Industrial Upscaling of DOPO-Based Phosphonamidates and Phosphonates Derivatives Using Cl₂ Gas as a Chlorinating Agent

Abstract

Herein, we report the industrial synthesis procedure of phosphonamidate and phosphonate derivatives via an efficient and simple chlorination of 9,10-dihydro-9-oxa-10-phospha­phenanthren-10-oxide (DOPO) with Cl2 gas. The key step in the synthesis is the conversion of the P–H bond to P–Cl of DOPO by flowing Cl2 gas into a solution of DOPO in dichloromethane, affording the key intermediate 9,10-dihydro-9-oxa-10-phospha­phenanthrene-10-chloride (DOPO-Cl) compound which is industrially not available. DOPO-Cl was isolated, characterized, and used for this synthesis of DOPO-based phosphonamidates and phosphonates in relatively high yield by reaction with the corresponding amines and alcohols, respectively. The experimental results show that the chlorination reaction occurs in equimolar ratios of Cl2 gas to DOPO compound. Subsequently, the procedure developed in laboratory scale was industrially applied for synthesis of the 6,6′-(ethane-1,2-diylbis­(azanediyl))­bis­(dibenzo­[c,e]­[1,2]­oxaphos­phinine-6-oxide) (EDA-DOPO) compound and 6-((1-oxido-2,6,7-trioxa-1-phospha­bicyclo­[2.2.2]­octan-4-yl)­methoxy)­dibenzo­[c,e]­[1,2]­oxa­phosphinine-6-oxide (DOPO-PEPA). All synthetic compounds thus obtainedwere characterized and found to be identical to the authentic laboratory scale products.

Synthesis of Trispirocyclotriphosphazenes with Oxaphosphorine Rings and Their Crystal and Molecular Structures

“…First, fully dried DOPO was derivatized to DOPO-Cl using chlorine gas as a chlorinating agent, as depicted in Scheme . DOPO was reacted with chlorine gas at 40 °C for 5 h in anhydrous dichloromethane as the solvent according to the method described in the literature . After the reaction, the reactant was concentrated to quantitatively give DOPO-Cl as a white solid.…”

Recent developments in P(O/S)–N containing flame retardants

“…Hydroxyl containing spirocyclic phosphoramidate 80 (Figure 22) was prepared by reacting neopentyl glycol with POCl 3 in acetone, followed by dropwise addition of DEA and TEA in acetone at 0-5 C. 122 Cotton fabrics were treated with various concentrations (10,15,20,25, and 30%) of Compound 80 in acetone/water (1:4 v/v) solutions. The treated fabrics passed the vertical burning tests and achieved higher LOI values (27.0-29.3%), respectively, compared with neat cotton (19%).…”

“…In addition, reactive FRs require careful formulation of various ingredients, whereas nonreactive FR additives could be used in various polymer matrices without much modification. 19,20 The use of phosphorus-nitrogen (P-N) compounds as FRs are extensively studied, and their FR effect in many cases is attributed to P-N synergism. 12 Such interactions lead to the reduction of the load of FRs in the material and improved FR efficacy.…”

“…[13][14][15][16][17][18] More recently, DOPO-based phosphonamidate (6,6'-(ethane-1,2-diylbis(azanediyl))bis(dibenzo [c,e][1,2]oxaphosphinine 6-oxide) [EDA-DOPO]) has been shown to be nontoxic and successfully upscaled in the industry. 19,20 The use of phosphorus-nitrogen (P-N) compounds as FRs are extensively studied, and their FR effect in many cases is attributed to P-N synergism. It is believed that P-N synergism encourages the crosslinking of polymeric chains during the thermal decomposition process.…”

Enhanced PET processing with organophosphorus additive: Flame retardant products with added-value for recycling

“…PET was prepared and provided by Serge Ferrari Tersuisse AG (Emmenbrücke, Switzerland) with a M w ≈ 124 kg•mol -1 as measured by gel permeation chromatography (GPC). DP was synthesized according to a novel and sustainable protocol described in details elsewhere [59].…”