Alkylating agents acid esters

Esters of /i-toluenesulphonic acid, which are of great value as alkylating agents, may be prepared by interaction of p-toluenesulphonyl chloride and the alcdiol in the presence of sodium hydroxide solution or of pyridine, for example ... 

Alkylation with other alkylating agents such as ethyl iodide (43. 180, 181j, chloracetic acid and its esters (182). and dialkylaminoalkylhalides (40.43) occurs also on the ring nitrogen. 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

Various alkylating agents are used for the preparation of pyridazinyl alkyl sulfides. Methyl and ethyl iodides, dimethyl and diethyl sulfate, a-halo acids and esters, /3-halo acids and their derivatives, a-halo ketones, benzyl halides and substituted benzyl halides and other alkyl and heteroarylmethyl halides are most commonly used for this purpose. Another method is the addition of pyridazinethiones and pyridazinethiols to unsaturated compounds, such as 2,3(4//)-dihydropyran or 2,3(4//)-dihydrothiopyran, and to compounds with activated double bonds, such as acrylonitrile, acrylates and quinones. 

The mechanisms by which transition-metal oxidizing agents convert alcohols to aldehydes and ketones are complicated with respect to their inorganic chemistry. The organic chemistry is clearer and one possible mechanism is outlined in Figure 15.4. The key intennediate is an alkyl chromate, an ester of an alcohol and chromic acid. 

Amine salts of a-sulfonated fatty acids and esters are also used as antistatic agents. Mixtures of alkyl a-sulfo fatty acid ester diethanolamine salts and hexa-decyl stearate or butyl stearate are coated onto nylon yarn after fiber formation and before stretching [97]. Polypropylene can be made antistatic with an amine salt of a-sulfolauric acid [C10H21CH(SO3Na)COO +NH(CH2CH(OH) CH3)3] [98]. 

Salts of a-sulfo fatty acid esters can work as emulsifying agents for the preparation of asphalt emulsions and asphalt-latex emulsions. The ester sulfonates improve the storage stability of the emulsions [101,102]. In the manufacture of lightweight gypsum products air bubbles have to be mixed into the slurries. The use of salts of sulfonated C10 l8 fatty acid alkyl esters as foaming agents produces uniformly distributed fine bubbles [103]. Salts of C10 16 fatty acid alkyl ester sulfonates can also be added to cement mixtures to prevent slump loss of the mixtures [104]. 

Treating petroleum oils with 3-5% calcium alkyl salicylate and 0.5-3% triethanolamine salts of phosphoric acid esters and ethoxylated dodecyl alcohol increases oxidation-thermal stability at 180-200°C in the manufacture of oil for metal parts quenching. The agent provides also short-term anticorrosion protection of the hardened articles [261]. Phosphoric acid salt alkyl esters are used in anticorrosives and aqueous dispersions in waterborne polyester coatings for metals [244]. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

The electrochemical results suggested to explore the possibility of creating a C-C bond between the electrogenerated a-carbanion fi and carbon nucleophiles. Results of practical importance have hitherto been obtained upon electroreduction of 2-bromoisobutyramides in acetonitrile at Hg or Pt cathodes, in the presence of carbon dioxide and an alkylating agent. The enolate-amide fi undergoes quantitative carboxy-alkylation, to yield ester amides of 2,2-dimethylmalonic acid (ref. 16). 

Two methods for converting carboxylic acids to esters fall into the mechanistic group under discussion the reaction of carboxylic acids with diazo compounds, especially diazomethane and alkylation of carboxylate anions by halides or sulfonates. The esterification of carboxylic acids with diazomethane is a very fast and clean reaction.41 The alkylating agent is the extremely reactive methyldiazonium ion, which is generated by proton transfer from the carboxylic acid to diazomethane. The collapse of the resulting ion pair with loss of nitrogen is extremely rapid. 

The anion derived from ethyl 2-nitropropionate reacts with various reductive alkylating agents (S l substrates) to give new unsymmetrically disubstitutednitro esters (Eq. 5.35), which are interesting precursors for unusual amino acids.53... 

Method A The finely powdered potassium salt of the carboxylic acid (11 mmol) is added to the alkylating agent [ 11 mmol for RX 5.5 mmol for X(CH2) X, 20 mmol with allylic and benzylic halides] and Aliquat or TBA-Br (0.1 mmol). The mixture is shaken vigorously for 15 min and then allowed to stand (see Table 3.9). The mixture is diluted with Et20 (60 ml), filtered through Florisil, and evaporated to yield the ester. 

The quaternary ammonium resin (e.g. Amberlite IRA-904) (2 mol equivalent) and the carboxylic acid (l mol equivalent) are shaken in EtOH (25 ml) for ca. 30 min at room temperature. The resin is collected, washed with MeCN (2 x 15 ml), and added to the alkylating agent (4 mol equivalent). The system is stirred at 20-25 °C for 10-20 h and then filtered. Fractional distillation of the filtrate yields the ester. 

Method C The malonic ester (15 mmol) is stirred with aqueous NaOH (50%, 30 ml) and TEBA-CI (3.54 g, 15 mmol). The alkylating agent (0.25 mmol) is then added and the mixture is stirred for 1 h at room temperature. The mixture is diluted with H,0 (75 ml) and extracted with Et,0 (3 x 25 ml). The dried (MgS04) extracts are evaporated to give the alkylated ester. Acidification of the aqueous phase with cone. HCI and extraction with Et,0 (3 x 25 ml) yields the alkylated malonic acid or r-butyl ester. 

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