bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Hydroformylation Reaction
Authors: Ojima Iwao , Tsai Chung‐Ying , Tzamarioudaki Maria , Bonafoux Dominique 
Published: April 2004

AbstractThe reaction of 1‐alkenes with carbon monoxide and hydrogen in the presence of a catalyst gives the corresponding homologous aldehydes. The discovery of this reaction was made by Roelen in 1938 using Co2(CO)8as the catalyst at high temperature (120–170°) and high pressure of carbon monoxide/hydrogen (200–300 bar). This reaction has been called the “Oxo reaction”, “Roelen reaction” or “hydroformylation”. Hydroformylation is a general term indicating that both a hydrogen and a formyl group are introduced to unsaturated bonds, especially olefins.Later this reaction was developed as an industrial process, i.e., the Oxo Process, for the production of alkanals from 1‐alkenes using a cobalt or rhodium catalyst. Most noteworthy is the conversion of propene to butanal, which can be subsequently hydrogenated to 1‐butanol or converted to 2‐ethylhexanol by self‐aldol condensation. 2‐Ethylhexanol, a crucial intermediate for the production of ester‐type plasticizers, is the most important bulk chemical produced by the Oxo Process. A variety of transition metal catalysts other than Co2(CO)8have been investigated, including phosphine complexes of cobalt and hydridocobalt clusters. Platinum and ruthenium complexes show reasonably good catalytic activities, but modified cobalt catalysts are still much more advantageous. However, various rhodium complexes demonstrate higher catalytic activity (103–104times) than the cobalt complexes. Although the price of rhodium is higher than cobalt, reactions using rhodium catalysts require lower temperature (50–80°) and pressure (10–50 atm).Other important commercial applications of hydroformylation include the production of long‐chain alcohols from C5–C17isomeric linear alkenes. These long‐chain alcohols serve as intermediates for lubricants, plasticizers and detergents. The hydroformylation of ethene to propanal is another important Oxo Process.In this chapter, the authors put clear emphasis on the scope of the hydroformylation reaction in organic synthesis. In this context, there is a relevant review in 1987 of the hydroformylation of functionalized alkenes. The hydroformylation reaction now can be performed under very mild conditions using a variety of functionalized alkenes. Reactions in aqueous biphase, supercritical carbon dioxide or fluorous biphase have recently emerged in response to separation and environmental issues. In fact, a highly efficient Oxo Process using a water‐soluble rhodium catalyst in aqueous biphasic conditions has been commercialized by Ruhrchemie/Rhône‐Poulenc for the production of butanal. Asymmetric hydroformylation of prochiral olefins catalyzed by enantiopure rhodium complexes has been developed to the level that practical applications appear possible. Although the reactions of formaldehyde, oxiranes, and others with carbon monoxide and hydrogen in the presence of transition metal catalyst could be considered as variations of hydroformylation, this chapter only deals with hydroformylation of carbon‐carbon multiple bonds.
Simmons‐Smith Cyclopropanation Reaction
Authors: Charette André B. , Beauchemin André 
Published: April 2004

AbstractAlmost 30 years after Emschwiller prepared IZnCH2I, Simmons and Smith discovered that the reagent formed by mixing a zinc‐copper couple with CH2I2in ether could be used for the stereospecific conversion of alkenes to cyclopropanes. Nowadays, the Simmons‐Smith cyclopropanation reaction is one of the most widely used reactions in the organic chemist's arsenal for the conversion of olefins into cyclopropanes. This popularity is mainly due to the stereospecificity of the reaction with respect to the double bond geometry and its compatibility with a wide range of functional groups. The chemoselectivity of the reaction toward some olefins is excellent and very few side reactions are observed with functionalized substrates. The metal carbenoid is electrophilic in nature and electron‐rich alkenes usually react much faster than electron‐poor alkenes.Furthermore, the ability to use proximal hydroxy or ether groups to dictate the stereochemical outcome of the CC bond forming process was recognized early on, and this unique property has been successfully exploited on numerous occasions. It has been recognized that halomethylmetal reagents are powerful synthetic tools for the stereoselective addition of a methylene unit to chiral acyclic allylic alcohols and allylic ethers. In addition, the use of halomethylzinc reagents in the presence of chiral additives is one of the few ways to cyclopropanate allylic alcohols efficiently and with good enantiocontrol.Carbenoids can be divided into the following two classes: (1) those of general structure MCH2X and (2) those corresponding to M = CH2. This chapter is focussed exclusively on the first class in which M = Zn, Sm, or Al. Although other metal carbenoids of type MCH2X, such as those derived from Cu, Cd, Hg, and In, have been reported to be effective reagents for the cyclopropanation of some olefins, they have been used only sporadically, and this review does not highlight these reactions. This chapter covers cyclopropanation reactions involving haloalkylzinc, aluminum, and samarium reagents published since the comprehensive chapter inOrganic Reactionsby Simmons that surveyed the literature up to 1973.
Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents
Authors: Baxter Ellen W. , Reitz Allen B. 
Published: April 2004

