along the column. This will continue while molecules 3 and 4 diffuse to the interface at which time they will enter the mobile phase and start following molecules 1 and 2. All four molecules will continue their journey while molecules 5 and 6 diffuse to the mobile phase/stationary phase interface. By the time molecules 5 and 6 enter the mobile phase, the other four molecules will have been smeared along the column and the original 6 molecules will have suffered dispersion. 

The synthesis of cyclohexenone derivatives by Michael addition followed by intrfflTiolec-ular aldol condensation is called the Robinson annulation, after Sir Robert Robinson, who popularized its use. By annulation we mean the building of a ring onto some starting molecule. (The alternative spelling annelation is also often used.)... 

The optimization job converges quickly, computing an SCF energy of -113.69352 hartrees at the final point. The final structure is close to the starting molecule specification. 

In all these cases, the products have three electrons spinning up and the fourth down (as do the starting molecules). However, formation of, say, two triplets (Ti + ii) or two singlets (ti + Ti). whether ground states or excited, would violate the rule. 

The intermediates may also be obtained in matrices by the reactions of atoms with stable compounds. This process is carried out in two stages -photodecomposition of a starting molecule leading to formation of atoms, and interaction of the atoms with other stable molecules, as, for example, in (2). 

A new scenario has been provided by polymer formation catalysed by mineral surfaces the most important feature here is probably the concentration of the starting molecules at the surface. 

The various evaluations can also be classified into two different types based on the way in which they are invoked. Some are performed only on the starting molecules. For example, this is the case when determining the dissociation energies of the bonds in a molecule. Other evaluations need a knowledge both of the starting materials and the products of a reaction, as in the calculation of heats of reaction (see next... 

One way of stabihzing the initial radical or anion radical is therefore the addition of an acid. Expulsion of a base should produce a similar effect. This is indeed the case (Scheme 2.21), and the secondary radical thus formed is similarly easier to reduce than the starting molecule in most cases. RX is a molecule containing a low-lying orbital able to accommodate the incoming electron, thus leading to the primary radical, RX -, before the nucleophile X- is expelled. We consider here the case of a stepwise process in which the reaction pathway involves the intermediacy of the primary radical rather than a... 

An elementary step can involve the formation of different molecules or ions, or it may involve a change in the energy or geometry of the starting molecules. It cannot be broken down into further, simpler steps. 

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