Chemical Research Laboratory Research Articles

Response of Nutritional and Phytochemical Constituents of Bitter Leaf to Some Drying Methods

Aim: Food processing is one of the post-harvest factors that affect the quality of food products. This research was aimed at evaluating the impact of two drying methods (sun-drying and freeze-drying) on the nutritional and phytochemical contents of Vernonia amygdalina Del.
 Study Design: Processed vegetables of V. amygdalina were subjected to the selected drying methods and the composition of the dried samples was thereafter compared.
 Place and Duration of Study: The eight-month study was carried out at the Food Chemistry Research Laboratory, Chemistry Department, The Federal University of Technology, Akure, Ondo State, Nigeria.
 Methodology: Harvested fresh samples of V. amygdalina were first cleaned with distilled water prior to drying. The dried vegetable samples were then ground to powder and subjected to proximate analysis via the application of recommended methods of Association of Official Analytical Chemists. Other nutritional and phytochemical analyses were achieved using standard methods. Independent-samples t-test was used to compare the difference in composition.
 Results: The results showed that except for crude fibre content, there was a statistical significant difference (p < 0.05) in the proximate composition of the vegetable samples obtained from the two drying methods while the freeze-drying method favoured the concentration of most of the dietary minerals tested. The two drying methods were found to give a similar phytochemicals screening result with the sun-dried samples having a higher concentration of total phenols and total flavonoids. The freeze-dried samples, however, had higher vitamin A and C contents.
 Conclusion: The research outcome revealed the suitability of the freeze-drying method for enhanced/improved drying action on vegetables and to have the optimum level of crude protein, major dietary minerals, vitamin A and C in the dried vegetables. Further work is needed to assess the impact of the selected drying methods on antinutrients composition.

Chemical safety education for the 21st century — Fostering safety information competency in chemists

During the education process, each person strives to acquire the necessary skill set or set of competencies needed to be successful in their selected career. For example, a job listing for a bench chemist might state that the successful applicant should have a BS in chemistry, (knowledge), be familiar with common laboratory operations (skills), and be a contributing member of a team (attitude). It is our job as curriculum designers and educators to give our students the competencies they will need to be successful. The chemistry curriculum must include those competencies needed for working safely in a chemistry research laboratory. This can be accomplished by weaving the knowledge component of competencies spirally into the chemistry major’s curriculum. We cannot assume that a student who has successfully completed a bachelor’s degree in chemistry has acquired the necessary competencies to perform a risk assessment or read a safety data sheet (SDS). Skill-based laboratory activity is valuable and can be specifically transferred to the next task, but knowledge and attitudes assist future learning in a nonspecific transfer and must be taught as ideas and principles. This work looks at the competencies required to be a chemist from an historical point and suggests ways that chemical safety information can be infused into the twenty-first century chemistry curriculum using embedded safety professionals, risk assessment, and SDSs to broaden and deepen safety knowledge.

Perspectives: Teaching chemists to code

Spreadsheets are a standard tool in chemistry for simple tasks such as data analysis and graphing. Chemistry students are often introduced to spreadsheets their first year of college, if not earlier, and those who continue on to do research will likely use them as a means of handling and visualizing data. Although spreadsheets have more capabilities than many people realize, they are still limited in comparison with science-specific data-analysis software applications. For example, spreadsheets are currently incapable of or not well suited for image analysis, automated data processing, high-dimensional data analysis, complex simulations, and machine learning that are needed in modern chemical research laboratories. While some educators in the chemistry community have embraced advanced data-analysis software, it’s surprising that its use isn’t more common. And going beyond that, it’s surprising that computer programming has not effectively permeated the training of undergraduate chemistry majors. The Ameri...

Real-world flexible resource profile scheduling with multiple criteria: learning scalarization functions for MIP and heuristic approaches

This article addresses a scheduling problem for a chemical research laboratory. Activities with potentially variable, non-rectangular resource allocation profiles must be scheduled on discrete renewable resources. A mixed-integer programming (MIP) formulation for the problem includes maximum time lags, custom resource allocation constraints, and multiple nonstandard objectives. We present a list scheduling heuristic that mimics the human decision maker and thus provides reference solutions. These solutions are the basis for an automated learning-based determination of coefficients for the convex combination of objectives used by the MIP and a dedicated variable neighborhood search (VNS) approach. The development of the VNS also involves the design of new neighborhood structures that prove particularly effective for the custom objectives under consideration. Relative improvements of up to 60% are achievable for isolated objectives, as demonstrated by the final computational study based on a broad spectrum of randomly generated instances of different sizes and real-world data from the company’s live system.

