Parent penta

Among the parent hydrides, phosphorus triamide (triaminophosphine) (7.3a) and the tetra aminophosphonium cation (7.3b), are known. The parent penta and hexa-amides (7.3c) and (7.3d) remain hypothetical compounds although derivatives with up to five and six P-N linkages are known, for example, (7.4). 

Penta (or higher) coordinate "nonclassical" ions (carbonium ions) CH5 is parent... 

The multiplying affixes di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-, undeca-, and so on are used to indicate a set of identical unsubstituted radicals or parent compounds. The forms bis-, tris-, tetrakis-, pentakis-, and so on are used to indicate a set of identical radicals or parent compounds each substituted in the same way. The affixes hi-, ter-, quater-, quinque-, sexi-, septi-, octi-, novi-, deci-, and so on are used to indicate the number of identical rings joined together by a single or double bond. 

The tri-, tetra-, penta-, and hexahydrates of boron phosphate have been reported. AH of these decompose rapidly in water to give solutions of the parent acids. Anhydrous boron phosphate hydroly2es in a similar fashion, though the reaction proceeds quite slowly for material that has been ignited at high temperatures. 

Dihydroxypyridazines are readily prepared from the diene 103 and DEAZD or PTAD,159 and the amino acid 104, a constituent of the Monamycin antibiotics, was synthesized from the Diels-Alder adduct of phthalazine-l,4-dione and penta-2,4-dienoic acid.160 These unusual amino acids can also be synthesized from the PTAD and parent HTAD adducts of penta-2,4-dienoic acid,161 and a variety of similar adducts, triazolo-pyridazines 105, has been synthesized from a wide range of 4-substituted 1,2,4-triazole-3,5-diones.162... 

This type of compound (152 to 155) containing one Pni, or tetra- and penta-coordinated Pv atom have been described.(1967,138anai39 1968,123 1969, ii6) Heterocycles with two P-heteroatom bonds in the ring have been more commonly reported. In addition to the numerous Pv oxyphos-phoranes and homologs, synthetised by Ramirez and co-workers (see 1968,124 for a review of these compounds) and by others,(1967,121,140 and 141 1969,147) parent tri-, tetra- and penta- coordinated phosphorus heterocyclics with various structures (156 to 162) are known.<1965,32 ... 

The mono- and diprotonated carbocations and the two-electron oxidation dications derived from parent pyrene and its nonalternant isomers azupyrene (dicyclo-penta[e/, /]heptalene) (DCPH) 72 and dicyclohepta[eJ,g /z]pentalene (DCHP) 73 were studied at the B3LYP/6-31G(d) level (Fig. 29). The most likely site(s) for mono-and diprotonation were determined based on relative arenium ion energies and the structures of the energetically most favored carbocations were determined by... 

The non-Kekule compounds we have considered so far are all stmcturally related to TMM and TME, and the disjoint and parity methods for predicting qualitatively the ground-state spin give similar results. However, the two methods do not agree in the case of another type of non-Kekule structure, of which the parent compound is the biradical 2,3,4-trimethylenepentane-l,5-diyl (56), commonly called penta-methylenepropane (PMP) (Scheme 5.11). 

Within the general description of ligand exchange, the relative stability of a variety of magnesium-olefin complexes/magnesacycles has been studied. For example, 1,4-diphenylbutadiene replaces the parent butadiene in equation 20 to form the penta-coordinated magnesium compound. ... 

While squalene, the parent of all triterpenoids, is a linear acyclic compound, the majority of triterpeneoids exist in cyclic forms, penta- and tetracyclic triterpenes being the major types. Within these cyclic triterpenoids distinct structural variations lead to several structural classes of triterpenoids. Some of the major structures types of triterpenoids are shown helow. 

Clear, unequivocal experimental evidence has by now been obtained for nonclassical ions such as the norbomyl cation.38 10 The bonding concept required to define nonclassical ions is simply to consider them as penta(or higher)-coordinated carbonium ions involving at least one two-electron three-center (or multicenter) bond, of which CH5+ (themethoniumion-carbonium ion) is the parent, asCH3+ (the methenium ion, methyl cation, carbenium ion) is the parent for trivalent carbenium ions. An example of a hexacoordinate carbonium ion is the pyramidal dication of Hogeveen.41... 

