337. Infrared absorption spectra of some urea complexes

Barlow, George; Corish, Patrick J.

doi:10.1039/jr9590001706

Cited by 25 publications

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“…Although the difference in channel diameter between thiourea and selenourea inclusion compounds is small, selenourea seems to be much more selective in its choice of guest molecules (Takemota & Sonoda, 1984). There are more striking differences in the unit-cell dimensions of the selenourea inclusion compounds than are observed for the thiourea inclusion compounds, as adaptation of the selenourea lattice to the shape and size of the included molecules is apparently relatively easy (Nicolaides & Laves, 1958;Barlow & Corish, 1959;Casu, 1961). A theoretical study of the conformat~,ons and vibrational frequencies in urea, thiourea and selenourea compounds has been reported (Ha & Puebla, 1994).…”

Section: Introductionmentioning

confidence: 99%

New Inclusion Compounds of Selenourea with Tetraethyl- and Tetra-n-propylammonium Halides

Mak²

1997

Acta Crystallogr Sect B

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Air-sensitive selenourea inclusion complexes tetraethylammonium chloride–selenourea (1/2), (C2H5)4N+.C1−.2[(NH2)2CSe] (1), tetra-n-propyl-ammonium chloride–selenourea (1/3), (n-C3H7)4N+.C1−.3[(NH2)2CSe] (2), tetra-n-propylammonium bromide–selenourea (1/3), (n-C3H7)4N+.Br−.3[(NH2)2CSe] (3), and tetra-n-propylammonium iodide–selenourea (1/1), (n-C3H7)4N+.I−.(NH2)2CSe (4), have been prepared and characterized by X-ray crystallography. Crystal data, Mo Kα radiation: (1), space group P21/n, Z = 4, a = 8.768 (5), b = 11.036 (6), c = 19.79 (1) Å, β = 96.92 (1)°, R F = 0.055 for 1468 observed data; (2), space group Cc, Z = 4, a = 18.091 (4), b = 13.719 (3), c = 11.539 (2) Å, β = 111.93 (3)°, R F = 0.051 for 1187 observed data; (3), space group Cc, Z = 4, a = 18.309 (4), b = 13.807 (3), c = 11.577 (2) Å, β = 112.45 (3)°, R F = 0.049 for 1592 observed data; (4), space group P21/n, Z = 4, a = 8.976 (1), b = 14.455 (2), c = 15.377 (3) Å, β = 94.16(1)°, R F = 0.062 for 1984 observed data. In the crystal structure of (1) the parallel alternate arrangement of selenourea–chloride ribbons and selenourea chains generates a puckered layer and the cations are sandwiched between them. In the isomorphous complexes (2) and (3) wide selenourea–halide double ribbons are crosslinked by bridging selenourea molecules via N—H...Se and N—H...X hydrogen bonds [average N...Se = 3.521 (8) and 3.527 (7), N...Cl = 3.354 (8) and N...Br = 3.500 (7) Å in (2) and (3), respectively] to form a channel-like three-dimensional network and the cations are accommodated in a single column within each channel. In the crystal structure of (4) the selenourea molecules are joined in the shoulder-to-shoulder fashion via N—H...Se hydrogen bonds [N...Se = 3.529 (7) and 3.534 (7) Å] to generate a ribbon and each selenourea molecule also forms a pair of chelating N—H...I hydrogen bonds [N...I = 3.567 (7) and 3.652 (7) Å] to an adjacent iodide ion.

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Section: Introductionmentioning

confidence: 99%

New Inclusion Compounds of Selenourea with Tetraethyl- and Tetra-n-propylammonium Halides

Mak²

1997

Acta Crystallogr Sect B

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“…Precisely, the IR bands seen at 1455 cm obtained by [54]. According to the predictions made by [55,57], the vibrations occurring at 786 cm −1 were ascribed to mutual N-H and CO out-of-plane wagging vibrations or in other words it is called the skeletal out-of-phase bending frequency equally attributable to larger deformational force constant, resulting from the decrease in the N-N distance of tetragonal urea [53]. Finally, for the KPDMU, the infrared bands occurring at 739 cm −1 represent the characteristic hydroxyl stretching vibrations of alumina of the kaolinite in a tetrahedral configuration for the AlO 4 antisymmetric stretching while the SiOAl skeletal vibrations are observed at 527 cm −1 .…”

