Display omitted
•Pt(II)-related characteristics of n-heptane oxidation were studied in acetic acid.•A positional selectivity of 18% was reached for 1-heptanol among the C7 alcohols.•The role of ...Pt(II) in activating primary C(sp3)H bonds was unambiguously proven.•Sulfuric acid and acetic anhydride proved to be essential for catalyst activation.
Selective functionalization of hydrocarbons remains one of the most challenging reactions in organic chemistry. With respect to terminal CH hydroxylation, electrophilic activation by late transition metals has been considered a promising route. We report the use of Shilov-chemistry inspired Pt catalysis in acetic acid as suitable solvent for the formation of primary alcohols from long linear alkanes. By reacting n-heptane with K2PtCl4 under an oxygen atmosphere, a positional selectivity of 18% was reached for 1-heptanol among the C7 alcohols at significantly high conversion (37%). Moreover, we provide evidence for the intrinsic activity of Pt(II), along with elucidation of the role of specific additives as coordinating ligands. Both acetic anhydride (AA), initially added as protecting agent, and sulfuric acid proved to be essential to obtain an active alkane hydroxylation system; via ESI-MS Pt(AA)(OSO3H)3(H2O)+ and Pt(CH3COOH)(OSO3H)3(H2O)+ were identified in the active catalytic system. Furthermore, nonselective overoxidation originates from various side reactions, for which a reaction network is proposed. Finally, the stability of the in situ formed esters was studied in detail by recording time-dependent profiles for the decomposition of different positional isomers of n-octyl acetate, as well as of its fluorinated analogues. Altogether, these results illustrate the clear potential of the proposed concept in forming primary alcohols directly from cheap and abundant alkanes.
In the present study, a palladium‐catalyzed direct oxidative acylation through cross‐dehydrogenative coupling has been investigated, utilizing readily available primary alcohols as acylating sources. ...Overall, this oxidative coupling proceeds via three distinct transformations such as oxidation, radical formation, and cross‐coupling in one catalytic process. This protocol does not involve the assistance of a directing group or activation of the carbonyl group by any other means. Furthermore, this reaction made use of no toxic CO gas as carbonylating agent; instead, feedstock primary alcohols have been utilized as acylation source. Notably, the synthesis of benzofuranones and indenones is enabled. This strategy was also applied to the synthesis of n‐butylphthalide, fenofibrate, pitofenone, and neo‐lignan.
Palladium‐catalyzed direct oxidative acylation through cross‐dehydrogenative coupling has been demonstrated, for the synthesis of a wide varity of ketones. Readily available primary alcohols have been utilized as acylating sources. Overall, this oxidative coupling proceeds via three distinct transformations such as oxidation, radical formation and cross‐coupling in one catalytic process.
We provide a new method to source fatty alcohols from poly(ethylene) (PE) pyrolysis oil. To this end, we have developed a new one-pot process to obtain fatty alcohols from a mixture of long chain ...alkenes and alkanes (C10–C20) that is obtained from pyrolyzed PE. Hydroboration–oxidation methods with and without an isomerization step were investigated for converting all types of alkenes present in the PE pyrolysis oil to primary alcohols only, following the anti-Markovnikov rule. Our process showed 91%–98% conversion of the alkenes to alcohols in a one-pot reaction at a scale of 50 g at low temperature (10–25 °C) under ambient pressure. In addition, the efficiency of the process was confirmed by testing several types of pyrolysis oil derived from commercial waste PE where alcohol recovery reached 83%–92% based on the amount of alkenes in the PE pyrolysis oil. As fatty alcohols are commodity chemicals, our study can pave the way for converting waste plastics into high value chemicals, a welcome energy and materials saving shortcut to the specialty chemicals market.