The attempts to apply both of the above-described reactions for the preparation of the parent heterocycle 22 (R1 = R2 = H) with the use of penta-l,4-diyn-3-one were only partially successful. The yields of 22 (R1 = R2 = H) were lower than 5%, the main products being unidentified oligomers (92MI3). The first synthesis of 22 (R1 = R2 = H) of preparative significance was when l,5-bis(trimethylsilyl)penta-l,4-diyn-3-one was the... 

Pentachlorophenol, a widely used wood preservative, is considered to be moderately biorefractory with a biodegradation rate constant of 3 x 1012 L/ cell/hr, a log of 5.01, and a vapor pressure of 1.1 x 10-4 mmHg at 20°C. Watts et al. (1990) carried out completely mixed batch tests by treating penta-chlorophenol-contaminated soils with Fenton s reagent. Mineralization of pentachlorophenol (PCP) was studied in commercially available silica sand and two natural soils by removal of parent compound and total organic carbon with corresponding stoichiometric recovery of chloride. The soluble iron concentration decreased over the first 3 hr of treatment, and the concentration remained relatively constant thereafter. A possible mechanism for iron precipitation was proposed as follows ... 

Little interest has been shown in sulfur-containing compounds other than the parent thione (229) which is formed in excellent yield when phenanthridone is heated in pyridine with phosphorus penta-sulfide.214 No data are available on the reactions of 6-chlorophenanthridine with mercaptans or thiophenols. 

The parent cyclopentadienyl cation 1+ has been calculated at various levels of theory [6, 7], and has been found to have a triplet ground state. Its existence as a triplet species in an SbFs matrix at 75 K had previously been proved by ESR spectroscopy [8]. Prior to that, the penta-chlorocyclopentadienyl cation 7+ (Figure 2) had been generated, also in an SbFs matrix at 77 K, and identified as a triplet on the basis of its observable ESR spectrum [9]. The penta-arylcyclopentadienyl cations 8+ [10], especially those with donor-substituted aryl substituents [11], are stable in solution up to 233 K, coexisting as singlet and triplet species due to the small energy difference between them. 

The mono and dichlorobenzenes do not show parent negative ions at 373 K or 523 K. This does not imply that the electron affinity is negative, but rather that other processes occur. Both dissociative and nondissociative capture are observed for the tri and tetrachlorobenzenes. For the penta and hexachlorobenzenes no dissociative attachment is observed. For the biphenyls with two chlorines ion molecule reactions predominate. With three chlorines, two on one ring and the third on the other ring, molecular ions are observed at 373 K. With four or more chlorines molecular ions are observed at both high and low temperatures, and dissociative electron... 

Diazotization by sodium nitrite in a dilute solution of sulfuric acid has been used to convert amino groups of neomycin B at the 6 - and 6" -positions to a hydroxyl group to make paromomycin 1 (120), the 6" -deamino-6" -hydroxyparomomycin 1 (121), and the 6" -deamino-6" -hydroxyneomycin B (122). These compounds were found to be less active than the parent antibiotic, particularly the tetra-amino derivative 121, which was the least active compound, showing about one-tenth the activity of penta-amino derivative 120 or 122 (compounds 120-122 ). These results indicated... 

The major routes of excretion of PCBs are fecal and urinary. For higher chlorinated congeners such as penta- and hexachlorobiphenyls, the predominant route of excretion is via the feces (up to 60% of total excretion) for lower chlorinated congeners, the situation seems to reverse (Lutz and Dedrick 1987). Mainly metabolites are found in urine and bile, although small amounts of parent compound may appear in the feces, in particular congeners that are poorly metabolized such as 2,2 4-,4 5,5 hexaCB. Elimination kinetics tend to follow first-order processes with elimination rates directly related to their metabolic rates (Gage and Holm 1976). An important route of PCB elimination is milk. This varies considerably with the species due to volume and lipid content of the milk, but the basic mechanisms are the same for all species. Because PCBs are in dynamic equilibrium with all tissues, they move passively from blood to milk at the beginning of lactation to maintain their respective tissue/blood ratios. 

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