The potency of hydrothermally prepared sulfated silica (SO4/SiO2) as a heterogeneous acid catalyst for ethanol dehydration into diethyl ether

The dehydration of ethanol into diethyl ether over a SO4/SiO2 catalyst was investigated. The SO4/SiO2 catalysts were prepared by the sulfation method using 1, 2, and 3 M of sulfuric acid (SS1, SS2, and SS3) via hydrothermal treatment. This study is focused on the synthesis of a SO4/SiO2 catalyst with high total acidity that can be subsequently utilized to convert ethanol into diethyl ether. The total acidity test revealed that the sulfation process increased the total acidity of SiO2. The SS2 catalyst (with 2 M sulfuric acid) displayed the highest total acidity of 7.77 mmol/g, whereas the SiO2 total acidity was only 0.11 mmol/g. Meanwhile, the SS3 catalyst (with 3 M sulfuric acid) has a lower total acidity of 7.09 mmol/g due to the distribution of sulfate groups on the surface having reached its optimum condition. The crystallinity and structure of the SS2 catalyst were not affected by the hydrothermal treatment or the sulfate process on silica. Furthermore, The SS2 catalyst characteristics in the presence of sulfate lead to a flaky surface in the morphology and non-uniform particle size. In addition, the surface area and pore volume of the SS2 catalyst decreased (482.56-172.26 m2/g) and (0.297-0.253 cc/g), respectively, because of the presence of sulfate on the silica surface. The SS2 catalyst's pore shape information explains the formation of non-uniform pore sizes and shapes. Finally, the activity and selectivity of SO4/SiO2 catalysts in the conversion of ethanol to diethyl ether yielded the highest ethanol conversion of 70.01% and diethyl ether product of 9.05% from the SS2 catalyst (the catalyst with the highest total acidity). Variations in temperature reaction conditions (175-225 °C) show an optimum reaction temperature to produce diethyl ether at 200 °C (11.36%).

Photocatalytic degradation of naphthol blue from Batik waste using functionalized TiO2-based composites

This work provides a first-time comparative study examining the photocatalytic activity of functionalized TiO₂-based composites to eliminate naphthol blue in Batik wastewater. Reduced graphene oxide (RGO) was synthesized by oxidizing solid graphite using the Hummers' method followed by sonication and reduction. N-doped TiO₂ (N-TiO₂) was synthesized from titanium tetrachloride (TiCl₄) and urea (CH₄N₂O) precursors by the sol-gel method. N-TiO₂ modified RGO (RGO/NT) was synthesized using a hydrothermal method from N-TiO₂ and RGO. Prepared TiO₂-based composites and commercial TiO₂, for comparison were characterized using Fourier transform infrared spectrometer (FTIR), X-Ray diffractometer (XRD), scanning electron microscope-energy dispersive X-ray (SEM-EDX), and UV-Vis diffuse reflectance spectrometer (UV-Vis DRS). FTIR characterization indicated Ti-N bonding in N-TiO₂ and RGO/NT. XRD patterns showed that commercial TiO₂ had a rutile phase, while N-TiO₂ and RGO/NT had an anatase phase with crystal sizes of 30.09, 16.28, and 12.02 nm, respectively. SEM results displayed the presence of small and glossy white N-TiO₂ dispersed on the surface of RGO. Characterization using UV-Vis DRS showed that the band gap energy values for TiO₂, N-TiO₂, and RGO/NT were 3.25, 3.12, and 3.08 eV with absorption regions at the wavelengths of 382, 398, and 403 nm, respectively. The highest photocatalytic activity for RGO/NT for degrading naphthol blue was obtained at pH 5, with a photocatalyst mass of 60 mg, and an irradation of 15 min. Photocatalytic degradation by RGO/NT on Batik wastewater under visible light showed higher effectivity than under UV light.

Dehydration Isopropyl Alcohol to Diisopropyl Ether over Molybdenum Phosphide Pillared Bentonite

Emissions from gasoline are one of the contributors to air pollution. Diisopropyl ether (DIPE) is an alternative oxygenate additive that can improve gasoline quality, minimizing CO and hydrocarbon gas emissions during combustion. However, there are very few studies on the use of pillared bentonite-based catalysts for DIPE production. This study aims to produce DIPE via dehydration of isopropyl alcohol using a molybdenum phosphide pillared bentonite (MoP-Bentonite) catalyst. The effect of Mo6+ metal concentration on the catalytic activity of isopropyl alcohol dehydration was also investigated. The catalyst that gives the highest DIPE yield will be analyzed by X-ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), Gas Sorption Analyzer (GSA), and total acidity using the gravimetric method. In addition, the dehydration product will be analyzed by Gas Chromatography-Mass Spectroscopy (GC-MS). The results showed that MoP has been successfully pillared into bentonite and showed an increase in surface area, acidity, and catalytic activity. The highest yield of DIPE was obtained using a 4 mEq/g MoP-Bentonite catalyst with a DIPE yield of 64.5%.

