One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

Abstract

Dialkyl hexane-1,6-dicarbamate was synthesized, for the first time, by a one-pot reaction of 1,6-hexanediamine (HDA), urea, and alcohols, including methanol, ethanol, propanol, and butanol, in a self-designed batch reactor, using zinc-incorporated berlinite (ZnAlPO 4 ) as a catalyst. The yield of dibutyl hexane-1,6-dicarbamate (2) was systematically investigated as a function of Zn/Al molar ratio, reaction temperature, reaction time, catalyst usage and urea/HDA/butanol molar ratio. Based on these studies, the optimized reaction conditions were as follows: molar ratio urea/HDA/ butanol = 2.6:1:8.6, catalyst usage = 3.0 g, reaction temperature = 493 K, reaction time = 6 h and reaction pressure = 1.2 MPa; a yield of 2 of 89.7% was achieved over the ZnAlPO 4 (molar ratio Zn/Al = 0.04) catalyst. The catalysts were characterized by X-ray photoelectric spectroscopy (XPS) and scanning electron microscope (SEM). Additionally, based on these experimental results, it was also proposed that the catalysis recycle of the one-pot synthesis of 2 from urea, HDA, and butanol over the ZnAlPO 4 catalyst.

Synthesis and Characterization of Graphene Oxide Derivatives via Functionalization Reaction with Hexamethylene Diisocyanate

“…Thus, it turns out to be quite difficult to establish a reaction mechanism and a kinetic model. The reactivity of isocyanate vs. different functional groups follows the order: Primary amine > secondary amine > hydroxyl > acid > anhydride > epoxide [ 24 ]. The reaction between an alcohol and an isocyanate group to form a carbamate ester is moderate, hence is usually catalyzed by bases, mainly tertiary amines like TEA [ 25 ].…”

“…The reaction is exothermic and is also catalyzed by tertiary amines. It has been demonstrated that the isocyanate reactivity with water and primary hydroxyl group is comparable, and more than double that with carboxylic acids [ 24 ]. Isocyanates also react with amines to give ureas.…”

“…Regarding the reaction carried out for 48 h (HDI-GO 3), a slight fall in FD is found ( Table 2 , entry 4) compared to the initial trial. Lu et al [ 24 ] reported that the conversion yield of the reaction between an isocyanate and an alcohol crosses over at longer reaction times, suggesting partial reversibility and equilibrium. Similarly, Sato [ 31 ] found that at high concentrations of both reactants, the reaction rate decreased rapidly with increasing reaction time.…”

Sustainable Jatropha Oil-Based Membrane with Graphene Oxide for Potential Application in Cu(II) Ion Removal from Aqueous Solution

“…Apparently, isocyanate was prompted to have reaction with the functional groups of GO as side reaction, whether from the edge carboxylic acid, surface hydroxyl, or epoxide in producing amides or carbamate esters [57]. As stated by Sun et al [58], the sequence of isocyanate reactivity with different functional group was in the sequence as primary amine > secondary amine > hydroxyl > acid > anhydride > epoxide. Due to the reactivity of isocyanate versus different functional group, isocyanate had higher reactivity with the hydroxyl group compared to the other functional group of GO.…”

An Escape from Noble Metals for Generating Urethanes via Reductive Carbonylation of Nitroarenes over FeSe2/γ-Al2O3 †

“…Conventionally, the production of urethanes involves the employment of phosgene, which is extremely toxic and harmful to the environment and human beings. Therefore, there have been tons of endeavors for producing carbamates via phosgene-free pathways [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Among them, the catalytic reductive carbonylation of nitroarenes is regarded as one of the promising routes [6][7][8][20][21][22][23][24][25][26][27].…”