AbstractReductive amination is an important tool for synthetic organic chemists in the construction of carbon‐nitrogen bonds. This reaction, also termed reductive alkylation, involves condensation of an aldehyde or ketone with an amine in the presence of a reducing agent. A wide variety of substrates can be used including aliphatic and aromatic aldehydes and ketones, and even benzophenones. A range of amines from ammonia to aromatic amines, including those with electron‐withdrawing substituents, can be employed. For particularly sluggish reactions, such as those involving weakly electrophilic carbonyl groups, poorly nucleophilic amines, or sterically congested reactive centers, additives such as molecular sieves or Lewis acids are often useful.This chapter focuses on those conditions in which the carbonyl component, amine, and reducing reagent react in the same vessel. This review is restricted to reductive aminations using borohydride and borane reducing agents. This chapter concentrates on reductive amination chemistry mediated by borohydride and other boron‐containing reducing agents from 1971, the year when sodium cyanoborohydride was introduced, through the middle of 1999. In addition to reductive aminations of aldehyde and ketone substrates, reactions of related structures including acetals, aminals, ketals, carboxylic acids, nitriles, and dicarbonyls that form a nitrogen‐containing ring are reviewed. Intramolecular processes in which the substrate contains both the carbonyl and amine moieties are described. The intramolecular variant is a useful method for preparing cyclic amines. All of the various boron‐containing hydride sources in reductive aminations, including labeled metal hydrides, are reviewed. Instances of reductive aminations that failed are described. Applications of this method to a solid support in parallel synthesis in combinatorial chemistry as well as reductive aminations that proceed in tandem with a second reaction such as reductive lactamizations are discussed.
Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives
Authors: Ferrier Robert J. , Zubkov Oleg A. 
Published: April 2004

AbstractVarious elimination procedures conducted on appropriate pyranoid and furanoid carbohydrate derivatives, especially onO‐protected glycosyl halides afford cyclic vinyl ethers which Fischer (inappropriately) named glycals. These are used extensively in general organic synthesis and for the preparation of non‐carbohydrate natural products as well as biologically important complex carbohydrates and glycoconjugates. The best known member, tri‐O‐acetyl‐D‐glucal, is normally made from tetra‐O‐acetyl‐alpha‐D‐glucopyranosyl bromide, is commercially available, and is used very frequently in this chapter to represent the family in examples of the reactions under discussion.Because of the pronounced region‐ and stereoselectivities with which their addition reactions can be conducted, glycal derivatives are of major importance in synthesis. They also, however, take part in rearrangement processes that, likewise, have proved useful for synthesis. The principal one involves nucleophilic substitution of the allylic group with allylic rearrangement and results in products having double bonds in the 2, 3 positions and new substituents at the anomeric centers. By far the simplest and most commonly used way to this conversion involves the removal of the allylic substituent of the glycal and the generation of highly resonance‐stabilized oxocarbenium ion intermediate. This may then react with nucleophiles at the anomeric center to give products as mixtures of diastereomers. Many examples and variations of this theme are described and form the major part of this chapter, but other ways are also consideredAlmost no formal mechanistic studies have been carried out on the reactions in this chapter. Categorization of mechanism required for the treatment of this topic has been done on the basis of conditions used, product identification and largely, chemical intuition.
Influence of maleic anhydride on the compatibility of thermal plasticized starch and linear low‐density polyethylene
Authors: Wang Shujun , Yu Jiugao , Yu Jinglin 
Published: April 2004

