Alkyl Esters of Phosphoric Acid - Industrial & …
Alkyl Esters of Phosphoric Acid
Table 4 summarizes some of the phosphorous acid-related compounds and research on their efficacy against potato late blight. In most cases, phosphorous acid is applied to the foliage. The compound is translocated from the shoots to the roots and can, therefore, also control oomycetes that affect roots. Phosphorous acid was shown to be effective when applied as a root drench against P. cinnamomi, P. nicotianae, and P. palmivora in lupin, tobacco, and papaya, respectively (Smillie, Grant, and Guest 1989). The efficacy of different phosphonate compounds against nine Phytophthora spp. that cause stem rot of Persea indica L. and pepper was tested both as a curative and preventive method of control by Ouimette and Coffey (1989a). Although there were notable differences in the sensitivity of the Phytophthora spp. in their experiments (Table 4), there was little variation in the ability of phosphonates to control stem rot of pepper, regardless of its use as a curative or a preventive agent in pots. A greater level of control was obtained for Persea indica L. than for pepper (Ouimette and Coffey 1989a).
Esters of Phosphoric Acid - 2012 Book Archive
A major factor in the ability of phosphorous acid to control oomycetes appears to be its chemical stability in the plant (Smillie, Grant, and Guest 1989). Phosphorous acid does not convert into phosphate and is not easily metabolized (Ouimette and Coffey 1989b). The stability of different phosphonate-related compounds may depend on environmental factors, such as climate or crop type. Because phosphonate is systemic and stable in plants, it should be applied infrequently in order to avoid accumulation problems. Plant species may differ in phosphonate uptake and translocation (Cooke and Little 2001), and individual P. infestans isolates show great variation in sensitivity (Bashan, Levy, and Cohen 1990; Coffey and Bower 1984) to phosphonate compounds, which may impact the effectiveness of phosphonate.
Synthesis of the Phosphoric Esters: ..
It has now been found that the yield and purity in the preparation of phosphoric acid alkyl propargyl esters and phosphoric acid aryl propargyl esters can be further increased if the synthesis is carried out as a two-phase reaction in thepresence of catalytic amounts of tertiary amines or quaternary ammonium or phosphonium salts with at least 9 C atoms, and an inorganic base in at least equimolar quantity is used as an acid-trapping agent.
Phosphoric acids and phosphates - Wikipedia
If a tertiary amine is used as the catalyst, this is preferably added to the batch to the extent of about 1 to 10 mol %, and about 0.01 to 1 mol % of quaternary ammonium or phosphonium salt suffices; the mol % in each case is relative tophosphoric acid ester chloride.