Chloroethyl group

A simOar study has been carried out with the 1-chloroethyl group in the 2-position and the X group in the 4-position. The results are given in Table 111-58 (283, 286). 

Reaction of 256 with phosphorous oxychloride and DMF involves first formylation at the 6-position opening of the ketal to the enol ether by the HC1 produced in the Vilsmeier reaction would afford a hydroxyethyl side chain at C-3. This is no doubt converted to a chloroethyl group by excess oxychloride. There is thus obtained the antiinflammatory agent formocortal (257). 77... 

The synthetic strategy described allowed the synthesis of /V-morpholino-1,2-oxaphosphole derivatives [134], as well as 1,2-oxaphosphole derivatives, bearing lV-2-chloroethyl group at phosphorus (Scheme 64) [135],... 

As previously stated (p. 53) di-(2-chloroethyl) phosphoro-fluoridate can be prepared by the action of phosphorus oxydi-chlorofluoride on ethylene chlorohydrin. The compound can also be prepared by the fluorination of di (2-chloroethyl) phos-phorochloridate, prepared from di-(2-chloroethyl) hydrogen phosphite (XVIII), obtained by the action of phosphorus trichloride on ethylene chlorohydrin. This partial fluorination was effected by means of sodium fluoride, although the yield was not high. The chlorine atoms of the 2-chloroethyl groups were not affected by this procedure, a fact which falls into line with the observations of Saunders and Stacey (p. 12) that ethylene chlorohydrin is not readily fluorinated by sodium fluoride, but only by potassium fluoride under pressure in a rotating autoclave.1... 

The 2-chloroethyl group, which is often an effective toxo-phore, was then attached to phosphorus through oxygen. No reaction appeared to take place between ethylene chlorohydrin and diethyl phosphorochloridate in the absence of a tertiary base. In the presence of pyridine, however, which removed the hydrogen chloride formed, a smooth reaction took place at 0° with the formation of diethyl 2-chloroethyl phosphate,... 

P. Crews and E. Kho-Wiseman, J. Org. Chem., 1977, 42, 2812 formula (20) of this paper should have a chlorovinyl group instead of a 2-chloroethyl group. Plocamene B and plocamene D are reported here without comment, with absolute stereochemistry the same as violacene 2 (cf. refs. 297, 300). 

Syntheses of Polymeric Photosensitizers and Self-sensitized Polymers by the Reactions of PCVE. Photosensitizer monomers such as NPVE, NNVE and NPEVE were synthesized by the reaction of excess CVE with potassium salts of the corresponding photosensitizing compounds using TBAB as a phase transfer catalyst as described in the experimental part. Substitution reactions of chloroethyl groups in PCVE with PNP and PNN were also carried out using TBAB as a phase transfer catalyst in DMF at 80 C for 24 h. 

Substitution reactions of the remaining pendant chloroethyl groups in PCVE-NPVE with 20 mol-% excess of potassium cinnamate were carried out using TBAB as a phase transfer catalyst in DMF at 100"C for 24 h. The reaction conditions and results are summarized in Table III. It should be noted that 100 mole % substitution occurred in all cases. 

The activity of nitrogen mustards depends on the presence of a Z>/s-(2-chloroethyl) grouping ... 

By treating dyes that contain a chloroethyl group with thiourea, the cationic charge may be introduced in the form of an isothiouronium residue (e.g., 55) [150],... 

The molecular ion signals in the mass spectra of the nitrogen mustards are weak (<5%), and the peak originating from the 2-chloroethyl group (mlz 63/65) is rather prominent (>20%). 

These polymers are essentially less toxic (factor of 2-10 at LDs0) and partially very much longer active than free sarkolysin. An increase in activity, however, is not attained. Here, the mode of action is, however, not clear because bifunctional chloro-alkylamine derivatives ( N-Lost derivatives) seem to be necessary to show some activity. Possibly in this case the alkylpyridinium compound decomposes into a derivative of ethylene or the chloroethyl group is formed again so that a second reactive group is formed besides the chloroethyl residue which is still present. 

Due to the high nucleophilicity of oxazoline monomers, their polymerization may be initiated by C—Cl bond even in the absence of silver salt. Thus, chloromethylated polystyrene [290] or polychloroprene [291] were used to prepare corresponding graft copolymers. More recently, polyoxazoline was grafted on poly(vinyl ether)s containing certain proportion of chloroethyl groups [292],... 

Later experiments on the action of chlorine on dichloroethyl sulphide have demonstrated that the chlorination is not limited to one chain of the molecule, but can take place in both the chloroethyl groups, and the following compounds have been prepared ... 

The limitation of the methods appears to be the solubility of the material to be analysed, and possible steric hindrance effects. Substituted siloxysilyl, olefinic, nitrile, silicon hydride, y-chloropropyl or / -chloroethyl groups do not interfere. Perchloric acid does not appear to attack the methyl ether groups in methoxyethoxysilanes. Water and silanol, within limits, do not interfere. Compounds containing acid groups, however, must first be analysed for titratable acid and appropriate corrections made in the alkoxy content calculations. 