Hydrocracking optimization of palm oil to bio-gasoline and bio-aviation fuels using molybdenum nitride-bentonite catalyst

In this study, molybdenum nitride-bentonite was successfully employed for the reaction of hydrocracking of palm oil to produce a bio-gasoline and bio-aviation fuel. The prepared catalyst was characterized using XRD, FT-IR, and SEM-EDX. The acidity of the catalyst was determined using the pyridine gravimetric method. The result showed that the acidity of bentonite was increased after modification using molybdenum nitride. The hydrocracking study showed that the highest conversion and product fraction of bio-gasoline and bio-aviation fuel were exhibited by molybdenum nitride-bentonite 8 mEq g⁻¹. The catalyst was later used to optimize the hydrocracking process using RSM-CCD. The effects of the process variables such as temperature, contact time, and catalyst to feed ratio, on the response variables, such as conversion, oil, gas, and coke yield, were investigated. The analysis of variance showed that the proposed quadratic model was statistically significant with adequate precision to estimate the responses. The optimum conditions in the hydrocracking process were achieved at a temperature of 731.94 K, contact time of 0.12 h, and a catalyst to feed ratio of 0.12 w/v with a conversion of 78.33%, an oil yield of 50.32%, gas yield of 44.00% and coke yield of 5.73%. The RSM-CCD was demonstrated as a suitable method for estimating the hydrocracking process of palm oil using a MoN-bentonite catalyst due to its closeness to the optimal value of the expected yield. This study provided a potential catalyst of based on bentonite modified using molybdenum nitride for the hydrocracking of palm oil.

In this study, molybdenum nitride-bentonite was successfully employed for the reaction of hydrocracking of palm oil to produce a bio-gasoline and bio-aviation fuel.

Synthesis of Nickel-loaded Sulfated Zirconia Catalyst and Its Application for Converting Used Palm Cooking Oil to Gasoline via Hydrocracking Process

The synthesis of the nickel-loaded sulfated zirconia catalyst (Ni-SZ) and its application for the hydrocracking process have been carried out. This work has been conducted to determine the activity and selectivity from various Ni concentrations loaded on sulfated zirconia (SZ) in the hydrocracking of used palm cooking oil. The synthesis technique was preceded by sulfation of ZrO2 through incipient wetness impregnation method using H2SO4 solution and then continued with the impregnation of Ni via hydrothermal method employing NiSO4 · 6H2O precursor salt. The hydrocracking process was performed in a fix-bed microreactor at the optimum temperature (350 °C). The SZ loaded with 3 wt% of Ni (Ni-SZ 3) successfully produced the highest liquid product (44.25 wt%) and selectivity on gasoline (100 %). Besides, the gasoline fraction in the liquid product was dominated by unwanted aromatics compounds. The excellent performance of Ni-SZ 3 due to it has high acidity value, specific surface area, and Ni content.

Kinetic Model of Crude Palm Oil Hydrocracking Over Ni/Mo ZrO2–Pillared Bentonite Catalyst

Crude Palm Oil hydrocrcaking has been carried out over Ni/Mo ZrO2–pillared bentonite catalyst in a fixed bed reactor. Crude Palm Oil hydrocracking over Ni/Mo ZrO2–pillared bentonite catalyst formed 3 products i.e. gas, oil and coke. The oil product from Crude Palm Oil hydrocracking was analyzed by using gas chromatography to determine its composition. Three types of fraction were classified i.e. gasoline, kerosene and diesel oil. In this research, the focused of the study is of hydrocracking kinetics by using lump kinetic models. The kinetic model was solved by using the software MATLAB R2018b involves the effect of catalyst activity on the reaction rate. The results of the kinetic study show that the 4-lump (Crude Palm Oil, gas coke and oil) and 6-lump reaction models (Crude Palm Oil, gas, coke, gasoline, kerosene and diesel) can be used to explain the Crude Palm Oil hydrocracking over Ni/Mo ZrO2–pillared bentonite catalyst. The 4-lump kinetic model has 5 rate constants and the 6-lump kinetic model has 14 rate constants.

Hydrothermal preparation of a platinum-loaded sulphated nanozirconia catalyst for the effective conversion of waste low density polyethylene into gasoline-range hydrocarbons

A platinum-loaded sulphated nanozirconia (Pt/nano ZrO₂–SO₄) bifunctional metal–acid catalyst was synthesized using a hydrothermal process. The nano ZrO₂–SO₄ was initially prepared by dispersing the nano ZrO₂ in H₂SO₄, followed by wet impregnation via heating in an aqueous PtCl₄ solution. This material was subsequently calcined and reduced under hydrogen gas to produce the catalyst. The Pt/nano ZrO₂–SO₄ was found to be a highly active, selective and stable solid acid catalyst for the conversion of waste low density polyethylene (LDPE) to high value hydrocarbons. The catalytic activity and stability of this material were evaluated during the hydrocracking of waste LDPE while optimizing the reaction temperature, time and catalyst-to-feed ratio. The activity of catalyst prepared by hydrothermal was attributed to highly dispersion of Pt species interacting with the support and inhibition of the agglomeration process. The impregnation method of hydrothermal generated highly active and selective catalyst with Pt loads of 1 wt%. The hydrocracking of waste LDPE over Pt/nanoZrO₂–SO₄ at 250 °C for 60 min with a catalyst-to-feed proportion of 1 wt% gave the largest gasoline fraction.