Section: Ft-irmentioning

confidence: 99%

Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

Sempeho¹,

Kim²,

Mubofu³

et al. 2015

Journal of Chemistry

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Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU). Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600 ∘ C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

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“…X-Ray st~iclies (I) have revealed the general details of the structures of h~~drocarbon-urea adducts. There have also bee11 infrared studies (2,3,4) which have supplemented this structural inforination. The results available show that ~irhereas pure urea crystallizes with a tetragonal structure, when it forms a n adcluct it adopts a hexagonal crystal structure.…”

Section: Introductionmentioning

confidence: 99%

The Infrared Absorption Spectra of Urea–hydrocarbon Adducts

Fischer¹,

McDowell²

1960

Can. J. Chem.

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T h e i~lfra~-ecl absorption spectra of the aclcl~~cts formed bct\\feen urea ancl hydrocarbons from 72-heptanc to rc-l~exatlccane have been measurcd ill the range 600 cm-I t o 4000 cm-I. From a consideration of the crystal symmetries of urea ancl the urea-hydrocarbon adducts it has been possible t o assig~l the various vibration frequencies. The band shifts observctl arc explained i l l terms of chonge2; in bond lengths and bond angles. INTRODUCTIONUrea fornls aclclucts, or clathrates, with a variety of organic illolecules such as hycli-ocarbons, esters, and 01-ganosilanes. X-Ray st~iclies (I) have revealed the general details of the structures of h~~drocarbon-urea adducts. There have also bee11 infrared studies (2, 3, 4) which have supplemented this structural inforination. The results available show that ~irhereas pure urea crystallizes with a tetragonal structure, when it forms a n adcluct it adopts a hexagonal crystal structure. I11 this way long channels are forizzecl \vhich allow the enclathrated hydrocarbon, or other molecule, to be located inside a cage of urea ' I 1011 illolecules helcl together by hydrogen bonds. Until quite recently little inform, t ' was available concer~~ing the physical state of the enclathrated hydrocarbon.in these urea-hydrocarboi~ adducts. Kuclear magnetic resonance studies i l l these laboratories (5) have show11 that the eilclathrated hydrocarboiI ~nolecules have some vibrational a i d rotational, or torsional, freedom within the urea channels. \A7e here report studies of the infrared absorptions spectra of a series of urea-hydrocarbon complexes. ?'he aim of this work is to obtain informntion on the molecular motions of the trapped hyclrocarbons, the stabilities of the conzplexes, and tlze structure of the hexagonal form of urea.Apart from worli by Stuart (2), \\rho st~iclied the N-13 stretching frecluencies of the urea-cetane nclduct, and by Barlow and Corish (4) on the sitme adduct ( a n l o~~g other classes of adducts), 110 other investigatioizs of the llomologous I~ydrocarbon-urea adducts seeill to have been undertaken. EXPERIMENTALThe preparation of the adducts was accoillplished by t\vo different methods. ( a ) 1.23 g of A. R. grade urea (recrystallized), very finely powdered, was shalien with 15 ml of the respective hydrocarbon (Phillips, research grade) for periods ranging from 12 to 48 hours. Decantation, vacuum filtration for 30 seconds, ancl drying in filter paper gave a finely crystalline procluct. (b) :EOO mg of hydrocarbon were placed in a vial with 10 1111 of saturated urea-methanol solution and brought t o boil. Cooling of the stoppered vial i11 a \veil-insulated Dewar flasli yielded hexagonal crystals up to 35 nzin in length.The spectroscopic iiieasure~nents were carried out on a Perkin-Elmer infrared spectrophotometer, moclel 21. The crystalline hydrocarbon-urea adducts were exanlined either by the potassium l~r o n~i d e disk method, or as Nujol and hexaclzlorobutadiene mulls.ldIant~script rcccivcd Scptenzber 8, 1969. Contribution from the

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337. Infrared absorption spectra of some urea complexes

Cited by 25 publications

References 0 publications

New Inclusion Compounds of Selenourea with Tetraethyl- and Tetra-n-propylammonium Halides

New Inclusion Compounds of Selenourea with Tetraethyl- and Tetra-n-propylammonium Halides

Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

The Infrared Absorption Spectra of Urea–hydrocarbon Adducts

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