EKSTRAKSI DAN KARAKTERISASI INULIN DARI UMBI DAHLIA (Dahlia sp.L) SEGAR DAN DISIMPAN

Inulin is a natural polymer composed of monomers fructose, which is connected with the linear bonding ?-2,1-fruktosil-fructose. One source of inulin is the dahlia tubers (65.700%). The purpose of this study was to determine the water content, degree of purity inulin and how the value of the degree of polymerization inulin from dahlia tubers fresh and stored 4 weeks kinds of decorative strands formal crimson crown. This research was conducted experiments in Chemistry Research Laboratory UNP. The object of research was a kind of decorative dahlia tubers formal crimson obtained in the area of Aia Tawa, Kampung Batu nature, Solok. Inulin was characterized by using GC (Gas Chromatograpy) and HPLC(High-PerformanceLiquidChromtography). Determination of water content by using method of the AOAC(Associationof Official of Analytical Chemist).The results showed that the water content of dry weight percent (bk) inulin from dahlia tubers fresh is 2.123%, Inui figure is not much different than the inulin from dahlia tubers stored 4 weeks 2.003%. Based on the GC spectrum can be analyzed qualitatively that inulin extracted from dahlia tubers have a degree of polymerization of smaller than commercialinulin. Chicory Based on the spectrum of HPLC showed that inulin extracted from the tubers of dahlias has a purity level is almost the same as inulin commercial Chicory merck Fluka.

The chemical engineering research laboratory as context for graduate students' training: The role of lab structure and cultural climate in collaborative work

Abstract The current study investigated the experiences of engineering graduate students in two interdisciplinary research laboratories studying materials engineering, their perceptions of influences on their learning and goals, and the collaborative tasks needed to produce quality journal articles. In a qualitative inquiry using constant comparison methods, data came from individual interviews of lab members and observations. Findings coalesced in three themes. First, the lab structure and lines of communication seemed to influence group collaboration and individual learning. Second, the importance of peer collaboration seemed crucial to students' knowledge acquisition through lab work. Finally, a lab's climate and culture influenced individuals' productivity and motivation to participate in research, sometimes facilitating, sometimes impeding progress in becoming fully participating lab members. Contributions include providing a better understanding of how engineering graduate students' lives in the lab are situated and intertwined with group collaborative processes.

Highly active and efficient catalysts for alkoxycarbonylation of alkenes

Carbonylation reactions of alkenes constitute the most important industrial processes in homogeneous catalysis. Despite the tremendous progress in this transformation, the development of advanced catalyst systems to improve their activity and widen the range of feedstocks continues to be essential for new practical applications. Herein a palladium catalyst based on 1,2-bis((tert-butyl(pyridin-2-yl)phosphanyl)methyl)benzene L3 (pytbpx) is rationally designed and synthesized. Application of this system allows a general alkoxycarbonylation of sterically hindered and demanding olefins including all kinds of tetra-, tri- and 1,1-disubstituted alkenes as well as natural products and pharmaceuticals to the desired esters in excellent yield. Industrially relevant bulk ethylene is functionalized with high activity (TON: >1,425,000; TOF: 44,000 h−1 for initial 18 h) and selectivity (>99%). Given its generality and efficiency, we expect this catalytic system to immediately impact both the chemical industry and research laboratories by providing a practical synthetic tool for the transformation of nearly any alkene into a versatile ester product.

Effect of n-Butanol on Chromosomal Damage in Mice Bone Marrow Cells

Background: n-Butanol is a four-carbon alcohol used widely in foods, cosmetics industries, biology and chemistry research laboratories, and other fields. Long time-effects of inhalation or consumption of small amounts of Butanol on human health are still unknown. On the other hand, numerous reports about the development of n-Butanol toxicity are available. The main objective of the study was to investigate the effects of inhaled and oral administration of n-Butanol as a long-term in vivo investigation. M aterials and Methods: Small white laboratory, male mice (20-30 g) were used in 11 groups (n=4) including experimental 1 to 6, 1 to 4 control A” and positive control groups. Experimental groups 1-3, for 10, 20, and 40 days; 5 hours a day were inside a box with ventilation facilities exposed to air saturated with n-Butanol vapor. Experimental groups 4 to 6, received water containing n-Butanol 0.2%, 1% and 5% for 10 days. Control groups B, 1 to 3 was placed for 10, 20, and 40 days inside a similar box exposed to normal air, respectively. Control group B 4 received water without any particular substance for 10 days. The positive control group received 30µl subcutaneous vinblastine. Bone marrow cells were extracted 24 hours after treatments and stained by May-Grunwald-Giemsa staining and the number of micronucleus was counted. Vinblastine, as a positive control, increased an average of micronucleus numbers significantly compared to control group (P<0.001). R es ults: n-Butanol inhalation caused no significant difference in 1-3 experimental groups in the average numbers of micronucleus compared to control group, even in the 40 days treatment group, average numbers of micronucleus was decreased comparing to control group (P<0.05). Also, oral administration of 0.2% and 1% n-Butanol had no effect on the average micronucleus numbers compared to the control group, while oral administration of 5% n-Butanol caused even decrease in average numbers of micronucleus compared to control group (P<0.05). Conclusion: n-Butanol inhalation may not cause chromosome damages in rat bone marrow cells that probably is due to its very fast metabolism and decomposition in the body. Therefore, the amount of n-Butanol in the systemic circulation and tissues is very low and, probably, the damaging potential is decreased.

