Aliphatic Chlorides

Cleavage of the C—Cl bond leads to a small Cl+ peak and to a R+ peak, which is prominent in the lower chlorides but quite small when the chain is longer than about C5. 

Loss of HC1 occurs, possibly by 1,3 elimination, to give a peak (weak or moderate) at M - 36. 

FIGURE 1.30 El mass spectrum of carbon tetrachloride (CC14). 

In general, the spectrum of an aliphatic monochloride is dominated by the hydrocarbon pattern to a greater extent than that of a corresponding alcohol, amine, or mercaptan. 

Straight-chain chlorides longer than C6 give 

C4H8C1 ion forms the most intense (sometimes the base) peak a five-membered cyclic structure may explain its stability. 

FIGURE 2.16 (a). Peaks in the molecular ion region of bromo and chloro compounds. Contributions due to C, H, N, and O are usually small compared to those for Br and Cl. 

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Fig. 12.4. Expression systems involving covalent linkages. Numbers correspond to entries (methods) in Table 12.2 (2) labeling of dehalogenase fusion proteins (i.e., HaloTag) with aliphatic chlorides, (4) labeling of AGT (06-alkylguanine-DNA alkyltransferase) fusion proteins with benzylguanine (BG)...

This linear correlation was then assumed to hold for the formation and reaction of aliphatic tertiary carbocations, and values of = 3.5 and 1.6 X 10 s for addition of 50 50 (v/v) water/trifluoroethanol to 5+ and the tert-butyl carbocation, respectively, were estimated from the values of fcobsd for reaction of the corresponding tertiary aliphatic chlorides using Eq. 2. ... 

Brown, H. C., and R. S. Fletcher Chemical effects of steric strains. II. The effect of structure on olefin formation in the hydrolysis of tertiary aliphatic chlorides. J. Amer. chem. Soc. 72, 1223 (1950). 

Aliphatic Bromides The remarks under aliphatic chlorides apply quite generally to the corresponding bromides. 

Tricresyl phosphate Hexanes, heptanes, aromatics, organic sulphur compounds and aliphatic chlorides... 

Simple aliphatic chlorides are chlorosulfonated by a mixture of chlorine and sulfur dioxide in the presence of light. For example, n-propyl chloride gives 3 chloropropanesulfonyl chloride (23%)."... 

Acylations. Catalyzed by graphite the Friedel-Crafts acylation as well as the transformation of ethers to esters by acyl halides in refluxing 1,2-dichloroethane are realized. Although aliphatic chlorides are inferior to aromatic halides this method is quite general as shown by the synthesis of benzoates (e.g., allyl benzoate from allyl benzyl ether and methyl benzoates from methyl f-butyl ether). 

Duprat P, Delsaut L, Gradiski D. 1976. Irritant potency of the principal aliphatic chloride solvents on the skin and ocular mucosis membranes of rabbits. Eur J Toxicol 3 171-177. 

By the action of NaBH4 in the presence of CdCl2 in DMF. This method is compatible with aliphatic chlorides, esters, nitriles, NO2 groups, and double bonds [EB3]. 

Systematic data on the relation between chemical structure or reactivity of chlorine compounds and lubricant additive performance are sparse. Table 11-11 gives some four-ball test data obtained by Mould, Silver and Syrett [35], with the additives listed in order of increasing effectiveness in terms of the wear/load index. The results show numerous departures from expectations based on chemical structure. For example, there is practically as much difference between the wear/load indices for the two primary chlorides, n-hexadecyl (16.2 kg) and n-hexyl (30.4 kg), as for n-hexyl chloride and t-butyl chloride (46.1 kg). A large difference would be expected on the basis of chemical reactivity between the additive effectiveness of primary and tertiary alkyl chlorides, but only a small difference for the two primary aliphatic chlorides. The overall trends are what would be expected in general, primary and aromatic chlorides are less efficacious than secondary chlorides, which in turn... 

Unfortunately it is impossible to estimate these shifts theoretically in any convincing manner, and of course truly reliable interpretations can only be obtained by direct comparison with known spectra of suitable reference compounds containing charged carbon atoms. At the present time infrared spectra of known aliphatic carbonium ions are not available in the literature however, the recent investigations of Baughan and co-workers (141, 142) provided a direct route for obtaining such data. They demonstrated, by cryoscopic and conductivity studies, that stable solutions of aliphatic carbonium ions could be obtained in fused antimony trichloride via ionization of aliphatic chlorides. Conveniently, this solvent is an excellent medium for infrared spectroscopy. In a preliminary study (103) the infrared spectra of the butenyl... 

The most important means of introducing fluorine into aliphatic compounds is the HF substitution of aliphatic chlorides in the presence of pentavalent antimony salts. A common procedure is to add carbon tetrachloride to a stainless-steel autoclave, then introduce antimony penta-chloride, chlorine, and hydrogen fluoride. The autoclave is closed and heated to 100°C until reaction is complete. HCl must be vented at intervals to keep the pressure down to 30 atm. 

C-Cl Stretch (strong) in aliphatic chlorides occurs in the range 785-540 cm . Primary chlorides absorb at the upper end of this range, while tertiary chlorides absorb near the lower end. Two or more bands may be observed, due to the different conformations which are possible. 

C-Br Stretch (strong) in aliphatic bromides occurs at 650-510 cm, out of the range of routine spectroscopy using NaCl plates or cells. The trends indicated for aliphatic chlorides hold for bromides. Aryl bromides absorb between 1075 and 1030 cm . ... 

Aliphatic bromides > aliphatic chlorides = aromatic bromides > aromatic chlorides... 

Identification of chloro and bromo compounds is a relatively simple matter because of the unique isotopic pattern. The presence of fluoro and iodo compounds, although not easy, can be inferred from the conspicuously low [M - -1]/[M] ratio, which is due to the fact that F and I are monoisotopic. The molecular ion in aliphatic chlorides is visible only in lower monochlorides. With an increase in the number of chlorine atoms, the abundance of the molecular ion decreases further. The t-cleavage to expel a halogen atom often produces an abundant ion (e.g., the base peak in the mass spectrum of r-butyl chloride is C4H9+). The a-cleavage is of low consequence in alkyl chlorides, but the loss of an alkyl radical can be prominent when the alkyl chain is longer than four carbons the product is a flve-membered ring halonium ion ... 

Table 17 gives, by way of example, polarizabilities for different molecules in different directions. It is evident that acetylene is particularly easily polarizable parallel to the triple bond, that methane and CCI4 appear entirely symmetrical in excellent agreement with their actual behavior, that CH3CI possess an axis of symmetry, but that higher aliphatic chlorides are asymmetrical And so on. There is very clear evidence concerning... 

In compounds containing both an epoxide ring and an aliphatic chloride, such as epichlorohydrin, the thiolate reacts preferentially with the aliphatic chlorine ... 

Scialdone O, Guarisco C, Galia A, Herbois R (2010) Electroreduction of aliphatic chlorides at silver cathodes in water. J Electroanal Chem 641 14-22... 

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