Phosphation reagents

A first approach to testing, ASTM D 1094, is to create, using a potassium phosphate reagent, a separation between two layers, hydrocarbon and aqueous. The degree of separation of the two phases is estimated by attributing a grade from 1 to 3 and the appearance of the interface by five levels of observation 1, lb, 2, 3, and 4. The specifications establish both the quality of separation (2 is the maximum) and the appearance of the interface (lb maximum). 

The most effective solvent is sodium hydrogenphosphate, if the detection is not done with phosphate reagent (e.g., Hanes reagent see below). 

Radiolabeled 8-azido purine phosphates, reagents for membranes, heterobifunctional reagents... 

The phosphate reagent is obtained from trichloroacetate and triethyl phosphite. It can bring about the same transformation as diethyl 1 -chloro-1 -ethoxycarbonyl-1-lithiomethanephosphonate described by Villieras 39). 

Commercial calcium aluminate cements reacted with polybasic Na-phosphate reagent Reagent solution contained 30 wt% (—NaPOs—) . One of the aluminate cements contained C A, C2 A S (gehlenite), and C A2. The second cement had C A, C A2, corundum, and C2 A S as the minor phase [6]... 

Nitrophenyl phosphate reagent is stored at -20 °C, allow the substrate to warm to room temperature before opening the container to avoid absorption of moisture. Prepare fresh / -nitrophenyl phosphate solutions (with and without tartrate) in the moment of use. 

Adams SP, Kavka KS, Wykes EJ, Holder SB, Gallupi GT. Hindered dialkyl-amino nucleoside phosphate reagents in the synthesis of two DNA 51-mers. 

A five-fold increase in sensitivity in the detection of aldopentoses on paper chromatograms has been achieved by using a spray reagent composed of diphenylboronic acid and 2-amino-ethanol prior to spraying with a 4-anisidine phosphate reagent. 

ATPase was assayed in a medium containing 25 mM Na2S04, 3 mM MgS04, 10 mM glycylglycin, pH 8. The reaction was started by addition of 3 mM ATP and was stopped after 10 min by addition of phosphate reagent [6]. ... 

The principal phosphation reagents used to manufacture phosphate esters are phosphoric anhydride (P4O10), phosphorus oxychloride [P(0)Cl3], and polyphosphoric acid. It is important to understand the physical and chemical characteristics of each raw material. The structure of the phosphation agent affects its reactivity and selectivity, resulting in variation in the monoester, diester, and triester product distribution. 

In the first step, the alcohol, phosphation reagent, and water (or its equivalent in phosphoric or polyphosphoric acid, calculated as a composite of phosphoric anhydride and water) are combined in accord with the following equation ... 

Since the P2O5 phosphation reagent requires 3 mol of alcohol plus water as reactants to react completely (6 mol per mol of P4O10), it is seen to be purposely in excess with the intent of preferentially forming the monoalkyl pyrophosphate intermediate in the first step. After conversion of the more reactive phosphation reagent and intermediates to pyrophosphates, the remaining amount of alcohol, D, is added in accord with the following equation in the second step ... 

Additional versions of the earlier process [59-61] as well as processes based on phosphation of alcohol/water mixtures with phosphoric anhydride [62,63] have been published. The first group includes added intermediate or postreaction purification steps and steam stripping or other methods to remove residual alcohol. The products resulting from the water/phosphoric anhydride routes are generally not characterized by the combination of a high mono- to dialkyl ratio and low-residual phosphoric acid and alcohol levels associated with the phosphoric acid/phosphoric anhydride hybrid phosphation reagent processes. 

Certain applications require products possessing a higher DAP content than attainable from the sesquiphosphate mixtures derived from phosphoric anhydride. Multiple reaction sites and a lack of selectivity characteristic of the phosphation reagents described earlier make than unsuitable for the preparation of high dialkyl content esters. 

If high pnrity is essential, DAPs can be prepared by the oxidation of the corresponding dialkyl phosphite [67], which is in turn prepared from phosphorus trichloride. To avoid phosphorus halides, a phosphation reagent can be prepared from the reaction of Iowa trialkyl phosphates with phosphoric anhydride, yielding a range of intermediates, depending on the conditions and molar ratio [68]. 

---