Acyclic chain structure

Aliphatic Hydrocarbons. These are acyclic hydrocarbons with an open-chain structure, which can be either straight (i.e., linear) or branched. The former type are called normal (or n-) aliphatic compounds. Unsaturation is manifested in the form of double or triple bonds. 

Coordination studies of acyclic thioether ligands to silver(I) centers has also been studied. Poly(alkylthio)aromatic systems have been used to form supramolecular silver(I) compounds. With the ligand 2,3,5,6-tetrakis(isopropylthio)benzoquinone the compound has a linear chain structure in which silver(I) has a tetrahedral coordination.1156 A similar structure has the compound with the hexakis(methylthio)benzene,1157 but with the hexakis(tolylthio)benzene the silver... 

Fig. 6. Two novel structures observed for Pt(3.0+)2, and an octaplatinum chain structure observed in the acyclic amidate systems.

Conjunctive name a combination of two names, one of which represents a cyclic structure and the other an acyclic chain, with one hydrogen atom removed from each e.g.. benzenemethanol. 

The famous John-Sachs theorem [26] gives the Kekule structure count of a benzenoid in terms of an np x np determinant, where np is the number of peaks [27], equal to the number of valleys [27]. As pointed out by Gutman and Cyvin [28] the elements of this John-Sachs determinant may be identified with K numbers of certain benzenoids, occasionally degenerated to an acyclic chain (polyene), or zero. An application to the oblate rectangles gave the result [2,13] ... 

Cyclolinear carbosilane polymers with disilacyclobutane rings in the main-chain structure were prepared by means of acyclic diene metathesis (ADMET) polymerization of the corresponding l,3-dibutenyl-l,3-disilacyclobutanes in the presence of Grubbs catalyst (Scheme 13) <2003PP789, 2004MM5257, 2004PP118>. 

One of the most fruitful developments in purine chemistry within the last two decades was the discovery that acyclic purine nucleoside derivatives are very potent inhibitors of the proliferation of certain viruses. " In acyclic purine nucleosides, the ribose moiety is replaced by an acyclic chain corresponding to the upper or lower part of the /I-D-ribofuranose ring. The most important acyclic purine nucleosides are shown by the structures of acyclovir (Zovirax, ACV, acyclo G, 1), DHPG (2), DHPA (3), and PMEA (4). 

Such rotaxanes incorporate a macrocyclic structure (representative of a bead) on an acyclic chain (thread), with bulky stopper groups at their ends to prevent dethreading. The position of the bead on the thread, and hence representation of information, is controlled by the incorporation of stations on the thread upon which the bead preferentially resides. Requirements of a successful system are that the bead can be controllably shuttled between stations by an external stimulus and that the position of the bead can be subsequently read out. 

A complete first-order analysis of the quinoxaline tetra-acetate confirms the acyclic structure. Coupling constants (7i 2 3-0, 72 3 8 5, /4 a, 4b 12-0, 73, 4a 3-0, Js 4b 5 5 c./sec.) for the acyclic chain, were obtained that were indicative of a high degree of conformational purity and which were in agreement with an extended planar zig-zag arrangement as the favoured conformation. 

Commercially available dihydro-5-(hydroxymethyl)-4,4-dimethyl-2(3H)-furanone (42) was chosen as the starting material since it incorporated the essential structural features that are present in the acyclic chain of diazene 41. To synthesize both coriolin (3) and hypnophilin (4), enone 39 was selected as a common intermediate. While 39 had previously been converted to coriolin (3), its conversion to hypnophilin (4) had not been accomplished. 

The magnetic moment of I2, uhidi equals 2 Bid., decreased with decreasing temperature, becoming finally zero. Since contains an even number of elections, it is expected to be diamagnetic. Ciyoscopic and conductivity measurements also supported a dimerization process. The structure of 14 is not known, a tetrahedral, square planar or acyclic chain all being reasonable. 

There is also ambiguity concerning the polyphosphorus species formed when (PhP)s is treated with alkali metals in THF solution, but new P n.m.r. data are providing information showing complex dependence on both the metal and the temperature.With potassium, the product is K2(PhP)4, but the data rule out a conventional straight-chain structure and suggest one containing a chelated potassium ion (7). While a similar structure appears to be probable for the disodium compound, the data for Li2(PhP)4 point to an acyclic structure. Similarly, linear structures now seem probable for the M2(PhP)3 species rather than the cyclic dianions considered previously. 

Figure 6.5 Supramolecular association (black-dashed lines) found for acyclic thiocarbamide structures having a Z configuration. Hydrogen atoms not participating in intermolecular interactions are omitted for reasons of clarity, (a) Supramolecular chain mediated by N-H... O (amide) hydrogen bonding in (49), (b) supramolecular chains mediated by N-H... O hydrogen bonding in (50) and (c) supramolecular chains mediated by N-H... N hydrogen bonding in (45)...

The simple glycosylamines are hydrolyzed by dilute acids (5, Pa, 6), and are reduced to 1-amino alcohols (P). Evidence to be presented below indicates that the acyclic and ring forms probably exist in an equilibrated solution hence, the ring and open-chain structures will be used interchangeably in the present discussion. 

The INBS values for the 3000 structure subset were calculated using a shortest-path algorithm similar to that used by Carhart et al,. For each molecule, the number of INBSs of length n are scanned to form a frequency distribution for n=l-20. The frequency of INBS values >20 is also recorded. Thus INBS(l) records the number of bonded (1 2) interactions, etc. Unbranched acyclic chains have frequency distributions which decrease linearly with increasing INBS (e.g., 5,4,3,2,1 for n-hexane), whilst any branching or ring formation results in a distribution which is restricted to lower INBS values (e.g., 6,6,3,0,0 for cyclohexane). 

On completion of the functional group recognition the first class of objects, i.e., acyclic chains bearing heteroatoms and linked with chemical functionality, are fully selected from the input structure, hierarchically ordered or ranked, and preliminarily identified to an extent enabling their naming. Further phases of the naming cycle must identify the other two classes of objects, i.e., ring systems and chains,... 

---