A Pt/nano ZrO₂–SO₄ bifunctional metal–acid catalyst was synthesized using a hydrothermal process.

The Jahn-Teller effect in mixed aqueous solution: the solvation of Cu2+ in 18.6% aqueous ammonia obtained from ab initio quantum mechanical charge field molecular dynamics

The solvation structure and dynamics of Cu2+ in 18.6 % aqueous ammonia have been investigated using an ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulation approach at the Hartree–Fock (HF) level of theory applying the LANL2DZ ECP and Dunning DZP basis sets for Cu2+, ammonia and water, respectively. During a simulation time of 20 ps, only NH3 molecules are observed within the first solvation shell of Cu2+, resulting in the formation of an octahedral [Cu(NH3)6]2+ complex. While no exchange of these ligands with the second solvation shell are observed along the simulation, the monitoring of the associated N-Ntrans distances highlight the dynamics of the associated Jahn-Teller distortions, showing on average 2 elongated axial (2.19 Å) and 4 equatorial Cu–N bonds (2.39 Å). The observed structural properties are found in excellent agreement with experimental studies. In addition, an NBO analysis was carried out, confirming the strong electrostatic character of the Cu2+–NH3 interaction.

The Catalytic Performance of ZrO2-SO4 and Ni/ZrO2-SO4 Prepared from Commercial ZrO2 in Hydrocracking of LDPE Plastic Waste into Liquid Fuels

Catalytic activity and selectivity toward liquid fuels production of ZrO2, SZ, 0.5NiSZ, 1.0NiSZ, and 1.5NiSZ catalysts with different physicochemical properties, in hydrocracking process upon the second stage of sequential LDPE plastic conversion method after pyrolysis process, were examined. The hydrocracking reaction was carried out at 300°C under 20 mL/min of hydrogen gas flow for 1 h. Modifying commercial ZrO2 with sulfate and Ni enhances the acidity of catalyst, even though there is a decrease in surface area. The increase in acidity of catalyst results in the higher liquid fuels conversion. The presence of nickel reduces olefins content and aromatic content of liquid product, and also reduces coke formation. The highest liquid yield (44.32%) that composed by 66.25% fraction of gasoline is produced over 1.5NiSZ which has the highest catalyst acidity.

Penggunaan Metode Semiempirik AM1 Untuk Pemilihan Monomer Fungsional Efektif Pada Prasintesis Polimer Tercetak Diazinon

Pemilihan monomer fungsional yang efektif untuk sintesis Molecular Imprinted Polymer (MIP)untuk diazinon dapat dilakukan dengan pendekatan kimia komputasi dengan menerapkan metode semiempirik AM1. Proses seleksi menggunakan parametermomen dipol, energi interaksi, dan ikatan hidrogen yang terbentuk. Energi interaksi yang optimum menunjukkan kompleks yang terbentuk stabildan mengindikasikan MIP akan dapat terbentuk baik.Semua perhitungan pada penelitian ini dilakukan dengan menggunakan software Hyperchem 7.5. Hasil penelitian menunjukkan monomer fungsional efektif untuk prasintesis polimer tercetak diazinon yaitu akrilamida, asam akrilat, asam metakrilat, hidroksi etil metakrilat, asam urokanat, asam itakonat, dan asam urokanat etil ester. Hasil ini secara teoritik  dapat memberikan informasi mengenai monomer fungsional efektif yang dapat digunakan sebagai pertimbangan sintesis MIP untuk diazinon dengan selektivitas relatif baik.

Polysulfonylamine, CXVIII Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Drei prim. -Ammonium-dimesylamide mit zwei- oder dreidimensionalen Wasserstoffbrückenmustern/Polysulfonylamines, CXVIII Hydrogen Bonding in Crystalline Onium Dimesylamides: Three prim. -Ammonium Dimesylamides Exhibiting Two- or Three-Dimensional Hydrogen Bond Patterns

In order to study hydrogen bonding patterns in primary ammonium salts and the hydrogen bond acceptor potential of the dimesylamide anion, low-temperature X-ray structures have been determined for the 1:1 salts RNH3 +(MeSO2)2N- , where R = Et (1, monoclinic, space group P21/n, two independent formula units A and B) or 1-adamantyl (2, monoclinic, P21/C) and for the 1:2 salt [H3NCH2CH2NH3]2+ ·2 (MeSO2)2N- (3, monoclinic, P21/n, cation crystallographically centrosymmetric). The NH3 + donor groups form two-centre or three-centre hydrogen bonds to four (B) or three (A, 2, 3) adjacent anions, giving rise to fundamentally different networks. The crystal packing of 1 displays a three-dimensional system of eight independent H bonds and may be viewed as a commensurate ionic self-clathrate, in which finite (A)2 cyclodimers are inserted as guest entities into parallel tunnels between infinite (B)∞ tapes. In contrast, owing to the steric demands of the 1-adamantyl group, compound 2 merely exhibits a twodimensional pattern constructed from four independent H bonds and leading to cation-anion sheets. In the packing of 3, two crystallographically independent H bonds generate a tape substructure of cations and anions in the ratio 1:2; these tapes are cross-linked into a three-dimensional network via a third independent H bond. In each of the structures, short C -H ··· A contacts (A = N- and/or O) with H ··· A ≤ 260 pm and C - H ··· A ≥ 130° are observed.

