One‐Pot Synthesis of a 1,2‐Diphospholide by Double C–H Deprotonation

Abstract

Rapid testing of hydrophilic and hydrophobic basic immobilized amine sorbents (BIAS) for CO2 capture stability under practical conditions was achieved by direct contact of the sorbents with flowing liquid water. Losses in both CO2 capture capacity and amine content of sorbents after exposure to 0.5 mL min−1 of H2O at 25 °C for 40 min followed similar trends as losses observed after exposure to N2/steam (105 °C, 7 % H2O) for 10 h. We also found that hydrophobic TMPED helped stabilize sorbents to H2O, which was confirmed by DRIFTS and combined TGA‐DSC.

Synthesis of 1,2-Diphospholides Using a Main Group “Superbase”

“…The identity of 6 is further supported by 1 H NMR and 1 H– 31 P HMBC spectroscopic studies, which show that the proton resonance at δ = 10.30 (d, 3 J PH = 3.5 Hz) can be assigned to the C–H of the 5-membered ring of 6 . In our previously published work we showed that the reaction of n BuLi/As­(NMe 2 ) 3 with MesPH 2 gives the arsenic–phosphorus heterocycle 4,6-dimethylbenzo-1-arsa-2-phospholide, an arsenic analogue of antimony heterocycle 6 . The NMR spectroscopic characteristics of the [Li­(TMEDA) 2 ] + salt of the arsenic anion are similar to 6 , displaying a singlet resonance at δ = 175.7 ppm in the 31 P NMR spectrum and a singlet at δ = 9.01 in the 1 H NMR spectrum, for the C–H of the 5-membered ring.…”

“…The synthesis of compounds 2 – 4 was achieved according to Scheme (see the Experimental Section). Our previous studies of 1 , showed that this reaction involving C–H activation of the o -CH 2 groups occurs via a series of oligo-phosphorus intermediates …”

“…5% to 20%, from batch to batch. Our previous work on the mechanism of formation of anion 1 showed that the Sb 7 3– Zintl ion is formed concurrently with the diphospholide . The similar solubilities of the diphospholide salts and the antimony Zintl compound formed in the reaction (most likely Li­(TMEDA) 2 ] 3 {Sb 7 ]) − meant that washing and fractional crystallization were ineffective methods of purification.…”

“…[Li­(12-crown-4) 2 ]­[ 4 ] was crystallized by storage of a THF/toluene solution at room temperature, allowing the 9-methylbenzo-1,2-diphospholide ( 4 ) to be structurally characterized (Figure ). Comparison of the structural parameters for previously reported anion 1 with new anions 2 and 4 shows that the bond lengths and angles within their five-membered C 3 P 2 ring units are nearly identical within the crystallographic errors (Table ).…”

“…Recently, the synthesis of the 4,6-dimethyl-substituted diphospholide anion ( 1 ) (Figure c) was reported concurrently by the Hey-Hawkins group and us, using two different synthetic approaches. Our approach, which involves the one-pot reaction of MesPH 2 (Mes = 2,4,6-trimethylphenyl) with the redox-active superbase mixture n BuLi/Sb­(NMe 2 ) 3 , involves the in situ generation of the tetraphosphane-1,4-diide [MesP] 4 2– which then ring-closes by a combination of ortho -Me deprotonation and oxidation (Scheme a).…”