Loss, parental

Parent Daughter Losses Parent Daughter Losses... 

Several MS acquisition and data processing strategies are used for detection and structure elucidation of metabolites. The common metabolite detection strategies are summarized in Section 9.2.1, which include full MS scan, constant neutral loss, parent ion scan, multiple reactions monitoring, and mass defect filtering. The structure elucidation strategies feature product ion scan, multistage scan, and accurate mass measurement, which are reviewed in Section 9.2.2. 

The ion (M +) derived from the parent molecule by loss of an electron is called a molecular ion. Depending on the structure of substance M and the energy of the incident electron, the resulting ion (M"+) may break up (fragment) to give ions of smaller mass (A+, B, etc.). 

Constant neutral loss (or fixed neutral fragment) scans. The linked scan at constant B[1 -(E/Eg)] /E gives a spectrum of all product (daughter) ions that have been formed by loss of a preselected neutral fragment from any precursor (parent) ions. 

The most common modes of operation for ms/ms systems include daughter scan, parent ion scan, neutral loss scan, and selected reaction monitoring. The mode chosen depends on the information required. Stmctural identification is generally obtained using daughter or parent ion scan. The mass analyzers commonly used in tandem systems include quadmpole, magnetic-sector, electric-sector, time-of-flight, and ion cyclotron resonance. Some instmments add a third analyzer such as the triple quadmpole ms (27). 

Electron Capture and /5" "-Decay. These processes are essentially the inverse of the j3 -decay in that the parent atom of Z andM transmutes into one of Z — 1 andM. This mode of decay can occur by the capture of an atomic electron by the nucleus, thereby converting a proton into a neutron. The loss of one lepton (the electron) requires the creation of another lepton (a neutrino) that carries off the excess energy, namely Q — — Z(e ), where the last term is the energy by which the electron was bound to the atom before it was captured. So the process is equivalent to... 

R designates a substituent group derived from a parent hydride by loss of a hydrogen atom. 

Cations, radicals and anions can be formally considered as being derived from a parent compound by loss of H , H- or respectively. Cations are also commonly considered as being formed by addition of to a site bearing an unshared electron pair. The result of such processes can be indicated by adding suffixes, modifying them, or modifying a prefix. This discussion is confined almost entirely to examples in which the affected site is part of a heterocyclic ring. 

Most heterocyclic anions may be considered to be derived by loss of a proton from a parent compound, which is therefore the conjugate acid. Such anions have at least one unshared pair of electrons at the anionic site. They are named by appending the suffix -ide , with elision of a terminal e (lUPAC recommendation RC-83.1.1), as in (190)-(193). The site may be specified by a locant placed immediately before the suffix, and so chosen as to be as low as possible consistent with the numbering of the skeleton of the parent compound. The locant may be omitted in order to designate an equilibrating mixture of positionally isomeric anions, which is what one usually obtains in practice. The anion of piperidine is often informally referred to as piperidide . 

It is common for names of simple heterocyclic carbonyl derivatives to be contracted, with loss of the -ine ending of the parent name, e.g. pyridone, quinolone, acridone, pyrrolidone, thiazolidone. 

The mass spectra of alcohols often completely lack a peak corresponding to the parent ion. This is due to extremely rapid loss of neutral fragments following initial ionization. For example, the mass spectrum of 2-methyl-2-butanol lacks a parent peak and contains strong peaks at M-15 (loss of CH3O and M-18 (loss of H2O). 

Both 1- and 2-naphthylhydrazine have been shown to react in good yield with 2-hydroxy-3-naphthoic acid in the presence of sodium bisulfite to give, after acidic workup, dibenzocarbazole 30 and 31, respectively7 When either 1- or 2-naphthylhydrazine is heated with sodium bisulfite, dibenzocarbazoles 32 and 31, respectively, are isolated after acidic work-up7 It is suggested that loss of the hydrazine residue to form a bisulfite addition compound of the parent naphthol occurs initially further reaction of this adduct with naphthylhydrazine then affords, after work-up, the products. 

Tlie mass spectra of the parent 3-nitro-l,X-naphthyridines (X = 5,6,7, and 8) and their amino and chloro derivatives feature as main fragmentation pathway the loss of a molecule of NO2 from the molecular ions and further consecutive expulsion of two molecules of HCN. A second fragmentation pathway, although of much smaller intensity, is the loss of NO from the molecular ions, followed by consecutive expulsion of CO and HCN (82MI1 89MI1). 

Soil reaction (pH) The relationship between the environment and development of acid or alkaline conditions in soil has been discussed with respect to formation of soils from the parent rock materials. Soil acidity comes in part by the formation of carbonic acid from carbon dioxide of biological origin and water. Other acidic development may come from acid residues of weathering, shifts in mineral types, loss of alkaline or basic earth elements by leaching, formation of organic or inorganic acids by microbial activity, plant root secretions, and man-made pollution of the soil, especially by industrial wastes. 

Molecular ion (Section 12.1) The cation produced in the mass spectrometer by loss of an electron from the parent molecule. The mass of the molecular ion corresponds to the molecular weight of the sample. 

Besides a parent ion, the mass spectra of benzo- and dibenzothiepins show the corresponding naphthalene or phenanthrene radical cations as the base peak.2-16 The mass spectra of 1-benzo-thiepin 1-oxides and 1,1-dioxides show the same naphthalene radical cation, formed by loss of sulfur monoxide or sulfur dioxide, respectively.14 In contrast, in the mass spectrum of 2,7-di-terf-butylthiepin peaks resulting from the loss of sulfur are not found.17... 

The greater lability of 1-benzothiepin 1-oxides, compared to the parent compounds, may lead to differences in chemical behavior. Thus, treatment of the tricarbonyliron complex of 1-benzo-thiepin 1-oxide (8, X = SO) with ammonium cerium(IV) nitrate in acetone at — 30 °C leads, with the loss of sulfur monoxide, to naphthalene. In contrast, the iron ligand can be removed selectively from the corresponding 1-benzothiepin by ammonium cerium(IV) nitrate.23 92 For the synthesis of 1-benzothiepin 1-oxide, see Section 2.1.4.1,... 

The thieno unit of thienothiepin 1 reacts with iV-phenylmaleimide at 150 C to give the Diels-Alder exo-product 2, with the loss of sulfur.71 Furanothiepin 3 (X = S) and its corresponding 5-oxide or 5,5-dioxide react readily with the same dienophile at room temperature, but in different ways. While the parent compound 3 and its oxide (X = S, SO) form the cycloadduct 4 with loss of sulfur, the dioxide gives a stable Diels-Alder adduct 5 (mixture of endojexo-isomers) which, upon heating above 100 C, loses sulfur dioxide to provide the sulfur-free adduct.70... 

The reaction fails if the decarboxylation produces a radical that is easily oxidized, such as an a-hydroxyalkyl radical.2 In intermediate cases, such as tert-alkyl or a-alkoxyalkyl radicals,2 the yield based on the parent quinono is usually improved by using an excess of persulfate and carboxylic acid to compensate for the loss of radicals due to oxidation (footnote b, Table I). 

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