Catalytic ethoxylation of phenol and phenol derivatives

The kinetics of catalytic mono- and polyethoxylation of phenol, p-cumyl-phenol and p-isooctylphenol have been studied in the presence of strongly basic anion exchanger Wofatit SBW in hydroxy form. The influence of substituents on the rate has been investigated and the mechanism of the reaction is discussed.

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- , - Wofqtit SBW . .

     

Catalytic aziridination of olefins and amidation of thioanisole by a non-heme iron complex

A non-heme iron complex catalyses the aziridination of various olefins and the amidation of thioanisole in good yields at the expense of an aryl iodinane.     

Catalytic cyanomethylation of carbonyl compounds and imines with highly basic phosphine

A highly basic phosphine, tris(2,4,6-trimethoxy phenyl)phosphine (TTMPP), catalyzes cyanomethylation using trimethylsilylacetonitrile (TMSCH₂CN) to give the corresponding products in good to high yields, with both carbonyl compounds and imines.     

KBr催化剂上DMC与苯酚甲基化合成苯甲醚的反应机理研究

结合原位FT-IR,热力学分析及反应规律研究了KBr催化剂上碳酸二甲酯（DMC）氧位甲基化苯酚合成苯甲醚的反应机理。FT-IR显示KBr催化剂高于100℃活化苯酚生成酚盐,但至200℃也不活化DMC。共吸附的FT-IR及反应数据均显示苯甲醚高于150℃时生成。反应中检测到少量羰基甲氧基化产物苯基甲基碳酸酯（MPC）先于苯甲醚而生成,结合热力学计算及MPC分解转化的实验结果分析,生成MPC的反应是与生成苯甲醚的甲基化反应并行的可逆副反应。甲基化反应的机理为苯酚先被去质子化而形成酚盐,高于150℃时,酚盐的酚氧负离子亲核进攻DMC的甲基碳而生成苯甲醚。     

Catalytic methylation of phenol

Attempt was made to methylate phenol with methyl formate in the presence of a zeolite-supported palladium and a ruthenium-titanium catalyst.     

Highly selective metal mediated ortho-alkylation of phenol. First platinum containing organometallic chromane analogues

We were able, for the first time, to synthesize and characterize Pt derivatives with a structural shape similar to vitamin E, having a metalla-chromane core. The formation reaction mechanism includes an unexpected highly selective ortho aromatic electrophilic substitution on phenol, operated by [PtCl(eta(1)-C(2)H(4)OR)(N-N)], R = Me or Ph, and a final cyclization step. The X-ray structure of one of the new metalla-chromane complexes [Pt(EtPh)(phen)],1a, (EtPh = 2-(ethan-2'-yl-kC(1))-1-phenolato-k0(1), phen = 1,10-phenanthroline) is reported. Cytotoxicity and Pt uptake measurements, performed on HeLa cancer cells, show an interesting structure-activity correlation for the new metalla-chromane analogues 1a and [Pt(MeOEtPh)(phen)], 1b, (MeOEtPh = 2-(ethan-2'-yl-kC(1))-4-(methoxy)-1-phenolato-k0(1)), being the structurally closest to vitamin E and also the most active.     

Catalytic asymmetric carbalkoxyallylation of imines with the chiral bis-pi-allylpalladium complex

Carbethoxyallylstannane was employed along with the bis-pi-allylpalladium complex to achieve a useful conversion of prochiral imines to chiral 2-(2-aryl-2-aminoethyl)acrylates which are important building blocks for further asymmetric synthesis of a wide range of compounds.     

The selective reductive acylation of a-keto imines

Reaction of α-keto imines with the $\text{in}$$\text{situ}$ generated acetylcobalt tetracarbonyl occurs only at the carbon—nitrogen double bond to give β-keto amides. An unexpected by-product was formed in several instances.     

Catalytic, asymmetric aza-Baylis-Hillman reaction of N-sulfonated imines with activated olefins by quinidine-derived chiral amines

The chiral nitrogen Lewis base, tricyclic cinchona alkaloid derivative TQO, is an effective promoter in the catalytic, asymmetric aza‐Baylis–Hillman reaction of N‐sulfonated imines Ar? CH?NR′ 1 (R′ = Ts, Ms, Ns, SES) with various activated olefins such as methyl vinyl ketone (MVK), ethyl vinyl ketone (EVK), acrolein, methyl acrylate, phenyl acrylate, or α‐naphthyl acrylate to give the corresponding adducts in moderate to good yields with good to high ee (up to 99 %) at ?30 °C or 45 °C in various solvents, including DMF/MeCN (1:1, v/v). The first such reaction of 1 with the simplest Michael acceptor MVK and methyl acrylate has been achieved with excellent enantioselectivity. The adducts derived from MVK and EVK had the opposite absolute configuration to those from acrolein, methyl acrylate, phenyl acrylate, and α‐naphthyl acrylate. A plausible mechanism has been proposed on the basis of previous reports and the authors’ investigations. An effective bifunctional chiral nitrogen Lewis base–Brønsted acid system has been revealed in this type of aza‐Baylis–Hillman reaction.     

Fundamental studies on the development of lignin-based adhesives, I. Catalytic demethylation of anisole with molecular oxygen

In the presence of a catalyst consisting of metal-porphyrin complex and a reductant, anisole was converted into phenol by molecular oxygen at room temperature with a total turnover of the catalyst of about 70 times in 24 h.     

