General description

N,N-Diethylhydroxylamine is used as a high-efficiency polymerization inhibitor for vinyl monomers and conjugated olefins, a terminator for styrene-butadiene emulsion polymerization, and an antioxidant for unsaturated oils.

Fig. 1 The structure of N,N-Diethylhydroxylamine.

Physicochemical property

N,N-Diethylhydroxylamine is a colorless and transparent liquid with a boiling point of 125-130 °C and an ammonia odor. It is easily soluble in water, soluble in ethanol, ether, chloroform and benzene.

Synthetic routes

Fig. 2 The synthetic method 1 of N,N-Diethylhydroxylamine.

Mix purified triethylamine (6.3 mL, 4.3 mmol) and hydrogen peroxide (10 mL, 0.1 mol, 30%) with water. Add the mixture into each steel alloy (Fe-Cr-Ni alloy, GB-1220-92) autoclave with a filling capacity of 90% (1.4 MPa). Seal the autoclaves tightly. Place in the oven with the temperature ranging from 20 °C to 120 °C at intervals of 20 °C. After 5 days, take out the solution in the autoclaves and analyze. Employ gas chromatography-mass spectroscopy (GC-MS) to identify the products. Observe 120 °C as a turning point [1].

Fig. 3 The synthetic method 2 of N,N-Diethylhydroxylamine.

Dissolve substituted piperidin (1 equivalent) in MeOH (0.5M). Treat the mixture with K₂CO₃ (2.0 equivalents). Stir the mixture for 3 hours. Remove the MeOH under vacuum. Dilute the mixture with H₂O and EtOAc. Separate the layers. Extract the aqueous layer with EtOAc (× 3). Dry the combined organic layers over MgSO₄. Filter the combined organic layers. Evaporate the combined organic layers [2].

Application

Salt-free reducing reagent

N, N-diethylhydroxylamine (DEHA) is a novel salt-free reducing reagent used in the separation of Pu and Np from U in the treatment of used nuclear fuel. This paper reports on the radiation damage and radiolytic by-product of 0.5 mol^.L^-1 DEHA in 0.3 mol^.L^-1 similar to 1.0 mol^.L^-1 HNO₃ at dose up to 25 kGy. Results show that the radiolysis rate of DEHA is less than 10%. The main radiolytic products are hydrogen, acetaldehyde, acetic acid and nitrous acid, which increase with the dose. The concentration of acetaldehyde and acetic acid is much higher than that of nitrous acid [3].

Cascade extraction of uranium and cascade extraction-separation of uranium/neptunium and uranium/plutonium with 6 extraction stages and 6 stripping stages have been studied in the presence of N,N-diethylhydroxylamine (abbreviated as DEHAN) in nitric acid medium according to the experimental conditions of the purification cycle of uranium (referred to as contactor 2D) of the second cycle of the Purex Process. The percent recovery and material balance of U(VI) were found to be 99.997% and 101.5%, respectively. The decontamination factors and material balances of neptunium and plutonium from uranium were found to be 32.4, 25.3 and 102.5%, 105.7%, respectively. It suggests that the simultaneous separation of neptunium and plutonium from uranium is technically feasible for contactor 2D using N,N-diethylhydroxylamine as a salt-free reductant [4].

Nanosecond pulse radiolysis

The reaction mechanisms and rate constants of N, N-diethylhydroxylamine (DEHA) with ·OH, CO₃^?·, e_aq^? and ·H were studied. Results show that ·OH radicals oxidize DEHA by hydrogen abstraction from DEHA's hydroxyl group to form transient (C₂H₅)₂NO·, which has an absorption maximum at 395 nm. The transient intermediates for the reactions of DEHA with CO₃^?· and e_aq^?, as well as protonated DEHA with ·H, show no absorption peak between 300 and 800 nm. The rate constants for the reactions of DEHA with ·OH, CO₃^?· and e_aq^?, also protonated DEHA with ·H, were measured. [5].

Gaseous products generated by radiation degradation

Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA) in aqueous solution are studied. The results show that by 10 similar to 1000 kGy irradiation of the solution in DEHA concentration of 0.1 similar to 0.5 mol^.L^-1, the gaseous products were mainly hydrogen, methane, ethane and ethene. The volume fraction of hydrogen did not change much with different concentrations of DEHA. The volume fraction of methane and ethane decreased, but that of ethene increased, with increasing DEHA concentration. The volume fraction of hydrogen, methane and ethane increased with the dose. The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration [6].

References

[1] Bai X, Liu Z, Ye K, et al. The oxidation of the alpha-carbon of amines in hydrothermal condition: an alternative synthetic route of compounds containing amide bond[J]. Tetrahedron Letters, 2014, 55(2): 319-321.

[2] Svejstrup T D, Ruffoni A, Juliá F, et al. Synthesis of arylamines via aminium radicals[J]. Angewandte Chemie International Edition, 2017, 56(47): 14948-14952.

[3] Wang J H, Chen Y, Wan Y, et al. Radiolysis and radiolytic by-product of N, N-diethylhydroxylamine in HNO3 at lower dose[J]. Journal of Radioanalytical and Nuclear Chemistry, 2022: 1-8.

[4] Anyun Z, Jingxin H, Xianye Z, et al. Hydroxylamine derivative in PUREX process. VI. Study on the partition of uranium/neptunium and uranium/plutonium with N, N-diethylhydroxylamine in the purification cycle of uranium contactor[J]. Solvent Extraction and Ion Exchange, 2001, 19(6): 965-979.

[5] Wang J H, Zhao X Y, Shi Y, et al. Nanosecond pulse radiolysis of aqueous N, N-diethylhydroxylamine solution[J]. Journal of Radioanalytical and Nuclear Chemistry, 2022, 331(1): 241-247.

[6] Jinhua W, Shengxiu W, Borong B A O, et al. Gaseous products generated by radiation degradation of N, N-diethylhydroxylamine aqueous solution[J]. Nuclear Science and Techniques, 2008, 19(2): 79-82.