AbstractIn the presence of dicumyl peroxide, the compatibility of thermal plasticized starch/linear low‐density polyethylene (TPS/LLDPE) blends using maleic anhydride (MAH) as compatibilizer was investigated. The thermal plasticization of starch and its compatibilizing modification with LLDPE was accomplished in a single‐screw extruder at the same time. We prepared three types of blends containing different percentages of TPS and MAH. The content of MAH based on LLDPE was 0, 1, and 2 wt %, respectively. The morphology of the blends was studied by SEM. It was found that, with the addition of MAH, the blends have good interfacial adhesion and finely dispersed TPS and LLDPE phases, which is reflected in the mechanical and thermal properties of the blends. The blends containing MAH showed higher tensile strength, elongation at break, and thermal stability than those of blends without MAH. The rheologic properties of the blends demonstrated the existence of processing. Finally, the dynamic thermal mechanical analysis results indicated that, with the addition of MAH, the compatibility between TPS and LLDPE in the blends was substantially improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 686–695, 2004
Preparation and properties of waterborne polyurethane/polyaniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid blends
Authors: Kwon Ji‐Yun , Koo Young‐Seok , Kim Han‐Do 
Published: April 2004

AbstractA conductive poly(aniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid) [PANI‐D/H, yield: 32.2%, intrinsic viscosity ([η]): 1.39 dL/g, electrical conductivity: 7.3 S/cm] was synthesized by chemical oxidative polymerization from aniline‐dodecylbenzene sulfonic acid salt (A‐DS)/aniline‐hydrochloric acid salt (A‐HS) (6/4M ratio) in an aqueous system. Waterborne polyurethane (WBPU) dispersion obtained from isophorone diisocyanate/poly(tetramethylene oxide)glycol/dimethylol propionic acid/ethylene diamine/triethylene amine/water was used as a matrix polymer. The blend films of WBPU/PANI‐D/H with various weight ratios (99.9/0.1–25/75) were prepared by solution blending/casting. Effect of PANI‐D/H content on the mechanical property, dynamic mechanical property, hardness, electrical conductivity, and antistaticity of WBPU/PANI‐D/H blend films was investigated. The dynamic storage modulus and initial tensile modulus increased with increasing PANI‐D/H content up to 1 wt %, and then it was significantly decreased about the content. With increasing PANI‐D/H content, the glass transition temperature of soft segment (Tgs) and hard segment (Tgh) of WBPU/PANI‐D/H blend films were shifted a bit to lower the temperature. The tensile strength and hardness of WBPU/PANI‐D/H blend films increased a little with increasing PANI‐D/H content up to 0.5 wt %, and then it was dramatically decreased over the content. The elongation at break of WBPU/PANI‐D/H decreased with an increase in PANI‐D/H content. From these results, it was concluded that 0.5–1 wt % of PANI‐D/H was the critical concentration to reinforce those various properties of WBPU/PANI‐D/H blend films prepared in this study. The electrical conductivity of WBPU/ultrasonic treated PANI‐D/H (particle size: 0.7 μm) blend films prepared here increased from 4.0 × 10−7 to 0.33 S/cm with increasing PANI‐D/H content from 0.1 to 75 wt %. The antistatic half‐life time (τ1/2) of pure WBPU film was about 110 s. However, those of WBPU/ultrasonic treated PANI‐D/H blend films (τ1/2: 8.2–0.1 s, and almost 0 s) were found to decrease exponentially with increasing PANI‐D/H content (0.1–9 wt %, and above 9 wt %). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 700–710, 2004
Adsorption of Zn(II) by crosslinked acrylic copolymers with amine functional groups
Authors: Barsanescu Adriana , Buhaceanu Rodica , Dulman Viorica , Bunia I. , Neagu Violeta 
Published: April 2004