Catalytic alkylation of phenol with methanol over zinc aluminate

Two samples (A and B) of zinc aluminate spinel were prepared and used as catalysts of phenol methylation. Both catalysts were synthesised at hydrothermal conditions from zinc acetate and from various aluminium precursors: aluminium isopropoxide (catalyst A) or basic aluminium nitrate (catalyst B). Catalyst A was pure ZnAl₂O₄ and B - besides ZnAl₂O4 contained traces of -Al₂O₃. Reactions of phenol alkylation with methanol were carried out in the gas phase under atmospheric pressure in a standard flow reactor with fixed bed. Catalysts indicated different properties in dependence on the aluminium precursor used during preparation. In the presence of catalyst A higher selectivity of ortho-methylation of phenol was obtained. Catalyst B was active both in O-alkylation and C-alkylation.     

氧化铝负载催化剂作用下以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚(英文)

苯甲醚作为重要的化学品和医药中间体而广泛应用于香料、调味剂及有机合成.液相法是传统的苯甲醚制备工艺,例如在碱性环境下,通过酚钠与硫酸二甲酯反应,溴苯与甲醇反应,酚钠与氯代甲烷反应均可制得苯甲醚.然而,这些方法具有环境处理负担较重和所用原料毒性较强等不足而备受限制.因此,环境友好的绿色苯甲醚合成工艺的开发成为必然,苯酚的气相烷基化工艺由此提出.其中,以碳酸二甲酯(DMC)为烷基化试剂的苯酚气相转化苯甲醚制备方法最受关注.DMC是常用的绿色高效烷基化试剂,但其价格相对较高,在一定程度上增加了苯甲醚制备工艺的复杂性和产品成本.鉴于DMC可由甲醇经氧化羰基化制得,因此以甲醇为烷基化试剂的苯酚气相烷基化转化制备苯甲醚方法成为另一研究热点.然而,与DMC的烷基化性能相比,以甲醇为烷基化试剂的反应产物分布较为复杂,作为苯酚O-烷基化(在苯酚的羟基氧原子上发生的烷基化)产物的苯甲醚相对较难获得,而苯酚的C-烷基化(在苯酚的芳环上发生的烷基化)产物甲基酚产率更易提高.总体而言,与DMC烷基化方法相比,以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚方法有待改善,相关反应机理也更欠明晰,因此具有重要的研究价值.本文研究了γ-Al_2O_3(AA)负载型催化剂上以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚方法,考察了反应温度、气体空速、苯酚与甲醇配比以及催化剂中K负载量和焙烧温度等对反应性能的影响,并分析了该体系中的反应机理.研究表明,在AA上负载的8种化合物(NaCl,MgCl_2,Fe_2(SO_4)_3,Co(NO_3)_2,ZnCl_2,La(NO_3)_3,Ce(NO_3)_3和KH_2PO_4)的催化剂中,KH_2PO_4/AA的催化性能最佳,相应催化剂中K离子负载量为7.53 wt%,于700 oC焙烧8 h.苯酚与甲醇气相反应过程中,苯甲醚最大收率出现在400–450 oC,且随甲醇与苯酚的摩尔比升高而增加,但随空速的提高而降低.另外,在KH_2PO_4/AA催化剂的高K含量,以及低温、高空速、低甲醇含量的物料配比的条件下,对苯酚的O-烷基化过程有利.产物除主产物苯甲醚以外,还有少量甲基苯酚、甲基苯甲醚以及二甲基苯酚等副产物.在K含量为7.53 wt%的KH_2PO_4/AA催化剂作用下,苯甲醚收率最高时反应条件为400–450 oC,空速小于0.18 h儃1,甲醇与苯酚摩尔配比为5.本文所开发的催化剂制备方法简单,反应条件温和,产物收率较高,因此具有较好的应用前景.X射线衍射结果显示,经高温焙烧及固相反应后,KH_2PO_4/AA催化剂中产生了K_3Al_2(PO_4)_3新物相.推测该反应机理是酸性氧化铝促进甲醇脱羟基负离子以及K离子促进酚羟基脱氢质子,所形成的甲基正离子进一步与苯氧基负离子结合得到苯甲醚的"钾离子-酸"双功能催化作用过程     

Catalytic conversion of benzene to phenol

Phenol is very useful intermediate in the manufacture of petrochemicals, drugs, agrochemicals, and plastics. Commercially, phenol is produced by a three-step, high-energy consumption process known as the cumene process. The conversion of a chemical to a value-added product is always economically desirable. More than 90% of phenol consumption in the world is manufactured by the multistep cumene process, in which acetone is coproduced in 1: 1 molar ratio with respect to phenol. However, the drawbacks of the three-step cumene process have spurred the development of more economical routes to decrease energy consumption, avoid the formation of explosive cumene hydroperoxide, and increase the yield. The objective of this article is to highlight benzene-to-phenol conversion technologies with emphasis on direct conversion methods. Gas phase and liquid phase reactions are the two main routes for direct oxidation of benzene to phenol. Indirect methods, such as the cumene process, and direct methods of benzene-to-phenol conversion are discussed in detail. Also discussed is the single-step reaction of benzene to phenol using oxidants such as O₂, N₂O, and H₂O₂. Catalytic conversion of benzene to value-added phenol using a chemically converted graphene-based catalyst, a cost-effective carbon material, is discussed.