Polysulfonylamine, CLXI. Ein neuartiges 1,2-Dihydroimidazochinolinylium-Kation: Zufällige Isolierung und Kristallstruktur des entsprechenden Dimesylamids Polysulfonylamines, CLXI. A Novel 1,2-Dihydroimidazoquinolinylium Cation: Serendipitous Isolation and Crystal Structure of the Corresponding Dimesylamide

Orange-coloured 1,2-dihydro-2,2-dimethyl-imidazo[4,5,1-ij]quinolinylium dimesylamide (1) was accidentally obtained on treating 8-aminoquinoline with one equivalent of dimesylamine in acetone solution. To the best of the authors’ knowledge, the tricyclic cation in question or congeners thereof have not been reported previously. The crystal structure of 1 (monoclinic, space group P21/c, Z = 4; - 130 °C) consists of (MeSO2)N- layers, between which the cations are intercalated to form centrosymmetric (π-π)-bonded pairs. Each cation is connected to the adjacent anion layers by a conventional NDH···(O,N) three-centre hydrogen bond and a set of weak C(sp2)DH···O = S and CH2DH···O = S interactions.

Polysulfonylamine, CLIII [1]. Schwache Wasserstoffbrücken mit aktivierten Methyldonoren: Kristallstrukturen von Cholinium-, Betainium- und Dimethyl[2-(dimethylamino)ethyl]ammonium-dimesylamid Polysulfonylamines, CLIII [1]. Weak Hydrogen Bonding with Activated Methyl Donors: Crystal Structures of Cholinium, Betainium and Dimethyl[2-(dimethylamino)ethyl]ammonium-dimesylamide

In order to study weak hydrogen bonds originating from inductively activated C(sp3)-H donor groups, low-temperature X-ray structures are reported for three onium salts of general formula BH+(MeSO2)2N-, where BH+ is Me3N+CH2CH2OH (1; orthorhombic, space group P212121, Z′ = 1), Me3N+CH2C(O)OH (2; orthorhombic, P212121, Z′ = 1), or Me2HN+CH2CH2NMe2 (3; monoclinic, P21/c, Z′ = 1). The asymmetric units consist of cationanion pairs assembled by an O-H···O=S hydrogen bond in 1, an O-H···N- bond in 2, and an N+-H ··· N- bond in 3. The packings display a plethora of short interionic C(sp3)-H···O/N contacts that are geometrically consistent with weak hydrogen bonding; those taken into consideration have normalized parameters d(H ··· O) ≤ 269 pm, d(H···N) ≤ 257 pm and θ(C-H···O/N) ≥ 127°. The roles of the weak hydrogen bonds are as follows: In structures 1 and 3, the anions are associated into corrugated layers, which intercalate catemers of cations (1) or stacks of discrete cations (3), whereas structure 2 involves cation catemers surrounded by four anion catemers and vice versa; moreover, all cations are linked to adjacent anions by several weak hydrogen bonds (and to one anion in particular by the strong H bond). Among the cation-anion interactions, the N+(CH2-H···)3O tripod pattern arising in 1 and 2 is of special interest.

Polysulfonylamine, CXLII [1]. Ein supramolekulares Monomer-Dimer-Paar: Starke und schwache Wasserstoffbrücken in den Kristallstrukturen von Pyridinium-dimesylamid und 4,4´-Bipyridindiium-bis(dimesylamid) / Polysulfonylamines, CXLII [1]. A Supramolecular Monomer-Dimer Pair: Strong and Weak Hydrogen Bonding in the Crystal Structures of Pyridinium Dimesylamide and 4,4´-Bipyridinediium Bis(dimesylamide)

In order to study packing arrangements and hydrogen bonding networks, low-temperature X-ray structures were determined for pyH+(MeSO2)2N- (M, orthorhombic, space group P212121, Z′ = 1) and 4,4′-bipyH2 2+ ·(MeSO2)2N- (D, monoclinic, C2/c, Z′ = 0.5). The structures consist of ionic formula entities assembled by N+-H···N- hydrogen bonds; the dication in D displays crystallographic C2 symmetry and has its two pyridyl moieties twisted by 43.9°. According to the packing architectures, D represents a supramolecular dimer of the monomeric congener M. In particular, the (MeSO2)2N- ions of the M structure are associated via short C(sp3) - H···O contacts to form a diamondoid network, whereas in D a topologically congruent framework is constructed from weakly hydrogen-bonded [(MeSO2)N-]2 nodes. Hexagonal channels in the anion substructures each include two adjacent stacks of monomeric pyH+ or “dimeric” 4,4-bipyH2 2+ cations that are linked to the channel walls by the strong hydrogen bond(s) and a set of short Car-H···O contacts. All C - H···O taken into consideration have normalized parameters d(H···O) ≤ 270 pm and θ(C - H···O) ≥ 115°.

