Phosphate diester

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... 

Following Its formation D fructose 6 phosphate is converted to its corresponding 1 6 phosphate diester which is then cleaved to two 3 carbon fragments under the mflu ence of the enzyme aldolase... 

In contrast to monophosphates, starch phosphate diesters contain cross-links between two or more starch chains. This covalent linkage in the granule produces a starch product which swells less but is more resistant to heat, agitation, and acid than natural starch. 

Teichoic acids (16) are bacterial polymers in which alditols, glycerol, or ribitol are joined through the primary hydroxyl groups via phosphate diester linkages. 

Phosphonomannans (7) are bacterial polymers in which maimo-oligosaccharides are joined by phosphate diester linkages. Phosphonogalactans are present in certain fungi. 

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. ... 

The term polysaccharide has also been widely used for macromolecules containing glycose or alditol residues in which both glycosidic and phosphate diester linkages are present. 

A gel of diesel or crude oil can be produced using a phosphate diester or an aluminum compound with phosphate diester [740]. The metal phosphate diester may be prepared by reacting a triester with phosphorous pentoxide to produce a polyphosphate, which is then reacted with an alcohol (usually hexanol) to produce a phosphate diester [870]. The latter diester is then added to the organic liquid along with a nonaqueous source of aluminum, such as aluminum isopropoxide (aluminum-triisopropylate) in diesel oil, to produce the metal phosphate diester. The conditions in the previous reaction steps are controlled to provide a gel with good viscosity versus temperature and time characteristics. All the reagents are substantially free of water and will not affect the pH. 

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... 

The phosphate diesters (02P(0R)2), ethyl-4-nitrophenyl phosphate and bis(4-nitrophenyl)phos-phate in c/.v-[(en)2Ir(OI I)(02P(0R)2]1, react intramolecularly with the as-OH group at pH 8 to liberate nitrophenolate.22... 

Hawthorne and co-workers have reported the selective uptake of homogeneous flourescein-labeled nzYfo-carboranyl oligomeric phosphate diesters nido-OPDs) by cell nuclei within 2h after microinjection. The location in the cell of nido-OPDs uptake was found to depend on the location of the carboranyl moiety in the nido-OPDs. When the carborane cage was located on a side chain attached to the oligomeric... 

An estimate of the rate enhancement associated with the intramolecular phosphorylation can be made by using isopropyl p-nitrophenyl methyl-phosphonate as a model for the covalent intermediate formed in the initial step of the reaction of cycloheptaamylose with bis (p-nitrophenyl) me thy 1-phosphonate. The first-order rate constant for the alkaline hydrolysis of isopropyl p-nitrophenyl methylphosphonate at pH 9.86 can be obtained from the data of van Hooidonk and Groos (1970) kun = 1.4 X 10-5 sec-1. This value may be compared with the maximal rate constant for the reaction of cycloheptaamylose with bis(p-nitrophenyl) methylphosphonate— k2 = 1.59 X 10-1 sec-1 at pH 9.86—which must be a minimal value for the rate of the intramolecular phosphorylation. This comparison implies a kinetic acceleration of at least 104 which is similar to rate enhancements associated with the formation of cyclic phosphates from nucleoside phosphate diesters. 

Many of the reagents developed initially for the recovery of base or radioactive metals have also been investigated as potential PGM extractants, e.g., phosphine oxides,310-313 dialkylsulfoxides,314 dialkyl-and diphemd-thioureas,296,315-317 thiopicolinamides, thiobenzanilide,319 phosphate diesters,320 tetra-... 

Lipids are biological molecules that are soluble in certain organic solvents (whether or not something is a lipid is operationally defined by the solubility). Lipids include a variety of molecules such as triglycerides, phospholipids, and cholesterol. The major type of lipid in membranes is the phospholipid. They re called phospholipids because they all contain a phosphate diester. 

The other phospholipids that you may encounter are based on sphin-gosine. They are derived from serine instead of glycerol but the concept is the same. They have two long, fatty acid chains, a phosphate diester, and a choline-like charged group. This is a neutral lipid. 

The hydrophobic tail is provided by long-chain fatty acids attached to a glycerol backbone. The head group contains oxygen and may be positively charged or neutral. The name of the phospholipid is dictated by the head group. The head and tail are attached through a phosphate diester. 

Transition metal ion and La3 +-catalysis of the alcoholysis of phosphate diesters 308... 

Phosphate diesters of general structure 29 are among the most resistant species to hydrolysis due the reluctance of hydroxide or even water to attack an anionic... 

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

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