The density (ρ), viscosity (η), and speed of sound (u) are reported for binary mixtures of N-methylpiperazine with aliphatic primary alcohols (propan-1-ol, 2-propen-1-ol, 2-propyn-1-ol) over the ...entire composition range from 303.15 K to 313.15 K and at atmospheric pressure 0.1 MPa. The excess parameters (V
E
,κ
s
E
), deviation in viscosity, and excess partial properties (
,
and
) of the components at infinite dilution were calculated from the density, speed of sound, and viscosity at experimental temperatures. All the investigated systems exhibit positive values of ∆η and ∆G
*E
and negative values of V
E
and κ
s
E
over the whole composition range. The obvious deviations attribute to the association between the primary alcohols and N-methyl piperazine molecules through the hydrogen bond of O-H· · ·N. A good agreement is obtained between excess quantities and FTIR spectroscopic data.
DFT calculations have been carried out to study the mechanism of Cu(AcO)2-catalyzed N-alkylation of amino derivatives with primary alcohols. The calculations indicate that tBuOK is necessary for the ...generation of the active catalyst from Cu(AcO)2 and that the catalytic cycle involves three sequential steps: (1) Cu-catalyzed alcohol oxidation to give the corresponding aldehyde and copper hydride, (2) aldehyde-amine condensation to generate an imine, (3) imine reduction to yield the expected N-alkylation secondary amine product and to regenerate the active catalyst. Based on the comparison of different reaction pathways, we conclude that the outer-sphere hydrogen transfer in a stepwise manner is the most favorable pathway for both alcohol oxidation and imine reduction. Thermodynamically, alcohol oxidation and imine formation are all uphill, but imine reduction is downhill significantly, which is the driving force for the catalytic transformation. Using the energetic span model, we find that the turnover frequency-determining transition state (TDTS) and the turnover frequency-determining intermediate (TDI) are the hydride transfer transition state for imine reduction and the active catalyst, respectively. The calculated turnover frequency (TOF) roughly agrees with the experimental observation and, therefore, further supports the validity of the proposed hydrogen transfer mechanism.
Explosion characteristics of five alcohol–air (ethanol, 1-butanol, 1-pentanol, 2-pentanol and 3-pentanol) mixtures were experimentally conducted in an isochoric chamber over wide ranges of initial ...temperature and pressure. The effect of temperature and pressure on the different explosion behaviors among these alcohols with various structures were investigated. Results show that the peak explosion pressure is increased with the decrease of temperature and increase of pressure. Maximum rate of pressure rise is insensitive to the temperature variation while it significantly increases with the increase of initial pressure. Among the 1-, 2-, and 3-pentanol–air mixtures, 1-pentanol has the highest values in peak explosion pressure and maximum rate of pressure rise and 2-pentanol gives the lowest values at the initial pressure of 0.1 MPa. These differences tend to be decreased with the increase of initial pressure. Among the three primary alcohol–air (ethanol, 1-butanol and 1-pentanol) mixtures, a similar explosion behavior is presented at the lean mixture side because of the combined effect of adiabtic temperature and flame propagation speed. At the rich mixture side, 1-pentanol gives the highest values in peak explosion pressure and maximum rate of pressure rise and ethanol gives the lowest values. This phenomenon can be interpretated from the combining influence of heat release and heat loss, since the flame speeds of ethanol-, 1-butanol-, 1-pentanol–air mixtures are close at rich mixture side.
•Explosion characteristics of pentanol isomers were studied.•Effects of temperature and pressure on explosion characteristics were clarified.•Deflagration index and combustion parameters were provided.•Safety evaluation on pentanol isomers was made.
The work herein presents comprehensive analyses of the cuticular wax mixtures covering the flag leaf blade and peduncle of bread wheat (Triticum aestivum) cv. Bethlehem. Overall, Gas ...Chromatography-Mass Spectrometry and Flame Ionization Detection revealed a wax coverage of flag leaf blades (16 μg/cm2) a third that of peduncles (49 μg/cm2). Flag leaf blade wax was dominated by 1-alkanols, while peduncle wax contained primarily β-diketone and hydroxy-β-diketones, thus suggesting differential regulation of the acyl reduction and β-diketone biosynthetic pathways in the two analyzed organs. The characteristic chain length distributions of the various wax compound classes are discussed in light of their individual biosynthetic pathways and biosynthetic relationships between classes. Along with previously reported wheat wax compound classes (fatty acids, 1-alkanols, 1-alkanol esters, aldehydes, alkanes, β-diketone, hydroxy-β-diketones, alkylresorcinols and methyl alkylresorcinols), esters of 2-alkanols and three types of aromatic esters (benzyl, phenethyl and p-hydroxyphenethyl) are also reported. In particular, 2-heptanol esters were identified. Detailed analyses of the isomer distributions within 1-alkanol and 2-alkanol ester homologs revealed distinct patterns of esterified acids and alcohols, suggesting several wax ester synthases with very different substrate preferences in both wheat organs. Terpenoids, including two terpenoid esters, were present only in peduncle wax.