Off the Beaten Track-A Hitchhiker's Guide to Beryllium Chemistry.

This Minireview aims to give an introduction to beryllium chemistry for all less-experienced scientists in this field of research. Up to date information on the toxicity of beryllium and its compounds are reviewed and several basic and necessary guidelines for a safe and proper handling in modern chemical research laboratories are presented. Interesting phenomenological observations are described that are related directly to the uniqueness of this element, which are also put into historical context. Herein we combine the contributions and experiences of many scientist that work passionately in this field. We want to encourage fellow scientists to reconcile the long-standing reservations about beryllium and its compounds and motivate intense research on this spurned element. Who on earth should be able to deal with beryllium and its compounds if not chemists?

Microcontroller Based Orbital Motion Shaker

A novel procedure of controlling various environmental conditions, shaking speed and duration for shaking of liquid/ semi solid required for microbiology/ chemical research laboratories with the use microcontroller is presented in this paper. The Microcontroller monitors and controls the environmental conditions i.e. humidity, temperature and also provides selectable speed, duration of orbital motion shaker. The system consists of orbital motion producing mechanism, the enclosure for controlled conditions, instruments to control environmental conditions, feedback instruments in order to establish control and microcontroller system which provides programming, interlock and protection for conditions required. This advance microprocessor control ensures reproducible results and operator convenience. System interlocks are also provided in order as a safety measures towards samples examined or cultured by not allowing deviation from the programmed conditions. Microcontroller also ensures self correction in incubation, refrigeration or humidity controls by taking continuous feedback from field instruments. The control system becomes significant as it provides reproducibility in enzyme reactions like aeration in liquid or faster cell growth rate.

The Safety “Use Case”: Co-Developing Chemical Information Management and Laboratory Safety Skills

The 2015 edition of the American Chemical Society’s Guidelines and Evaluation Procedures for Bachelor’s Degree Programs identifies six skill sets that undergraduate chemistry programs should instill in their students. In our roles as support staff for chemistry departments at two different institutions (one a Primarily Undergraduate Institution, the other a research intensive university), we have been collaboratively studying these requirements and have found significant synergies between two in particular: “Chemical Literature and Information Management Skills” and “Laboratory Safety Skills”. We believe that by integrating emerging tools in the laboratory safety field into information literacy frameworks, a strong foundation can be established for the development of all the skills called out by the ACS. This article describes this strategy and provides examples of how these concepts can be implemented in both the chemistry teaching and research laboratory settings.

The Applications of (Para)formaldehyde in Metal‐Catalyzed Organic Synthesis

AbstractParaformaldehyde (PFA), with the chemical formula CxHyOz, an infinite solid form of formaldehyde, is a very useful reagent in classical organic reactions. Numerous applications have been explored both in the chemical industry and organic chemistry research laboratories. In this general review, we have summarized the main achievements in the use of paraformaldehyde in organic reactions with transition metals as the catalysts. In these methodologies, paraformaldehyde has been applied as methylene blocks, hydroxymethylation reagents, CO source, syngas surrogate, hydrogen donor or acceptor, formylation and methylation reagents. Additionally, in order to make this review systematic, recent reported organocatalyzed transformations of paraformaldehyde have been included as well.magnified image

An Approach To Enhance the Safety Culture of an Academic Chemistry Research Laboratory by Addressing Behavioral Factors

Safety culture is often divided into three domains, which include personal, environmental, and behavioral factors. In order to improve the behavioral components of the safety culture in the research group of the authors (the Garcia-Garibay group, or GG research group), we implemented three safety practices intended to sensitize group members on the importance of best practices that depend on simple actions taken by individual researchers. These best practices include (1) a rotating twice-daily safety inspection to enhance an appreciation for the value of safety regulations that may be considered less significant and are frequently overlooked, (2) frequent safety discussions followed by quizzes to give researchers an opportunity to assess their safety knowledge on a range of topics, and (3) the use of an overnight reaction form that is posted on lab entryways as a safety communication best practice to ensure that other researchers in the laboratory and emergency responders are aware of the potential hazard...