Polysulfonylamine, CXXVII [1] Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Ein robustes Achtring-Synthon als Bestandteil dreidimensionaler Wasserstoffbrückenmuster / Polysulfonylamines, CXXVII [1] Hydrogen Bonding in Crystalline Onium Dimesylamides: A Robust Eight-Membered Ring Synthon as a Component in Three-Dimensional Hydrogen Bonding Patterns

In order to study crystal packings and hydrogen bonding frameworks, low-temperature X-ray structures were determined for three onium salts of general formula B H+(MeSO2)2N−, where BH+ is acetamidinium (1, monoclinic, space group P21/c, Z = 4), guanidinium (2, monoclinic, P21/c, Z = 4), or 4,6-diamino-2-thioxo-2,3-dihydropyrimidinium (3, monoclinic P21/n, Z = 4). In every case the ions create three-dimensional N − H ∙∙∙ N/O networks, in which all N − H donors of the cations and four (in 1) or five (2, 3) acceptors of the anion are involved; non-conventional secondary bonds, e.g. C − H ∙∙∙ O/N, do not play an important role in the packings. For the isotypic structures 1 and 2, congruencies and dissimilarities of the hydrogen bonding patterns are discussed in detail. Despite the structural and chemical differences between the cations and the way in which they are attached to the anion, each of the three structures displays a robust eight-membered ring synthon [N2 = R2 2(8), antidromic] constructed via two-centre hydrogen bonds from a syn, syn-sequence H − N − C (sp2) −N −H of the respective cation and a V-shaped O − S (sp3) − N fragment of the anion. Although the networks in 2 and 3 contain several N − H (∙∙∙ O)2 three-centre interactions, the two-point connectivity of the synthon is distinctly preserved. The results indicate that the (MeSO2)2N− ion may be utilized in crystal engineering as a dependable building block.

Polysulfonylamine, CXVII Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Sechs systematisch variierte sek.-Ammonium-dimesylamide mit sechs verschiedenen null-, ein-oder zweidimensionalen Wasserstoffbrückenmustern/ Polysulfonylamines, CXVII Hydrogen Bonding in Crystalline Onium Dimesylamides: Six Systematically Varied sec. - Ammonium Dimesylamides Exhibiting Six Different Zero-, One-, or Two-Dimensional Hydrogen Bonding Patterns

In order to examine packing preferences and hydrogen bond patterns in secondary ammonium salts, low-temperature X-ray analyses were conducted for six compounds of general formula R2NH2 +MeSO2)2 N-, where R2NH2 + = Me2NH2 + (1, triclinic, space group P1̄̄), MeEtNH2 +,(2, monoclinic, P21/c), Et2NH2 + (3. triclinic, P1), pyrrolidinium (4, triclinic, P1), piperidinium (5, monoclinic, C2/c) or morpholinium (6, monoclinic, P21/c). Throughout the series, the constant anion retains a rigid conformation approximating to C2 symmetry and thus provides a geometrically reliable set of five potential hydrogen bond acceptors. Nevertheless, the six compounds exhibit a variety of unpredictable packing patterns, showing that, in unfavourable cases, the steric demands of molecular fragments not involved in hydrogen bonding can substantially alter the structure of a family of ionic crystals. In the present structures, the NH2 + donor groups form hydrogen bonds N+-H···N-/O to two (3-6) or three (1,2) adjacent anions. The occurrence of various two-, three- and four-centre hydrogen bonds leads to six different patterns, resulting in cation-anion layers (1, 2), discrete formula unit dimers (3, 4) or cation-anion chains (5, 6); in the morpholinium salt 6, these chains are associated into layers by a weak N+ - H ··· O(cation) interaction. In each of the crystal packings, short C-H···O contacts with H···O ≤ 270 pm and C-H ···O ≥ 130° are observed.

Polysulfonylamine, XCVI [1]. Homokonjugate aus Di(organosulfonyl)aminen und ihren konjugierten Anionen: Vier Kristallstrukturen mit asymmetrischen [N -H ··· N ]--Wasserstoffbrücken / Polysulfonylamines, XCVI [1]. Homoconjugates Formed from Di(organosulfonyl)amines and their Conjugate Anions: Four Crystal Structures Featuring A symmetric [ N - H ··· N ]- Hydrogen Bonds

The following compounds were prepared by cocrystallization of their components from MeOH or MeCN and structurally characterized by low-temperature X-ray diffraction: Na[N(SO2Me)2]·HN(SO2Me)2·2 (12-crown-4) (2, orthorhombic, space group Pna21). Na[N(SO2Me)·HN(SO2Me)·(15-crown-5) (3, monoclinic. P21/n), Na[N(SO2Ph)2] · HN(SO2Ph)2 · 2 (12-crown-4) (4. monoclinic. P21). (MeNH)2COHN(SO2Ph)2·0.5 MeCN (5, monoclinic. P21/n). The four structures exhibit [(RSO2)2N-H ··· N(SO2R)2]- anions as rare examples of intermolecular [N-H ···N]- homo- conjugates. The N ··· N distances of the asymmetric hydrogen bonds are. in order. 266.9(6). 276.0(3). 291.3(4) and 279.4(2) pm. the corresponding N-H···N angles amounting to 137(10), 176(3), 177(4) and 177(2)°. The asymmetry of the hydrogen bonds is clearly reflected in the geometry of the NS2 groups (amine moieties: N-S 162.3-165.2 pm. S-N-S 124.5-127.1°; amide moieties: N-S 159.7-161.8 pm. S-N-S 119.1-122.6°). The dihedral angles formed by the NS2 planes vary from 51.8° in 4 to 87.6° in 5. The crystal lattices of 2 and 4 consist of discrete ions, sandwich-type [Na(12-crown-4)2]+ complexes acting as the counter-ions. In 3. Na+ is coordinated in an out-of-cavity pattern by the five polyether oxygen atoms and further accepts two Na-O bonds from the amide moiety of the complex anion [Na-O(crown) 241.5(2)-249.9(2), Na-O(anion) 235.0(2) and 263.9(2) pm]. Thе surprising structure of 5 contains homoconjugated 1.3-dimethylurea cations [(MeNH)2C-O-H ··· O=C(NHMe)2]+, which are formed via a very strong asymmetric [O-H ···O]+ hydrogen bond [О···О 247.7(2) pm. O-H ··· O 172(3)°] and are associated with the amide moieties of the anions through a set of N-H···О bonds to form infinite chains: the MeCN molecules occupy lattice cavities.

