Gas/Solid Reactions with Acetone

Abstract

Anisotropic phase rebuilding I Waste preventionGadsolid reactions of acetone vapor with neutral organic compounds, salts, or host crystals with strict exclusion of solvents are reported. This gas/solid technique largely avoids waste formation and saves resources, Starting hydrochlorides or hydrobromides are also synthesized by gadsolid techniques. Dihydrohalides of o-phenylenediamines give 1,5-benzodiazepines 3, aromatic and aliphatic 1,2-aminothiols (oaminothiophenol, penicillamines, cysteine) yield five-membered thiazolines and thiazolidines 7, 9, 11, 13. Virtually all carbonyl reagents of the primary amino type 14 give quantitatively the imino derivatives 15 and water. Salt formation may be helpful for increasing melting points and sometimes reactivity as in 8, 10, and 12 if surface passivation has to be overcome. In the case of solid 14 the free bases react equally well. Acetone (2) may be quantitatively removed from exhaust gases by using hydroxylaminium phosphate with formation of free acetone oxime at high flow rates. Inclusion of acetone into various hosts (17-20, but not 16) is more efficient by imbibition from the gas phase than by crystallization from acetone as the solvent. This advantage may be utilized for gas separations. Some further gases (vapors) coexist in imbibed clathrates whereas others do not. The mechanisms of the gadsolid reactions are elucidated using atomic force microscopy (AFM). Phase rebuildings involve anisotropic movements of molecules over large distances and the formation of characteristic features. In some cases surface hydrates catalyze the gadsolid reaction. Solid-state mechanisms for imbibition from the gas phase into host crystals with formation of clathrates are similar in nature to those of the covalent reactions. These results are correlated with known X-ray crystal structures where available.

Organic Solid-State Reactions

“…Several later performed so-called green repetitions of this reaction under less suitable different conditions (not citing Ref. [47]) did reach neither quantitative yields nor similar scaling possibilities.…”

“…Changes in crystal structure upon clathration are clearly seen by AFM measurement revealing molecular migrations that are strictly related to the initial crystal structures in the phase rebuilding stage (cf., for example, Ref. [47]). Other signs are phase transition into product followed by crystal disintegration (detachment) with increase in specific surface and density change.…”

“…Selectivities, complete uptakes at 20-25 ∘ C or in flow systems at 0 ∘ C and sharp desorption ranges (as detected by DSC/TGA) are received. Interestingly, the host 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol imbibes acetone to a 1 : 2 host/guest ratio [44,47]. Multiple guests can coimbibe into a given host [47] (e.g., acetone and t-butylether into 1,1-bis-4-hydroxyphenylcyclohexane) [44,47].…”

“…Several solid amino acids add quantitatively gaseous HCl at room temperature, but glycine and alanine that were previously exposed to ambient air exhibit a passivating surface and require therefore short premilling. (l)-Histidine adds 2HCl to generate the dihydrochloride [31,47]. Even very weak bases such as 1-methyl-benzotriazole (room temperature) or benzothiazoles (low temperatures) form the hydrohalides quantitatively at the complete absence of moisture [63].…”

“…An intramolecular cyclizing "linear dimerization" is the key step in the benzodiazepine gas-solid synthesis from o-phenylenediamine dihydrochlorides and acetone vapor via the bisiminium salt [47]. The yield is quantitative at the 1 g or 30 g scale at room temperature (only 71% yield at the R = H, R ′ = NO 2 system).…”