Synthesis of (pyrrolidin-1-yl- and morpholinoalkyl)phosphonic acids

Abstract

A fragment of phosphonous acid combined with an aminoalkyl group underlies the structure of a series of organic compounds endowed with a high biological activity without high toxicity, and also anticorrosion properties with respect to carbon and low-alloy steels [1][2][3][4].Convenient synthons for introduction of this fragment are phosphonic acid and its esters whose aminoalkylation provided a wide series of nitrogen-containing phosphonous acids, also with nitrogen heterocyclic substituents involved into the composition of the amino component in the condensation reaction and linked to the reacting primary amino group through an amino-hydrocarbon bridge [5]. Although in patent [5] in the general claim was declared a possibility to synthesize N-heterylalkylphos-phonic acids where the heterocyclic nitrogen is linked to the phosphonic group through a single-carbon bridge (at m = 0), these compounds, e.g., with a pyrrolidine or morpholine fragments were not described in the given examples, and their properties were not characterized. Moreover the reactivity of secondary alicyclic amines can considerably differ from that of primarily linear ana-logs. It is known that the appearance of steric hindrances at the secondary nitrogen in the amine component considerably reduces its reactivity and the acid properties of the resulting aminoalkylphosphonic acids [6].Ht(CH 2 CH 2 NH n ) m [CR 1 R 2 P=O(OH) 2 ] p Mannich reaction using formaldehyde, acetone, or methyl ethyl ketone as carbonyl component. n = 0, 1; m = 0-3; p = 1, 2.In this study we perfomed the aminoalkylation of phosphonic acid with pyrrolidine and morpholine along R 1 = R 2 = H (a), CH 3 (b); R 1 = CH 3 , R 2 = C 2 H 5 (c); No X (I, III), X = O (II, IV).It turned out that at employing the mentioned amines the plausible yields (50-85%) of the target products were attained only at a prolonged heating of the reaction mixture for 10-12 h.The synthesized compounds IIIa-IIIc, IVa, and IVb are lightly colored oily substances, well soluble in water and poorly soluble in organic solvents. Like all known aminoalkylphosphonic acids [6, 7] the obtained compounds exist in solution in zwitter-ionic betaine-like structure A.This fact is confirmed by the downfield shift by 0.2-0.5 ppm of the signals of methylene protons in the 1 H NMR spectra as compared to the analogous signals

Synthesis of Cerium N-Morpholinomethylphosphonic Acid and Its Flame Retardant Application in High Density Polyethylene

“…As is known to all, the catalyst in an appropriate addition range could exert good catalytic effect in a certain system. Exceeding the amount of catalyst will show no improvements or even worsen the catalytic effect, which can be seen as the same phenomenon in Cao’s research …”

“…N -Morpholinomethylphosphonic acid (MMPA) was synthesized by using a modified Mannich reaction . The synthetic route is illustrated in Scheme (a).…”

“…Recently, our research group reported a novel metal IFR compound (Zn-TEPAPM), which contains the IFR structure and transition metal ions (zinc) in one molecular. The results show that such designation of an organic–inorganic compound could solve the above problem and can improve the flame retardancy of polyethylene (PE).…”

1,3,2-Diazaphospholidine (N-Heterocyclic Phosphine)-Mediated Carbon–Phosphorus Bond-Forming, One-Pot Tandem Reaction: A Route to α-Amino Phosphonates

“…The dialkyl phosphonates are activated by Lewis acids, molecular sieves, or magnetic nanoparticles to generate the nucleophilic dialkyl phosphites, which then rapidly react with iminium intermediates to ultimately construct the tertiary α-amino phosphonates (Scheme a). Brønsted acid-catalyzed reaction with dialkyl phosphonates (Scheme a) and Lewis acid-mediated transformation involving trialkyl phosphites (Scheme b) are important alternative routes for the synthesis of tertiary α-amino phosphonates. Despite the great efforts devoted to the synthesis of biologically significant cyclic tertiary α-amino phosphonates, there are limitations such as the use of toxic metals, low product yields with especially cyclic secondary amines, and harsh reaction conditions (elevated temperatures and basic conditions).…”