Die Harnstoff‐Addition der aliphatischen Verbindungen

Schlenk, W.

doi:10.1002/jlac.19495650205

Cited by 193 publications

(58 citation statements)

References 4 publications

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“…Similar quantitative data have been obtained on fatty acids (37), hydrocarbons (64, 867, halides, mercaptans, ketones, and other classes of organic compounds (62,64).…”

Section: Decompositionsupporting

confidence: 68%

Urea and Thiourea Complexes in Separating Organic Compounds

Swern¹

1955

Ind. Eng. Chem.

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“…Similar quantitative data have been obtained on fatty acids (37), hydrocarbons (64, 867, halides, mercaptans, ketones, and other classes of organic compounds (62,64).…”

Section: Decompositionsupporting

confidence: 68%

Urea and Thiourea Complexes in Separating Organic Compounds

Swern¹

1955

Ind. Eng. Chem.

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“…4,17,19) Inclusion compounds vary widely depending on the guest. 7,[24][25][26] Studies on urea inclusion compounds have focused on inclusion compounds formed by linear hydrocarbons and their derivatives such as long-chain alcohols, 17,18,27,28) for example, the urea-cetyl alcohol inclusion compounds reported in 1979, 19) and urea-stearic acid and urea-palmitic acid inclusion compounds reported in 1996 and 1997, repectively. 17,18) The DSC, PXRD and PXRD-DSC results obtained here are discussed in reference to these earlier reports.…”

Section: Discussionmentioning

confidence: 99%

Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 1): Rate of Crystallization from Cream Containing 20% (w/w) Urea and Evaluation of the Properties of the Deposit

Goto

Morita

Terada

2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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Two creams containing 20% (w/w) urea and various emulsifiers, a nonionic surfactant (NS) and lecithin (LEC), were prepared, and the rate of crystallization following application of the cream and differences in the properties of the deposits were investigated. Post-application crystallization was slower with the LEC formulation. Differences in the crystals obtained from the two formulations and from a 20% aqueous solution of urea were evaluated by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), powder X-ray-DSC (PXRD-DSC) and Fourier transform infrared spectrophotometry (FT-IR). PXRD and PXRD-DSC measurements showed that the diffraction patterns of both formulations differed from that of urea. The NS formulation provided diffraction peaks for urea and a urea composite, whereas only the urea composite was evident in the LEC formulation. DSC scans of urea showed an endotherm at around 134°C, whereas the deposits from both formulations provided an endotherm 23-25°C below that of urea; the NS formulation also showed a peak at around 140°C. These results indicate a tendency for urea crystallization in the NS formulation. FT-IR measurements showed that both deposits have a urea-based structure. The effects of the LEC formulation components on the physical properties of urea were investigated by PXRD and showed that all diffraction peaks were evenly weakened, suggesting that urea tends to be amorphous and that the formulation impacts post-application urea crystallization. Consequently, the amorphous state of urea can be maintained post-application by optimizing the formulation, thereby increasing the clinical efficacy of the cream.

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“…Data processing of the experimental (from the CXP 300 NMR spectrometer) and theoretical 2 H NMR signals were done on a SUN workstation by using NMR1 and Sybyl/Triad software packages (Tripos, St. Louis, MO, USA). The data from 1 H MAS and 13 C CP/MAS NMR measurements were handled by utilizing the MestRec software.…”

Section: Data Processing and Simulationsmentioning

confidence: 99%

The structural and dynamic properties of 1‐bromodecane in urea inclusion compounds investigated by solid‐state ¹H, ¹³C and ²H NMR spectroscopy

Yang¹,

Müller²

2011

Magnetic Reson in Chemistry

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For asymmetric guest molecules in urea, the end-groups of two adjacent guest molecules may arrange in three different ways: head-head, head-tail and tail-tail. Solid-state (1)H and (13)C NMR spectroscopy is used to study the structural properties of 1-bromodecane in urea. It is found that the end groups of the guest molecules are randomly arranged. The dynamic characteristics of 1-bromodecane in urea inclusion compounds are probed by variable-temperature solid-state (2)H NMR spectroscopy (line shapes, spin-spin relaxation: T2 , spin-lattice relaxation: T1Z and T1Q) between 120 K and room temperature. The comparison between the simulation and experimental data shows that the dynamic properties of the guest molecules can be described in a quantitative way using a non-degenerate three-site jump process in the low-temperature phase and a degenerate three-site jump in the high-temperature phase, in combination with the small-angle wobbling motion. The kinetic parameters can be derived from the simulation.

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Die Harnstoff‐Addition der aliphatischen Verbindungen

Abstract: Vor etwa 10 Jahren machte M. P. Bengen

Cited by 193 publications

References 4 publications

Urea and Thiourea Complexes in Separating Organic Compounds

Urea and Thiourea Complexes in Separating Organic Compounds

Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 1): Rate of Crystallization from Cream Containing 20% (w/w) Urea and Evaluation of the Properties of the Deposit

The structural and dynamic properties of 1‐bromodecane in urea inclusion compounds investigated by solid‐state ¹H, ¹³C and ²H NMR spectroscopy

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Die Harnstoff‐Addition der aliphatischen Verbindungen

Abstract: Vor etwa 10 Jahren machte M. P. Bengen

Cited by 193 publications

References 4 publications

Urea and Thiourea Complexes in Separating Organic Compounds

Urea and Thiourea Complexes in Separating Organic Compounds

Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 1): Rate of Crystallization from Cream Containing 20% (w/w) Urea and Evaluation of the Properties of the Deposit

The structural and dynamic properties of 1‐bromodecane in urea inclusion compounds investigated by solid‐state 1H, 13C and 2H NMR spectroscopy

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The structural and dynamic properties of 1‐bromodecane in urea inclusion compounds investigated by solid‐state ¹H, ¹³C and ²H NMR spectroscopy