Phosphoric Ester Acids

Nucleotides are phosphoric acid esters of nucleosides Those derived from adenosine of which adenosine 5 monophosphate (AMP) is but one example are especially promi nent AMP is a weak diprotic acid with s for ionization of 3 8 and 6 2 respectively In aqueous solution at pH 7 both OH groups of the P(0)(0H)2 unit are ionized... 

Section 28 3 Nucleotides are phosphoric acid esters of nucleosides... 

Amongst heat stabilisers are copper salts, phosphoric acid esters,phenyl-3-naphthylamine, mercaptobenzothiazole and mercaptobenzimidazole. Of these, copper salts in conjunction with halides have been found particularly effective, and some automotive specifications require the use of copper for heat stabilisation. Light stabilisers include carbon black and various phenolic materials. 

The Arbuzov reaction,also called the Michaelis-Arbuzov reaction, allows for the synthesis of pentavalent alkyl phosphoric acid esters 4 from trivalent phosphoric acid esters 1 (Z,Z = R,OR) by treatment with alkyl halides 2. 

Most common is the preparation of alkyl phosphonic acid esters (phospho-nates) 4 (Z,Z = OR) from phosphorous acid esters (phosphites) 1 (Z,Z = OR). The preparation of phosphinic acid esters (Z = R, Z = OR) from phosphonous acid esters, as well as phosphine oxides (Z,Z = R) from phosphinous acid esters is also possible. 

The reaction mechanism outlined below for phosphorous acid esters analogously applies for the other two cases. The first step is the addition of the alkyl halide 2 to the phosphite 1 to give a phosphonium salt 3 ... 

Chemical Name N,N,0-tris-(/3-chloroethyl)-N -(7-hydroxy-n-propyl)-phosphoric acid ester diamide... 

N-(2-Chloroethyl)-N,0-propylene phosphoric acid ester amide HCI Triethylamine... 

The most commonly used stabilizers are barium, cadmium, zinc, calcium and cobalt salts of stearic acid phosphorous acid esters epoxy compounds and phenol derivatives. Using stabilizers can improve the heat and UV light resistance of the polymer blends, but these are only two aspects. The processing temperature, time, and the blending equipment also have effects on the stability of the products. The same raw materials and compositions with different blending methods resulted in products with different heat stabilities. Therefore, a thorough search for the optimal processing conditions must be done in conjunction with a search for the best composition to get the best results. 

This kind of ester acts as a nonionic surfactant if the alkanol groups contain hydrophilic moieties. If only two molecules of alkanoles are added to the phosphoric acid molecule an acid or secondary dialkyl phosphoric acid ester is formed that are an amphiphilic molecule by itself see Eq. (5). 

It possesses surface-active properties in its acid form as well as in the form of its salts. In the case of 1 mol alcohol reacting with 1 mol phosphoric acid, a so-called primary or monoalkyl phosphoric acid ester with two remaining acid groups arises see Eq. (6). 

Phosphoric acid esters having a low content of arsenic can be obtained by treating with 0.1-10% adsorbents such as activated clay, active carbon, alumina, and silica gel to decrease the arsenic content. Thus, 100 parts lauryl phosphate containing 10.3 ppm As and 2 parts activated clay were mixed at 60-70°C for 2 h and filtered to give lauryl phosphate only containing 0.6 ppm As [28]. 

The reaction of condensed phosphoric acid with castor oil gave a poly-phosphoric acid ester, which after neutralization with ammonia shows a high wetting power [32]. Glycerol trioleate was reacted with octametaphosphoric acid at 40°C in the presence of acetic acid anhydride. The reaction product was neutralized with triethanolamine [32,33]. 

Phosphoric acid esters based on alkylene oxide adducts are of great interest. Their properties can be altered by the length and structure of the hydrophobic alkyl chain. But they are also controlled by the kind and length of the hydrophilic alkyleneoxide chain. The latter can easily be tailored by selection between ethylene oxide and propylene oxide and by the degree of alkoxylation. 

Phosphoric acid esters of polyoxyalkylenes of a high degree of alkoxylation still show many properties of the base products [37,38], Thus these products derived from nonionics are only mildly anionic. They have a better performance in such applications as institutional and industrial cleansers with a high percentage of alkaline builders. 

If primary alcohols with a straight chain of 10-20 carbon atoms are initially alkoxylated by a mixture of ethylene and propylene oxides followed by phosphorylation, a pour point depression to 8°C will occur, whereas phosphate esters derived from nonylphenol are liquid at temperatures as low as 2°C. Phosphoric acid esters on the base of linear primary alcohols (Cn-Cl5) generally solidify below 24°C [50] (Table 2). 

Phosphoric acid esters of nonionic surfactants have a greater solubility and compatibility than the nonionics from which they are derived, as shown in Table 3 [37]. 

Although the phosphorous acid esters are often referred to as such, they are not true phosphites [72]. To be more precise, they exist almost exclusively in the phosphonate form of pentavalent phosphorus, as shown in structures (5) and (6) ... 

Nitrogen- or Fluorine-Containing Phosphonates In N-containing phosphoric acid esters an >NH or >NR group is used instead of the bivalent >0. A typical reaction is the transformation of POCl3 with primary or secondary amines to the corresponding amides see Eq. (73) ... 

The solubility of phosphoric acid esters in water and organic solvents is controlled by the chain length of the alkyl groups and the ethylene oxide con-... 

Phosphoric acid esters are strong acids similar to orthophosphoric acid. Potentiometric titration of a 0.1 N aqueous solution of an acid phosphoric acid ester clearly shows two potential jumps which lie at pH values of 6.5 and 11.5. The pH value of diluted aqueous solutions of acid esters lies in the range of 1-3. Phosphoric acid esters are stable against hydrolysis, but adducts of free phosphoric acid esters with ethylene oxide are generally less stable. 

Acid ester phosphates with an alkyl chain up to C6 have little solubility whereas neutralized esters are soluble in water. In ethanol and isopropanol most of phosphoric acid esters and their salts are soluble. If the products are based on ethoxylated alcohols their solubility in water will increase as the degree of ethoxylation increases. The solubility in organic solvents like gasoline, benzene, perchlorethylene, and other apolar liquids recedes with an increase in the degree of ethoxylation but are increased by a higher alkyl chain. 

Because polarity is a dominant factor in solubility, phosphorus-containing anionic surfactants can be tested by solving them in a line of different liquids, e.g., heptane, toluene, propanone-2, ethanol, and water. From the behavior in those liquids the surfactants can be classified for an overall view on the solubility of phosphoric acid esters based on alcohols and ethoxylated alcohols in different surroundings. 

Foamability of phosphoric acid esters in aqueous solutions is in general only moderate, with the acid phosphates showing a better stability against water hardness than the alkali or amine salts. 

Phosphates and phosphonates are valuable contents of cleaners used for technical purposes especially when anticorrosive behavior is also required. Phosphoric acid esters are a component of aqueous cleaning compositions for printed circuit boards [212]. 

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