AbstractAdsorption of Zn(II) ions from diluted aqueous solutions by the acrylic copolymer based on ethylacrylate : acrylonitrile : divinylbenzene matrix with different crosslinking degrees and ethylenediamine and triethylenetetramine functional groups was investigated. Adsorption experiments were carried out by batch method. The effects of the pH, initial concentration of zinc, time of contact, and the crosslinking degree of the copolymers were studied. On the basis of Langmuir and Freundlich isotherms, the parameters that characterize the adsorption were determined. The maximum Zn(II) retention capacity value (500 mg g−1) was obtained for the acrylic copolymer with 2% crosslinking degree and ethylenediamine, as functional groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 803–808, 2004
New evidence derived from the discrimination of Henry and Langmuir modes parameters in glassy polymeric film revealed by the Freeze‐Purged‐Desorption method
Authors: Togawa Junya , Kobayashi Masayoshi 
Published: April 2004

AbstractThe Freeze‐Purged‐Desorption (FPD) method was developed for the experimental measurement of gas permeability coefficients as a new technique using a desorption curve of gas immobilized in polymeric films. The FPD method was effectively used to evaluate four gas permeation parameters (CD, CH, DD, and DH) of glassy polymeric films (polycarbonate and polystyrene) by using CO2. The modes of the CO2 gas desorption response curve (D‐curve) obtained were sensitively characterized by the proportion of sorption in the Henry and Langmuir modes in the polymeric films accompanied by their own gas diffusivity. A graphical analysis of the D‐curve of CO2 reasonably proposed a linear relation between the desorption rate and the sorption amount of CO2, which was strongly influenced by the kind of sorption gas, film, temperature, and other factors. The desorption rate of sorbed CO2 gas for the PC and PS films gave a characteristic straight line with an inflection point indicating a shift in the gas‐diffusion mechanism from the complex type of the Henry and the Langmuir modes to the Langmuir mode. The characteristic D‐curves obtained were graphically analyzed, and they clearly discriminated the Henry mode part and the Langmuir mode part. This discrimination process quantitatively and individually evaluated CD, CH, DD, and DH. By using the four parameters evaluated, a mathematical model to describe the D‐curve was proposed, and it consistently explained the experimental D‐curves. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 934–941, 2004
Organic–inorganic hybrid material. I. Synthesis, characterization, and thermal property of a novel polyhedral cubic silsesquioxane
Authors: Dare Enock O. , Olatunji Gabriel A. , Ogunniyi David S. 
Published: April 2004

AbstractHydrosilylation of 2‐chloroethylvinyl ether by octahydridosilsesilsesquioxane catalyzed by hexachloroplatinic acid was carried out to afford a quantitative yield of 3 in its white crystals. Thermogravimetric analysis of Si8O12(CH2CH2OCH2CH2Cl)8 3 revealed that it is reasonably thermally stable. Spectroscopic data and crystal structure were used to justify the integrity, structural and molecular connectivity of the hitherto novel compound. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 907–910, 2004
Degradability of expanded starch/PVA blends prepared using calcium carbonate as the expanding inhibitor
Authors: Park Jong‐Shin , Yang June‐Ho , Kim Dae‐Hyun , Lee Dae‐Hoon 
Published: April 2004

AbstractIn this study, expanded starch/poly(vinyl alcohol) (PVA) blends for packing material were prepared by using calcium carbonate as the expansion inhibitor to investigate the degradability and the structural and mechanical properties of expanded starch/PVA/calcium carbonate blends (ESPCs). The structure of ESPCs became more compact with increasing CaCO3 content and at least 2 parts of CaCO3 were required to obtain the sufficient inhibiting effect on the expansion. As CaCO3 content increased from 1 to 4 parts, tensile strength more than doubled from 70 to 180 KPa, while elongation at break increased about 1.5‐fold. The moduli of ESPCs also increased with increasing CaCO3 content, but they decreased continuously with exposure to UV radiation over all periods of exposure and remained in the range of 10–15 KPa after exposure for 7 weeks. The weight loss of ESPCs due to exposure to soil environment increased with exposure time and the final weight loss after the 5‐week exposure was about 25–30%. Specifically, the degradability of ESPC with 20 parts of PVA was 5% higher than that of ESPC with 30 parts of PVA. The water solubility of ESPC with 30 parts of PVA was somewhat higher than that of ESPC with 20 parts of PVA. Furthermore, most of ESPCs began to be degraded thermally at 292°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 911–919, 2004
PMMA blended and DPNR‐g‐PMMA coated DPNR and NR‐LA for dipping applications
Authors: Kovuttikulrangsie S. , Sahakaro K. , Intarakong C. , Klinpituksa P. 
Published: April 2004

