Chlorine atoms specificity

In a process similar to that described in the previous item, the stored data can be used to identify not just a series of compounds but specific ones. For example, any compound containing a chlorine atom is obvious from its mass spectrum, since natural chlorine occurs as two isotopes, Cl and Cl, in a ratio of. 3 1. Thus its mass spectrum will have two molecular ions separated by two mass units (35 -i- 2 = 37) in an abundance ratio of 3 1. It becomes a trivial exercise for the computer to print out only those scans in which two ions are found separated by two mass units in the abundance ratio of 3 1 (Figure 36.10). This selection of only certain ion masses is called selected ion recording (SIR) or, sometimes, selected ion monitoring (SIM, an unfortunate... 

This, the mass per unit volume, is a function of the weight of individual molecules and the way they pack. The hydrocarbons do not possess heavy atoms and therefore the mass of the molecule per unit volume is rather low. Amorphous hydrocarbon polymers generally have specific gravities of 0.86-1.05. Where large atoms are present, e.g. chlorine atoms, the mass per unit volume is higher and so PVC, a substantially amorphous polymer, has a specific gravity of about 1.4. 

The resultant close packing and the heavy chlorine atom result in the polymer having a high specific gravity (1.875) and a low permeability to vapours and gases. 

Applicahility/Limitations Hydrolysis is suitable for pretreating difflcult-to-treat wastes and for organics with substituents, such as phenols or chlorinated organics with reactive chlorine atoms. Hydrolysis is specific for only a limited number of contaminants. 

Another reaction mechanism that occurs in some chain-growth polymers is solvolysis. In this type of reaction, a species reacts with a C-X bond, where X represents a halogen, and breaks it. Specifically, this becomes important when describing the degradation of polyvinyl chloride. Acidic species act to remove the chlorine atom, forming hydrochloric acid. 

Allenylcobaloximes, e.g. 26, react with bromotrichloromethane, carbon tetrachloride, trichloroacetonitrile, methyl trichloroacetate and bromoform to afford functionalized terminal alkynes in synthetically useful yields (Scheme 11.10). The nature of the products formed in this transformation points to a y-specific attack of polyhaloethyl radicals to the allenyl group, with either a concerted or a stepwise formation of coba-loxime(II) 27 and the substituted alkyne [62, 63]. Cobalt(II) radical 27 abstracts a bromine atom (from BrCCl3) or a chlorine atom (e.g. from C13CCN), which leads to a regeneration of the chain-carrying radical. It is worth mentioning that the reverse reaction, i.e. the addition of alkyl radicals to stannylmethyl-substituted alkynes, has been applied in the synthesis of, e.g., allenyl-substituted thymidine derivatives [64],... 

Today we know that CFCs break up when they reach the ozone layer, releasing chlorine atoms. The chlorine atoms destroy ozone molecules faster than the ozone can regenerate from oxygen gas. Studies in the past ten years have shown dramatic drops in ozone concentration at specific locations. Since ozone protects... 

The second synthetically useful general transformation of any of the chloro esters 1,2 consists of an intra- or intermolecular nucleophilic substitution of the chlorine atom in any of the Michael adducts. Several examples of such reactions have been mentioned above (Table 1 and Scheme 26), and substitutions of any specific importance (for example, with hydride or azide anion [9,10,62]) as well as subsequent transformations of such substitution products will be discussed in the corresponding Sections [66]. 

When irradiating a neon-chlorine mixture chlorine, mono[ F]fluoride (CI[ F]F) of high specific activity can be obtained [45], In electrophilic reactions this reagent would rather introduce the less-electronegative non-radioactive chlorine atom. However, addition to a double bond should be feasible as has been shown for bromine [ F]fluoride (Brp F]F) prepared more recently from activated [ F]fluoride [64-66],... 

Hence, by substitution of 2 chlorine atoms by two methoxy groups the Ki(m value is lowered by one order of magnitude. Such insights are used by chemical manufacturers to adjust chemical properties to suit specific purposes. 

Dihydrotetrazolo[5,l-cf][l,5]benzothiazepines (102) were synthesized by nitrous acid treatment of 2,3-dihydro-1,5-benzothiazepin-4-ylhydrazines (101), which were prepared from 2,3-dihydro-l,5-benzothia-zepine-4(5//)-thiones (84) by reaction with hydrazine hydrate in tetrahydrofuran (THF) (Scheme 31) (88JHC1399 89MI2 93F665). The ability of compounds 103 to displace specific [3H]flunitrazepam binding was studied. Only compounds with a chlorine atom at the 9-position were able to interact with [3H]flunitrazepam binding sites (93F665). 

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