Numbering fusion positions

If there is a choice between components of the same size containing the same number and kind of heteroatoms, choose as the base component that one with the lower numbers for the heteroatoms before fusion. When a fusion position is occupied by a heteroatom, the names of the component rings to be fused are selected to contain the heteroatom. 

Orf/io-fused and ortho- and pen-fused ring compounds containing hetero atoms are named according to the fusion principle described in Rule A-21 for hydrocarbons. The components are named according to Rules A-21, B-l and B-2. When the name of a component in a fusion name contains locants (numerals or letters) that do not apply also to the numbering of the fused system, these locants are placed in square brackets (as are also the locants for fusion positions required by Rule A-21.5). The base component should be a heterocyclic system. If there is a choice, the base component should be, by order of preference ... 

Numbering the positions of a tricyclic compound always starts at an atom of an outer ring component that is next to a ring fusion and proceeds around that ring. The starting position is chosen that gives the heteroatoms the lowest possible numbers, as shown for benzo[c]quinoline. If the numbering had started at the position marked as 10 on this stmcture, N would have been position 6, not 5. 

Clicking CH and C fragments into fused hexagons requires an even number of C fragments, which occupy the ring fusion positions. The HC fragments will occupy the rest of the positions. The so-constructed molecules are drawn below ... 

According to a recent rule revision the numbering of each interior atom is now related to its lowest numbered peripheral neighbour atom by a superscript denoting the number of bonds between the two atoms. The following example stands among others for the intricacies involved in the application of orientation rules a) through e). Here the decision for the correct orientation is only possible after lowest locants for the fusion positions have been evaluated. 

It should be noted once again that hetero atoms in fusion positions are numbered sequentially by plain numbers and taken into account in the names of both components to be fused together. 

For designating the position of fusion, the peripheral bonds of the base component, starting with the 1,2-bond, are consecutively assigned italic letters in alphabetical order, following the direction of numbering thus in quinoxaline (35) the 1,2-bond is assigned... 

Fluoran (1) is the commonly used name for the spiro [isobenzofuran- 1,9 -xanthen]-3-one. Benzo[a]fluoran (2) has the benzene ring fused to the 1-and 2-positions of the xanthene moiety. Fusion at the 3- and 4-positions gives benzo[c]fluoran (3). Numbering of the atoms is employed as shown in 1-3. 

One would expect the enthalpy of sublimation (d) to be the largest of the four quantities cited. Molar heat capacities are quite small, on the order of fractions of a kilojoule per mole-degree. (Remember that specific heats have values of joules per gram-degree.) All of the heats of transition (or latent heats) are positive numbers and on the order of kilojoules per mole. Since the heat of sublimation is the sum of the heat of fusion and the heat of vaporization, AHsubl must be the largest of the three. 

Figure 2. Chromosomal translocations leading the production of a MYST HAT fusion protein and cancer, (a) structure of different MYST HAT fusion proteins leading to cancer. Numbers indicate amino acid positions at break points, (b) Model for die consequences of EPCl-PCL fusion on chromatin function...

The key point in this respect is the large number of neutrons produced in the central region. Insofar as these nucleons carry no elechic charge, they mix easily with the previously produced nuclear isotopes, including iron. They do not suffer the electrical barrier that so frustrates the fusion of nuclei, and ever more so as they occupy higher positions in the hierarchy. Neufron capture serves to enrich the range of nuclei that can be engendered by supernova activity. 

For the synthesis of materials, the reactants are placed in the copper crucible. An arc is struck by allowing the cathode to touch the anode. The current is raised slowly while the cathode is simultaneously withdrawn so as to maintain the arc. The arc is then positioned so that it bathes the sample in the crucible. The current is increased until the reactants melt When the arc is turned off, the product solidifies in the form of a button. Because of the enormous temperature gradient between the melt and the water-cooled crucible, a thin solid layer of the sample usually separates the melt from the copper hearth in this sense, the sample forms its own crucible and hence contamination with copper does not take place. Contamination of the sample by tungsten vaporizing from the cathode can be avoided by using water-cooled cathodes. The arc method has been successfully used for the synthesis of various oxides of Ti, V and Nb. A number of lower-valence rare-earth oxides, LnO, 5 have been prepared by arc fusion of LnjOj... 

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