AbstractDeproteinized natural rubber (DPNR) latex, prepared by digesting the protein within low‐ammonia preserved concentrated (NR‐LA) latex with alcalase enzyme at 40°C for 24 h, has the nitrogen content of 0.039 wt %. Poly(methyl methacrylate) (PMMA) and graft copolymers (DPNR‐g‐PMMA) latices were synthesized by emulsion polymerization technique for blending or coating on DPNR or NR‐LA. Their general properties of natural and synthesized latices including compounded latex were verified. The friction coefficient of a homogenous film obtained from PMMA blended DPNR or NR‐LA latex and a DPNR‐g‐PMMA coated DPNR and NR‐LA film was found to be lower than those of films prepared by using DPNR or NR‐LA latex. Furthermore, the DPNR‐g‐PMMA coated films had lower friction coefficient than those of PMMA blended films. The physical properties in terms of 300% modulus, tensile strength, and elongation at break of those rubbers were tested and confined to the ASTM 3377‐78a and ASTM 3378‐99 standards for dipping products of surgical gloves and examination gloves, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 833–844, 2004
Synthesis of poly(vinyl pyridine)–silica nanocomposites using perhydropolysilazane
Authors: Saito Reiko , Tobe Tadakuni 
Published: April 2004

AbstractPoly(2‐vinyl pyridine)/silica and poly(4‐vinyl pyridine)/silica nanocomposites were synthesized by casting of blend solutions of perhydropolysilazane and poly(2‐vinyl pyridine‐co‐2‐hydroxyethyl methacrylate) and poly(4‐vinyl pyridine‐co‐2‐hydroxyethyl methacrylate) random copolymers, respectively, and calcination of dried films at 100°C under steam. The structures of the separated phases and the thermal properties of the composites were investigated by transmission electron microscopy (TEM), DSC, and TGA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 749–757, 2004
User information‐seeking behavior in a medical Web portal environment: A preliminary study
Authors: Zhang Dongming , Zambrowicz Caroline , Zhou Hong , Roderer Nancy K. 
Published: April 2004

AbstractThe emergence of information portal systems in the past few years has led to a greatly enhanced Web‐based environment for users seeking information online. While considerable research has been conducted on user information‐seeking behavior in regular IR environments over the past decade, this paper focuses specifically on how users in a medical science and clinical setting carry out their daily information seeking through a customizable information portal system (MyWelch). We describe our initial study on analyzing Web usage data from MyWelch to see whether the results conform to the features and patterns established in current information‐seeking models, present several observations regarding user information‐seeking behavior in a portal environment, outline possible long‐term user information‐seeking patterns based on usage data, and discuss the direction of future research on user information‐seeking behavior in the MyWelch portal environment.
On the Web at home: Information seeking and Web searching in the home environment
Authors: Rieh Soo Young 
Published: April 2004

AbstractAs more people gain at‐home access to the Internet, information seeking on the Web has become embedded in everyday life. The objective of this study was to characterize the home as an information use environment and to identify a range of information seeking and Web‐search behaviors at home. Twelve Northern California residents were recruited, and the data were collected through semi‐structured at‐home interviews based on a self‐reported Search Activities Diary that subjects kept over a 3–5 day period. The data were analyzed on four levels: home environment, information seeking goals, information retrieval interaction, and search query. Findings indicated that the home, indeed, provided a distinct information use environment beyond physical setting alone in which the subjects used the Web for diverse purposes and interests. Based on the findings, the relationships among home environment, Web context, and interaction situation were identified with respect to user goals and information‐seeking behaviors.