Trialkyl lead chlorides

The chemical complexing-solvent extraction technique employed in this work involved the formation of a neutral complex in the aqueous phase between trialkyl lead chloride and a dithiocarbamate reagent such as sodium diethyl di-thiocarbamate. The complex was subsequently removed either as a precipitate or by extraction into an organic solvent. The extent of lead removal was traced by analysis of the aqueous phase for residual trialkyl lead using a Pye-Unicam 8000 spectrophotometer. 

Of the complexing reagents investigated, sodium diethyl dithiocarbamate proved on a number of counts to be the most effective. The bulk of experiments therefore used this compound. The nature of this complex between the reagent and trialkyl lead chloride was first characterized in the absence of sodium chloride in the aqueous phase. 

Trialkyl-lead hydrides and dialkyl-lead dihydrides were made by reducing the corresponding chlorides with lithium aluminium hydride at low temperature (- 78°)36p 37.38,... 

Inefficiencies ia the reaction with POCl leads to alternative production of trialkyl phosphates by employing the sodium alkoxide rather than the alkyl alcohol itself Dialkyl aryl phosphates are produced ia two steps. The low molecular weight alcohol iavolved (eg, butyl) first reacts with excess POCl. The neutral phosphate ester is then completed by the iatermediate chloridate reacting with excess sodium arylate ia water. 

Using acyl chlorides of fatty acids in connection with trialkyl phosphite leads to surface-active a-hydroxyalkanephosphonic acids according to Eqs. (37)-(39). 

Secondary amines, such as pyrrolidine, must be alkylated with care too polar a solvent leads to participation of a second nearby polymer-bound alkylant in the formation of a quaternary ammonium salt, along with the desired immobilized trialkyl amine. The exception, as seen above, is diisopropylamine, which refuses to displace tosylate even in the refluxing pure amine, or in hot dimethyl-formamide or other polar solvent, while metal diisopropylamide is notorious as a powerful non-nucleophilic base. However, carboxamide is not difficult to form from (carboxymethyl)polystyrene, again using toluenesulfonyl chloride as condensing agent this can then be reduced to (diisopropyl-ethylaminoethyl)polystyrene, which is of interest as a polymer-bound non-nucleophilic base. ... 

The 3-lactone dimer of dimethylketene can be prepared by pyrolysis of its polyester, which is formed by the base-catalyzed polymerization of dimethylketene " In addition to the rearrangement of the normal dimer described above, the direct dimerization of dimethylketene in the presence of aluminum chloride or trialkyl phosphites leads to the jS-lactone dimer. 

In the preparation of these compounds it has been found advan-iageous to make a paste of the lead dialkyl Iialides, and then add this to the Grignard reagent. The properties of the compounds are similar to those described for the lead trialkyl alkyls. The simplest member of this series, lead dimethyl diethyl, lias given rise to some discussion regarding its physical constants. It was prepared by the action of magnesium methyl iodide on lead diethyl chloride. Its properties are sho vn below ... 

One rather interesting aspect of the Friedel-Crafts reaction is that trialkylation of benzene often leads to a symmetrical 1,3,5-isomer rather than a 1,2,4-derivative as would be expected from the ortho-para orientation of the alkyl group introduced initially. Since alkylation by the Friedel-Crafts method has been shown to be a reversible reaction,68 this anomalous orientation has been explained on the basis that both alkylation and dealkylation occur readily in the ortho and para positions. Simultaneously, however, some alkylation occurs in the meta position but no dealkylation68 If the reaction mixture is allowed to stand in contact with aluminum chloride for some length of time, then principally meta trialkyl derivatives will be formed ... 

As a last example, which completes the series of imaginative syntheses for thiophosphonic dichlorides, in Figure 17 I would like to highli< t the cleavage of alkyl thiophosphoryl chlorides and trialkyl tetrathiophosphates, which where discussed earlier, with phosphorus trichloride at 300 C, vhich, for example, leads to methyIphosponothioic dichloride as well as thiophosphoryl trichloride (34). 

Condensation of arsenic trihalides with alkyl or aryl halides in the presence of metallic sodium, analogous to a Wurtz-Fittig reaction, leads to trialkyl- and triaryl-arsines. E.g., tribenzylarsine is obtained by prolonged boiling of benzyl chloride and arsenic trichloride in ether containing sodium and a little ethyl acetate 501 tripropylarsine is obtained similarly from propyl chloride, arsenic... 

Side chain polyphosphonate polymers can be obtained from polystyrene by reaction with PCI3 and AICI3 (12.194) and from polyvinyl chloride by reaction with a trialkyl phosphite (12.195). Reaction with cross-linked varieties of polystyrene in (12.186) leads to the production of resins with cation exchange properties [24]. 

The time-dependent UV spectra of mixtures of BI P FeCl2 and MAO at several concentrations show that the interaction of the components leads to several species, which aU are thermally labile. Some transformations are fast (minutes) and some proceed over hours at room temperature [38]. An interpretation is not offered. In the analogous vanadium(III) chloride complex, methylation of the ortho pyridyl carbon is found, leading to an mono-anionic ligand [30]. This reaction or comparable processes may also take place in the case of BIP FeCl complexes and may lead to further catalytic active species with different catalytic actions [39]. The identity of the active catalyst remains to be elucidated, as well as its oxidation state [34, 40-42]. In a recent review, the dissociation of the aluminum trialkyls from the complexes in (1) has been offered as a reaction leading to the actual catalyst (see Scheme 1) [43]. 

Chemical properties of trialkyl REM compounds are studied very poorly. It is established that the easily proceeding hydrolysis of them leads to the quantitative splitting off of RH [43, 45]. The erbium complex reacts with iodine and mercury chloride according to the equations [45] ... 

Orientation in di- or trialkylation may be regulated by controlling the vigor of the reaction. Relatively mild catalysts, such as boron fluoride (with an alcohol), hydrogen fluoride (with an olefin), or ferric chloride (with an alkyl halide), may lead almost excluavely to p-dialky-lation or 1,2,4-tiialkylation. Under more vigorous conditions, as with excess aluminum chloride at elevated temperatures, the m-dialkyl or sym-trialkyl derivative predominates. 

---