Flag leaf and peduncle waxes of Triticum aestivum cv. Bethlehem contained aliphatic, aromatic, and alicyclic compound classes with characteristic chain length and isomer distributions. Benzyl, phenethyl, p-hydroxyphenthyl, and 2-alkanol esters were found present in wheat wax. Display omitted
•14 compound classes comprising over 100 structures (including isomers) were identified and quantified.•The chain length profiles of all classes were determined and analyzed in light of biosynthetic pathways.•Four classes of esters previously unreported in wheat wax comprised 2-alkyl, benzyl, phenethyl and hydroxyphenethyl alcohols.•Metamer compositions of 1- and 2-alkanol esters were determined and found to comprise 2-heptanol.•Alkylresorcinols and methyl alkylresorcinols included the previously unreported C29 homologs.
For the first time, 2,2-bis(aminoethyl)propane-1,3-diamine (BAPDA) modified graphene oxide was prepared and lanthanum oxide nanoparticles were anchored on the multi amine-functionalized graphene ...oxide. It was demonstrated that BAPDA was effective in the size, dispersity, metal loading capacity, activity, and reusability of the final catalyst. After full characterization of the morphological, chemical, and physical structure of the catalyst (La/BAPDA-GO), the catalytic activity was investigated for the synthesis of nitriles from alcohols and aldehydes. Various aromatic and aliphatic nitriles were obtained in high yields under aqueous conditions and O
2
was the oxidant. The La/BAPDA-GO catalyst was stable and could recycle for 8 successful runs without significant loss of catalytic activity.
Display omitted
•The catalysts were prepared by reduction method at room temperature.•α-Alkylation of ketones and primary alcohols occurred on Au-Pd/CeO2 in visible light.•Superior catalytic ...activities were shown on bimetallic Au-Pd/CeO2 catalysts.•The catalyst can be reused for 4 times.•The mechanism of the synthesis for ketones was proposed.
The direct α-alkylation of ketones with primary alcohols to obtain the corresponding saturated coupled ketones was achieved with bimetallic gold(Au)-palladium(Pd) nanoparticles(NPs) supported on a transition metal oxide (such as CeO2). This system demonstrated a higher catalytic property than Au/CeO2 and Pd/CeO2 under visible light irradiation at 40±3°C in an Ar atmosphere. Such phenomenon was caused by the synergistic effect between Au and Pd. Isopropyl alcohol was used as the solvent and CH3ONa as the base. The effect of the bimetallic Au-Pd mass ratio and the two different transition metal oxide supports (such as CeO2 or ZrO2) during the reaction process was studied. The highest catalytic activity of those examined happened with the 1.5wt% Au-1.5wt% Pd (Au and Pd mass ratio 1:1)/CeO2 photo-catalyst. The intensity and wavelength of the visible light had a strong influence on the system. The catalyst can be reused for four times. A reaction mechanism was proposed for the α-alkylation of ketones with primary alcohols.
The efficient iron‐catalyzed direct β‐alkylation of secondary alcohols with primary alcohols is described. In the presence of the commercially available iron catalyst (ferrocenecarboxaldehyde, 1b) ...and a catalytic amount of base, the reactions give β‐alkylated higher alcohols in high yields in the absence of any sacrificial agents (hydrogen acceptors or hydrogen donors) and nitrogen or phosphorus ligands. For the first time, iron is employed as an inexpensive and environmentally benign alternative with high atom efficiency to noble metal‐based catalysts in this type of reaction.
PDF