Polysulfonylamine, CXLIII [1], Rolle schwacher Wasserstoffbrücken (C - H···O) in den Kristallstrukturen von 2,6-Dimethylpyridinium-, 1-Hydroxypyridinium- und Imidazolium-dimesylamid / Polysulfonylamines, CXLIII [1], Role of Weak Hydrogen Bonds (C - H···O) in the Crystal Structures of 2,6-Dimethylpyridinium , 1-Hydroxypyridinium and Imidazolium Dimesylamide

In order to study hydrogen bonding networks in ionic crystals, low-temperature X-ray structures were determined for three onium salts of general formula BH+(MeSO2)2N- , where BH+ is 2,6-dimethylpyridinium (1; monoclinic, space group P21/c, Z′ = 1), 1-hydroxypyridinium (2; triclinic, P1̅, Z′ = 1), or imidazolium (3; monoclinic, Cc, Z′ = 1). The asymmetric units consist of cation-anion pairs assembled in 1 and 3 by ordinary N+ - H···N hydrogen bonds, in 2 by a very short N+ - O - H···N- bond belonging to the class (+/-)CAHB [H···O 148(3), O···N 253.5(2) pm, O - H···N 175(3)°]. The second N -H donor of the imidazolium ion is involved in a nearly symmetric N - H (···O)2 three-centre bond to two different anions. In the pyridine derivatives, the (MeSO2 )2N- ions are associated via short C(sp3) - H···O contacts to form a three-dimensional framework of corrugated and cross-linked layers (1) or an assembly of discrete corrugated layers (2). As a common feature, these anion substructures are pervaded by hexagonal channels parallel to x, each one accommodating two stacks of cations that are linked to the channel walls by the unique strong hydrogen bond and a set of short Car - H···O contacts; moreover, cations drawn from adjacent stacks in structure 2 create inversion-symmetric dimers based upon a short Car - H···O(H) - N interaction. In contrast, the structure of 3 displays planar anion layers assembled by short C(sp3 ) - H···O contacts, intercalating the cations with their ring planes perpendicular to the layer planes and binding them by means of the strong hydrogen bonds and three Car -H···O interactions. All C - H···O taken into consideration have normalized parameters d( H···O) ≤ 267 pm and θ(C - H···O) ≥ 121°.

Benzo-18-krone-6 -Acetonitril (1/2): Kristallisation und Tieftemperatur- Röntgenstrukturanalyse / Benzo-18 -crown-6 -Acetonitrile (1/2): Crystallization and Low-Temperature X-Ray Analysis

Benzo-18 -crown-6 -Acetonitrile (1/2), Crystal Structure Single crystals of the title complex resulted fortuitously during an attempt to co-crystallise MeN(SO2Me)2 with benzo-18-crown-6 from an MeCN solution at -30 °C. The crystal structure has been determined via data collection at -100 °C (monoclinic, space group P21/n, Z = 4). The nitrile molecules are located with their me­ thyl groups above and below the plane of the 18-membered crown ring, the Me hydrogen atoms being rotationally disordered about the MeCN axes; C(methyl)···O(crown) distances range from 309.4(3) to 384.9(3) pm.

Polysulfonylamine, CXXVI [1] Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Ein robustes Achtring-Synthon in Koexistenz mit einem dritten Wasserstoffbrückenmotiv - Cyclodimere, Ketten, supramolekulare Bindungsisomere und ein fünffach verwobenes dreidimensionales (C-H ∙∙∙ O - Netzwerk / Polysulfonylamines, CXXVI [1] Hydrogen Bonding in Crystalline Onium Dimesylamides: A Robust Eight- Membered Ring Synthon in Coexistence with a Third Hydrogen Bonding Motif - Cyclodimers, Chains, Supramolecular Linkage Isomers, and a Quintuply Interwoven Three-Dimensional C - H ∙∙∙ O Network

