628 research outputs found
The role of alkane coordination in CâH bond cleavage at a Pt(II) center
The rates of CFormula H bond activation for various alkanes by [(NâN)Pt(Me)(TFEd3)]+ (N Formula N = ArFormula NFormula C(Me)Formula C(Me)Formula NFormula Ar; Ar = 3,5-di-tert-butylphenyl; TFE-d3 = CF3CD2OD) were studied. Both linear and cyclic alkanes give the corresponding alkene-hydride cation [(NâN)Pt(H)(alkene)]+ via (i) rate determining alkane coordination to form a CFormula H {sigma} complex, (ii) oxidative cleavage of the coordinated CFormula H bond to give a platinum(IV) alkyl-methyl-hydride intermediate, (iii) reductive coupling to generate a methane {sigma} complex, (iv) dissociation of methane, and (v) beta-H elimination to form the observed product. Second-order rate constants for cycloalkane activation (CnH2n), are proportional to the size of the ring (k ~ n). For cyclohexane, the deuterium kinetic isotope effect (kH/kD) of 1.28 (5) is consistent with the proposed rate determining alkane coordination to form a CFormula H {sigma} complex. Statistical scrambling of the five hydrogens of the Pt-methyl and the coordinated methylene unit, via rapid, reversible steps ii and iii, and interchange of geminal CFormula H bonds of the methane and cyclohexane CFormula H {sigma} adducts, is observed before loss of methane
Product Protection, the Key to Developing High Performance Methane Selective Oxidation Catalysts
Selective, direct conversion of methane to methanol might seem an impossible task since the CâH bond energy of methane is 105 kcal mol^(â1) compared to the CâH bond energy for methanol of 94. We show here that the Catalytica catalyst is successful because the methanol is protected as methyl bisulfate, which is substantially less reactive than methanol toward the catalyst. This analysis suggests a limiting performance for systems that operate by this type of protection that is well above the Catalytica system
Transition state energy decomposition study of acetate-assisted and internal electrophilic substitution CâH bond activation by (acac-O,O)_2Ir(X) complexes (X = CH_3COO, OH)
Chelate-assisted and internal electrophilic substitution type transition states were studied using a DFT-based energy decomposition method. Interaction energies for benzene and methane CâH bond activation by (acac-O,O)_2Ir(X) complexes (X = CH_3COO and OH) were evaluated using the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA). A ratio of ~1.5:1 for forward to reverse charge-transfer between (acac-O,O)_2Ir(X) and benzene or methane transition state fragments confirms âambiphilicâ bonding, the result of an interplay between the electrophilic iridium center and the internal base component. This analysis also revealed that polarization effects account for a significant amount of transition state stabilization. The energy penalty to deform reactants into their transition state geometry, distortion energy, was also used to understand the large activation energy difference between six-membered and four-membered acetate-assisted transition states and help explain why these complexes do not activate the methane CâH bond
Iridium complexes bearing a PNP ligand, favoring facile C(sp^3)âH bond cleavage
Hydrogen iodide is lost upon reaction of PNP with IrI_3, where PNP = 2,6-bis-(di-t-butylphosphinomethyl)pyridine to give crystallographically characterized Ir(PNP)*(I)_2, which reacts with H_2 to give Ir(PNP)(H)(I)_2. Ir(PNP)(Cl)_3 is relatively inert towards the intramolecular CâH activation of the tert-butyl's of the PNP ligand
Ligand Lone-Pair Influence on Hydrocarbon C-H Activation: A Computational Perspective
Mid to late transition metal complexes that break hydrocarbon C-H bonds by transferring the hydrogen to a heteroatom ligand while forming a metal-alkyl bond offer a promising strategy for C-H activation. Here we report a density functional (B3LYP, M06, and X3LYP) analysis of
cis-(acac)_2MX and TpM(L)X (M=Ir, Ru, Os, and Rh; acac=acetylacetonate, Tp=tris(pyrazolyl)-borate; X=CH_3, OH, OMe, NH_2, and NMe_2) systems for methane C-H bond activation reaction kinetics and thermodynamics.We address the importance of whether a ligand lone pair provides an
intrinsic kinetic advantage through possible electronic d_Ï-p_Ï repulsions for M-OR and M-NR_2 systems versus M-CH_3 systems. This involves understanding the energetic impact of the X ligand group on ligand loss, C-H bond coordination, and C-H bond cleavage steps as well as understanding how the nucleophilicity of the ligand X group, the electrophilicity of the transition metal center, and cis-ligand stabilization effect influence each of these steps.We also explore how spectator ligands and second- versus third-row transition metal centers impact the energetics of each of these C-H activation steps
Acceleration of Nucleophilic CH Activation by Strongly Basic Solvents
(IPI)Ru(II)(OH)_n(H_2O)_m, 2, where IPI is the NNN-pincer
ligand, 2,6-diimidizoylpyridine, is shown to catalyze H/D exchange
between hydrocarbons and strongly basic solvents at higher rates
than in the case of the solvent alone. Significantly, catalysis by 2
is accelerated rather than inhibited by increasing solvent basicity.
The evidence is consistent with the reaction proceeding by base
modulated nucleophilic CH activation
USULAN PERANCANGAN BUSINESS MODEL CANVAS PADA IKM BAROKAH DI KOTA BANDUNG
Perkembangan industri membawa pengaruh yang sangat besar terhadap
perkembangan perekonomian Indonesia, industri juga memegang peranan yang
menentukan dalam perkembangan perekonomian sehingga benar-benar perlu
didukung dan diupayakan perkembangannya. IKM Barokah merupakan suatu
usaha keluarga yang sudah dibangun dan dijalankan sejak tahun 90-an. Usaha
ini memproduksi tempe dengan berbagai macam varian.
Permasalahan yang dihadapi IKM Barokah dalam menjalankan usahanya
diantaranya yaitu lemahnya jaringan usaha dan penetrasi pasar, kurangnya
permodalan dan terbatasnya akses pembiayaan, kurangnya aliran dalam
menjangkau konsumen, sulit dalam mendapatkan pemasok bahan baku, dan
tingkat penjualan yang tidak stabil.
Penelitian yang dilakukan menggunakan format penelitian deskriptif
dengan menggunakan pendekatan kualitatif. Sumber data yang digunakan ada
dua yaitu data primer dan data sekunder. Prosedur pengumpulan data yang
digunakan adalah wawancara, observasi langsung dan dokumentasi.
Setelah melakukan perancangan business model canvas eksisting
selanjutnya menganalisis hasil rancangan tersebut dengan menggunakan analisis
SWOT. Hasil dari analisis SWOT menunjukan bahwa alternatif strategi berada
pada kuadran I (Strategi S.O) atau strategi umum yang dapat dilakukan oleh
perusahaan dengan cara menggunakan kekuatan perusahaan untuk mengambil
setiap keunggulan pada kesempatan yang ada. Hasil dari desain ulang business
model canvas IKM Barokah adalah menambah segmen konsumen, meningkatkan
kapasitas produksi, menambah channels, dan meningkatkan hubungan pelanggan
melalui delivery order.
Kata Kunci : Model Bisnis, Business Model Canvas, analisis SWO
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