Although aziridine derivatives and nitrogen mustard derivatives differ in structural respects, they presumably act in the same way. Nitrogen mustards readily form a cyclic aziridinium ion which reacts in the subsequent rate-controlling step in an S 2 process with an available nucleophilic Y. This process is repeated with a second chloroethyl group and a second nucleophilic Z (Bartlett el al., 1947 Montgomery el al., 1970). 

Figure 2 (a) Ribbon diagram of the monomeric structure of DhiA. For clarity, a-helices are shown in cyan and /3-strands in purple. The location of the active site is indicated by the bound chloride ion, which is shown as a red sphere, (b) A close-up of the active site of DhIA where Asp-124 is covalently modified by a chloroethyl group, which results from the nucleophilic attack of Asp-124 on 1,2-dichloroethane (Figure 3). For clarity, both the chlorine atoms of the chloroethyl group and the displaced chloride ion are shown in yellow. The roles of the key active site residues (Glu-56, Asp-124, Trp-125, Trp-175, Asp-260, and Flis-289) and their interactions are discussed in the text. The figure was prepared with F>yMOL (W. L. DeLano, The PyMOL Molecular Graphics System-, DeLano Scientific San Carlos, CA, USA, 2002, http //www.pymol.org.).

A 1-chloroethyl group can be introduced into aromatic compounds by the reaction 682... 

In class B are placed all simple esters, CHjF CO i , of fluoro-aoetic acid, where iZ = Me, Et, Pr , Pr , Ph, etc. When substitution takes place in the a-hydrogen atoms, e.g. in methyl a-fluoropropionate or a-fluoroisobutyrate, then the compound is devoid of toxicity. This indicates the importance of the unsubstituted fluoromethyl group. On pp. 125 et seq. it was shown that fluoroacetamide and a variety of substituted amides such as CHjF CO NH CHg CHjCl were, molecule for molecule, equally toxic with fluoroacetic acid and produced the same symptoms. The 2 chloroethyl group therefore contributed nothing appreciable to the toxicity of the molecule. The majority of the esters of fluoroethanol showed the toxicity of the parent alcohol, e.g. 2-fluoroethyl chlorosulphonate, CHgF CHg O SOjCl, di-(2-fluoroethyl) sulphate and 2-fluoroethylglycine hydrochloride. 

In fact, another common name for 3,3 -dichloroethyl sulfide is 3,3 -dichloroethyl thioether. The 3 refers to the second carbon away from the sulfur. The prime on the second 3 refers to the second chloroethyl group. 

More specifically, the chlorine on the second chloroethyl group is also on a 3 carbon. Therefore, the structural formula is ... 

Pyrolysis of the 3,3-bis-(2-chloroethoxy)-5cx-androstane derivative (368) gave the A -enol ether (369), which afforded the 2a,3a-methano-derivative (370) with the Simmons-Smith reagent. The 2-chloroethyl group was easily removed by n-butyl-lithium to give the cyclopropanol (371), which rearranged on melting to give the 2a-methyl-3-ketone (372). °... 

The common structural feature of all sulfur mustards is that their molecules are composed of two chloroethyl groups attached to a sulfur atom. Some compounds may have additional S and/or O atoms bridging —CH2—CH2— units. It may be noted that in all these compounds, both the chlorine atoms... 

Chlormethiazole is metabolized in the liver at a high rate and is excreted in the urine mainly in the form of inactive metabolites. The proportion of unchanged substance is usually less than 5% of the applied dose. The biological availability therefore increases in patients with impaired liver function. Metabolic deactivation proceeds by stepwise oxidation of the chloroethyl group to 4-methylthiazole-5-acetic acid. Other routes are shown in Fig. 8-36. The main metabolites in urine are the 1- and 2-hydroxyethyl derivatives. Some metabolites are excreted as conjugates [44],... 

Spectrum. On the other hand, this band is revealed in the spectrum of the styrene-0.6% DVB copolymer intensively crosslinked with 1 mol of MODE, which contains a comparable amount (1%) of pending chlorine. It is quite possible that industrial MN-200 contains chlorine of a different kind. A part of rather inert chlorine in the form of chloroethyl groups may have originated by the involvement of EDO into the Friedel—Crafts reaction. One may also assume that the initial copolymer of that product incorporates more DVB thus the unreacted pendent double bonds may have interacted with MCDE during the post-crosslinking reaction, leading to the formation of methyl chloropropyl ether fragments [105] ... 

No common structural denominator is apparent between the organophosphates to which this biological effect may be attributed, although the inclusion of a 2-chloroethyl group has been considered to lead to neurotoxicity whereas diethylphosphate compounds are devoid of this effect [107]. 

---