As an exercise in crystal engineering, low-temperature X-ray structures were determined for six rationally designed ionic solids of general formula BH+(MeSO2)2N−, where BH+ is 2-aminopyridinium (2, monoclinic, space group P21/c, Z = 4), 2-aminopyrimidinium (3, orthorhombic, Pbca, Z = 8), 2-aminothiazolium (4, orthorhombic, Pbcn, Z = 8), 2-amino-6-methylpyridinium (5, solvated with 0.5 H20, monoclinic, C2/c, Z = 8), 2-amino-1,3,4-thiadiazolium (6, triclinic, P1̄, Z = 2), or 2-amino-4,6-dimethylpyrimidinium (7, orthorhombic. Fdd2, Z = 16). The onium cations in question exhibit a trifunctional hydrogen-bond donor sequence H − N (H*)-C (sp2) − N − H , which is complementary to an O − S (sp3)−N fragment of the anion and simultaneously expected to form a third hydrogen bond via the exocyclic N − H* donor. Consequently, all the crystal packings contain cation-anion pairs assembled by an N − H ∙∙∙ N and an N −H ∙∙∙ O hydrogen bond, these substructures being mutually associated through an N − H* ∙∙∙ O bond. For the robust eight-membered ring synthon within the ion pairs [graph set N2 = R2 2(8), antidromic], two supramolecular isomers were observed: In 2 and 3, N − H ∙∙∙ N originates from the ring NH donor and N − H ∙∙∙ O from the exocyclic amino group, whereas in 4-7 these connectivities are reversed. The third hydrogen bond, N − H*∙∙∙ O , leads either to chains of ion pairs (generated by a 21 transformation in 2-4 or by a glide plane in 5) or to cyclic dimers of ion pairs (Ci symmetric in 6, C2-symmetric in 7). The overall variety of motifs observed in a small number of structures reflects the limits imposed on the prediction of hydrogen bonding patterns. Owing to the excess of potential acceptors over traditional hydrogen-bond donors, several of the structures display prominent non-classical secondary bonding. Thus, the cyclodimeric units of 6 are associated into strands through short antiparallel O ∙∙∙ S(cation) interactions. In the hemihydrate 5, two independent C-H(cation) ∙∙∙ O bonds generate a second antidromic R2 2(8) pattern, leading to sheets composed of N − H ∙∙∙ N/O connected catemers; the water molecules are alternately sandwiched between and O - H ∙∙∙ O bonded to the sheets to form bilayers, which are cross-linked by a third C − H (cation ) ∙∙∙ O contact. The roof-shaped cyclodimers occurring in 7 occupy the polar C2 axes parallel to z and build up hollow Car− H ∙∙∙ O bonded tetrahedral lattices; in order to fill their large empty cavities, five translationally equivalent lattices mutually interpenetrate.

PEMANFAATAN KATALIS NI/ZEOLIT PADA HIDROGENASI KATALITIK ETIL PALMITAT MENJADI SETIL ALKOHOL

The catalytic hydrogenation of methyl palmitate to cetyl alcohol using Ni supported on activated natural zeolite catalysts (Ni/Zeolite) has been carried out. In this work, the effect of catalyst amounts and H2 flow rate on methyl palmitate conversion and yield of cetyl alcohol were studied. Catalytic hydrogenation was performed in stainless steel fixed bed reactor. The methyl palmitate (10 g) was loaded into the reactor vessel at 400 °C for 30 minutes. In order to study the effects of catalyst amount at constant H2 flow rate, the catalyst were varied i.e. 5, 10, and 15 g. To investigate the effects of H2 flow rate were varied from 20, 40, and 60 mL.min-1 at constant catalyst amount. The composition of the products was analyzed by GC and GC-MS. The results showed that methyl palmitate conversion increase with the increasing of catalyst amount. The highest methyl palmitate conversion (45.62 %) and yield of cetyl alcohol (36.44 %) were obtained for 15 g catalyst and 40 mL. min-1 H2 flow rate.

Base-specific and enantioselective studies for the DNA binding of iron(II) mixed-ligand complexes containing 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine

Base specificity and enantioselectivity for the DNA binding of [Fe(phen)2(dppz)]2+ (phen=1,10-phenanthroline and dppz=dipyrido[3,2-a:2',3'-c]phenazine) have been studied by determining the equilibrium binding constant (Kb) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)2], poly[(dG-dC)2] and poly[(dI-dC)2] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)2(dppz)]2+ prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)2] and poly[(dI-dC)2] rather than into the G-C sequences of poly[(dG-dC)2] or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppz)]2+ is base-dependent in nature. The Delta-enantiomer of [Fe(phen)2(dppz)]2+ is preferentially intercalated into the base pairs of poly[(dG-dC)2] or ct-DNA as indicated by its CD spectral profiles. On the other hand, the Lambda-enantiomer of [Fe(phen)2(dppz)]2+ is favorably intercalated into poly[(dA-dT)2] or poly[(dI-dC)2] as suggested by the opposite CD spectral profile. This preferential binding of Lambda-[Fe(phen)2(dppz)]2+)for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non-intercalated) phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (Kinv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron (II) complex.

