Esters phosphate diesters

Perhaps the most extensively studied catalytic reaction in acpreous solutions is the metal-ion catalysed hydrolysis of carboxylate esters, phosphate esters , phosphate diesters, amides and nittiles". Inspired by hydrolytic metalloenzymes, a multitude of different metal-ion complexes have been prepared and analysed with respect to their hydrolytic activity. Unfortunately, the exact mechanism by which these complexes operate is not completely clarified. The most important role of the catalyst is coordination of a hydroxide ion that is acting as a nucleophile. The extent of activation of tire substrate througji coordination to the Lewis-acidic metal centre is still unclear and probably varies from one substrate to another. For monodentate substrates this interaction is not very efficient. Only a few quantitative studies have been published. Chan et al. reported an equilibrium constant for coordination of the amide carbonyl group of... 

Esters, see Carboxylate esters Phosphate diesters Phosphate esters Ethidium bromide, binding with DNA, 186-187, 188/, 189-190... 

In the case of phosphates, the triesters are most susceptible to nucleophilic attack and hence the base-catalyzed reaction generally predominates in the pH-rate profile of these esters. Phosphate diesters, with the exception of small ring cyclic ones, are relatively unreactive in neutral... 

Phosphate esters and anhydrides dominate the living world. Major areas of synthetic interest include oligonucleotides (polymeric phosphate diesters), phospho-rylated peptides, phospholipids, glycosyl phosphates, and inositol phosphates. ... 

In the early solution phase syntheses of oligonucleotides, coupling of phosphate diesters was used. A mixed 3 -ester with one aryl substituent, usually o-chlorophenyl, was coupled with a deprotected 5 -OH nucleotide. The coupling reagents were sulfonyl halides, particularly 2,4,6-tri-i-propylbenzenesulfonyl chloride,53 and the reactions proceeded by formation of reactive sulfonate esters. Coupling conditions... 

As we shall see later, most catalytic antibodies achieve rate accelerations in the range 103 to 106. It follows that for a very slow reaction, e.g. the alkaline hydrolysis of a phosphate diester with A 0h 10-u m 1 s 1 direct observation of the reaction is going to be experimentally problematic. Given that concentrations of catalytic antibodies employed are usually in the 1-10 /am range, it has proved far more realistic to target the hydrolysis of an aliphatic ester, with /c0h 0.1 m-1 s-1 under ambient conditions. 

The results of studies concerning reactions between nucleophiles and trimethyl phosphate and trimethyl phosphite should be mentioned briefly. In both esters the nucleophiles may attack the phosphorus centre to react in this way via pentacoordinate and tetrahedral type species, respectively, to products. Various nucleophiles, such as F-, CD30 , DNO , OH and NH2 have been allowed to react with trimethyl phosphate, but only OH and NH have been found to attack the phosphorus centre to a minor extent. The most prominent process is nucleophilic attack on one of the carbon atoms to generate by an SN2 reaction the phosphate diester anion as... 

A mild and efficient deprotection of phosphate triesters involves nucleophilic attack by weakly basic nucleophiles such as iodide, thiolate and amines at the O-C bond with synchronous expulsion of a phosphate diester as the leaving group [Scheme 7.6]. The reaction is especially useful for the deprotection of methyl, benzyl and allyl phosphates as in Scheme 7.8 shown below. An analogous reaction occurs with carboxylic esters but the conditions required are more stringent because the carboxylate anion is a poorer leaving group (see section 6.3.1),... 

CHLOROETHANOL PHOSPHATE DIESTER ESTER with 3-CHLORO-7-HYDROXY-4-METHYLCOUMARIN ... 

CHLOROETHANOL HYDROGEN PHOSPHATE ESTER with 3-CHLORO-7-HYDROXY-4-METHYLCOUMARIN seeDFH600 2-CHLOROETHANOL (MAK) see EIU800 2-CHLOROETHANOL PHOSPHATE see CG0500 2-CHLOROETHANOL PHOSPHATE DIESTER ESTER with 3-CHLORO-7-HYDROXY-4-METHYLCOUMARIN see DFH600... 

Both, alkyl phosphates and alkyl ether phosphates are made by treating the fatty alcohol or alcohol ethoxylates with a phosphorylating agent, usually phosphorous pentoxide, P4OJQ. The reaction yields a mixture of monoesters and diesters of phosphoric acid, with the ratio of the two esters being determined by the ratio of the reactants and the amount of water present in the reaction mixture. The physico-chemical properties of the alkyl phosphate surfactants depend on the ratio of the esters. Phosphate surfactants are used in the metal-working industry, due to their anticorrosive properties. 

Plasticiser Soften polymer, reduce Tg Separates polymer chains from each other Phthalate esters, aliphatic diesters, epoxidised oils, phosphate esters, polyesters... 

Coumarin, 3-chloro-7-hydroxy-4-methyl-, bis(2-chloroethyl) phosphate Di-(2-chloroethyl) 3-chloro-4-nnethylcoumarin-7-yl phosphate Di-(2-chloroethyl)-3-chloro-4-methyl-7-counn-arinyl phosphate 0,0-Di(2-chloroethyl)-0-(3-chloro-4-nnethylcoumarin-7-yl)-phosphate EINECS 206-289-1 Ethanol, 2-chloro-, phosphate diester, ester with... 

Synthetic Methods.—The preparation of phosphate esters by 5n2 attack of phosphate ester anions on carbon is receiving more attention following the realization that the poor nucleophilicity commonly associated with such anions is due to solvation and ion-pairing effects. Thus tetra-methylammonium di-t-butyl phosphate reacts with primary and secondary alkyl iodides in aprotic solvents to give the corresponding triesters (1) from which the t-butyl groups are readily removed by trifluoracetic acid. The proposal of a similar S 2 mechanism in the reaction of triphenylphosphine and ethyl azodicarboxylate with a phosphate diester in the presence of an... 

Protection of a phosphate as its 2-phenylthioethyl ester has been shown to be a useful method in the syntheses of phosphate diesters in the nucleotide field. This protecting group is fairly stable to acid and base but treatment with periodate converts it into the sulphoxide (18), which undergoes rapid elimination in aqueous base (Scheme 4). 

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