Salt-dependent binding of iron(II) mixed-ligand complexes containing 1,10-phenanthroline and dipyrido[3,2-a:2′,3′-c]phenazine to calf thymus DNA

The salt-dependent binding of racemic iron(II) mixed-ligand complex containing 1,10-phenanthroline (phen) and dipyrido[3,2-a:2',3'-c]phenazine (dppz), [Fe(phen)2(dppz)]2+ to calf thymus DNA (ct-DNA) has been characterized by UV-VIS spectrophotometric titration. The equilibrium binding constant (Kb) of the iron(II) complex to ct-DNA decreases with the salt concentration in the solution. The slope, SK=(deltalog Kb/deltalog [Na2+]) has been found to be 0.49, suggesting that, in addition to intercalation, considerable electrostatic interaction is also involved in the ct-DNA binding of [Fe(phen)2(dppz)]2+. The calculation of non-electrostatic binding constant (Kt(o)) based on polyelectrolyte theory has revealed that the non-electrostatic contribution to the total binding constant (Kb) increases significantly with the increase in [Na+] and reaches 36% at 0.1 M NaCl. On the other hand, the contribution of the non-electrostatic binding free energy (DeltaGt(o)) to the total binding free energy change (DeltaGo) is considerably large, i.e. 87% at [Na+]=0.1 M, suggesting that the stabilization of the DNA binding is mostly due to the contribution of non-electrostatic process. Moreover, the effect of specific ligand substitutions on DeltaGo has been rigorously evaluated using the quantity DeltaDeltaGt(o), i.e. the difference in DeltaGt(o) relative to that of the parent iron(II) complex, [Fe(phen)3]2+, indicating that each substitution of phen by dip and dppz contributes 7.5 and 17.5 kJ mol(-1), respectively to more favorable ct-DNA binding.

DNA-Binding Properties of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a:2’,3’-c]phenazine

An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2’,3’- c]phenazine (dppz), [Fe(phen)2(dppz)]2+, has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen)2(dppz)]2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (Δ Tm = 21 °C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen)2(dppz)]2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative TΔ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen)2(dppz)]2+. This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ -enantiomer indicates that Δ -[Fe(phen)2(dppz)]2+ is preferentially bound to ct-DNA

DNA binding of iron(II) complexes with 1,10-phenanthroline and 4,7-diphenyl-1,10-phenanthroline: salt effect, ligand substituent effect, base pair specificity and binding strength

The DNA binding of iron(II) mixed-ligand complexes containing 1,10-phenanthroline(phen) and 4,7-diphenyl-1,10-phenanthroline(dip), [Fe(phen)(3)](2+), [Fe(phen)(2)(dip)](2+) and [Fe(phen)(dip)(2)](2+) has been characterized by spectrophotometric titration and melting temperature measurements. The salt concentration dependence of the binding constant has allowed us to dissect the DNA-binding constant and free energy change of each iron(II) complex into the nonelectrostatic and polyelectrolyte contributions. A comparison of the nonelectrostatic components in the binding free energy changes among iron(II) complexes has made it possible to rigorously evaluate the contribution of the ligand substituents to the DNA-binding event. The peripheral substitution of phen by two phenyl groups increases the nonelectrostatic binding constant of the iron(II) complex more than 20 times, which is equivalent to approximately 7.5 kJ mol(-1) of more favorable contribution to the DNA binding. In general, the iron(II) complexes studied have higher affinity towards the more facile A-T sequence than the G-C sequence. This preferential binding may be attributed to the steric effect induced by the ancillary part of the ligands in the course of DNA binding. The binding of disubstituted iron(II) complex to DNA is quite strong as reflected in the modest increase in the denaturation temperature (T(m)) of double helical DNA upon the interaction with the iron(II) complex.

Polysulfonylamine, CLI [1]. Starke und schwache Wasserstoffbrücken in den Kristallstrukturen von 8-Hydroxychinolinium- und 8-Aminochinolinium-dimesylamid / Polysulfonylamines, CLI [1]. Strong and Weak Hydrogen Bonding in the Crystal Structures of 8-Hydroxyquinolinium and 8-Aminoquinolinium Dimesylamide

In order to study hydrogen bonding networks and packing arrangements in ionic organic crystals, low-temperature X-ray structures were determined for two chemically related onium salts BH+(MeSO2)2ND, where BH+ is 8-hydroxyquinolinium (1; monoclinic, space group P21/ c, Z´ = 1) or 8-aminoquinolinium (2; monoclinic, P21/n, Z´ = 1). The packings are governed by strong hydrogen bonds, π-π stacking interactions and weak hydrogen bonding. In both compounds, hydrogen bonds using the NH/OH donors of the cations and O/N acceptors of the anion result in simple chain polymeric structures, which extend parallel to the y axis and are propagated by translation (1) or 21 transformation (2). Moreover, an intramolecular N- H···O hydrogen bond is present in the 8-hydroxyquinolinium cation. As a common feature, the anion substructures are pervaded by hexagonal channels parallel to y, each one accommodating either two separate stacks of translation related cations (1) or a unique (merged) stack of inversion related cations (2). The crystal cohesion is reinforced by numerous weak hydrogen bonds of the types Car-H···O=S and CH2-H···O=S, the latter creating in each structure a topologically different double-chain ribbon of anions. All C-H···O contacts taken into consideration have normalized parameters d(H···O) ≤ 268 pm and θ(CDH···O) ≥ 126°.