Carbon and important macroelements of Terric Histosol after 12 years renaturalization

The aim of this study was to determine the chemical properties of peat soil depending on changes in land-use. The Terric Histosol (HSs) was investigated in this research, and the treatments of former different land-use in Radviliskis site. Chemical analyses were carried out at the Chemical Research Laboratory of LRCAF. After 12 years since the end of field experiment the differences in soil chemical composition remained still between treatments of differently used peat soil. Due to mineralization, the content of soil organic matter (SOM) and SOC respectively decreased, the largest amounts of SOC are stored in the upper soil layer of perennial grasses fertilized with NPK (NPK), there was the highest yield of biomass; and accordingly, the lowest content of SOC – in soil of un-used peat (UU). The distribution of total N and P in profile of Terric Histosol is directly related to the vertical gradient of mineralization intensity; higher amounts of N and P have been accumulated where mineralization was more intense. The distribution of total K is related to land-use of Terric Histosol , whereas the biggest quantity of total K was established in arable land which has been fertilized with mineral fertilisers.

Zeolite-like Arabinose-based Coordination Polymers: Synthesis and Characterization for Heavy-Metal Sequestration Applications

L–Arabinose-based coordination polymers were synthesized by the oxidation of L–arabinose using warm HNO3 to form arabinaric acid and allowing the resulting arabinaric acid to react with the different metal ions such as zinc(II), lead(II), copper(II), iron(III), and chromium(III). Only zinc(II) and lead(II) ions produced crystalline coordination polymers suitable for analysis while copper(II) produced a gummy solid. Preliminary characterization of the coordination polymers was based on their solubility, melting points, UV–Visible spectra, and infrared spectra. The coordination polymers were insoluble in common organic solvents and in acidic aqueous solutions but soluble in moderately basic aqueous solutions (pH 12). The zinc(II) and lead(II) coordination polymers have melting points above 300°C while the copper(II) polymer melts from 218–225°C. UV–Visible spectra showed that these polymers have maximum absorption in the ultraviolet region. Zinc(II), lead(II), and copper(II) arabinarate coordination polymers had maximum absorbance at λmax = 217 nm, λmax = 240 nm, and λmax = 220 nm, respectively. The infrared spectra of the coordination polymers indicated the association of the arabinarate ligand with the metal ions. Introduction and incorporation of molecular species such as azobenzene and molecular iodine to the coordination polymers were also investigated. Infrared spectra obtained from the azobenzene inclusion experiments showed additional infrared absorption bands below 1000 cm –1 implying absorption of azobenzene within the polymers. Iodometric titrations also confirmed the inclusion of iodine in the coordination polymers. The potential of the coordination polymers to incorporate lead(II) ions in aqueous solutions was also investigated using column elution of different sample concentrations of lead(II). Atomic Absorption Spectrometric analysis illustrated significant lead reduction of up to 80.70 ppm of lead(II) on the eluted samples. Introduction Rapid industrialization in the modern world today causes severe pollution in the environment. This may be due to toxic, inorganic, or non-biodegradable materials released to the environment as waste products during industrial processes. Heavy metals, like lead, are among the most harmful of the environmental elemental pollutants. Lead contamination from excessive exposure has been found to cause several health hazards and long term detrimental effects. Prominent conventional processes for the removal of lead from aqueous mixtures, such as sludge separation, chemical precipitation, and electrochemical treatments are relatively expensive and can cause secondary pollutants (Manahan, 1993 as cited in Acabal et al., 2000). Due to the problems of pollution, “green” industrial productions of compounds and their derivatives based on renewable starting materials and biodegradable products are developed (Kiely, 2001). Carbohydrates are biodegradable, widely available, and generally economical. Hence, their study for chemical and industrial applications would be very sensible. Because of their ease in functionalization forming sugar derivatives, they could serve as valuable building blocks for potentially useful polymers (Abrahams et al., 2003). Heavy metal sequestering properties of certain types of these polymers provide an alternative and potentially economical treatment process for heavy metal removal and recovery.

Beyond the Balz-Schiemann reaction: the utility of tetrafluoroborates and boron trifluoride as nucleophilic fluoride sources.

ADVERTISEMENT RETURN TO ISSUEReviewNEXTBeyond the Balz–Schiemann Reaction: The Utility of Tetrafluoroborates and Boron Trifluoride as Nucleophilic Fluoride SourcesAlexander J. Cresswell, Stephen G. Davies*, Paul M. Roberts, and James E. ThomsonView Author Information Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom*E-mail: [email protected]Cite this: Chem. Rev. 2015, 115, 2, 566–611Publication Date (Web):August 1, 2014Publication History Received31 March 2014Published online1 August 2014Published inissue 28 January 2015https://doi.org/10.1021/cr5001805Copyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views9850Altmetric-Citations134LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (12 MB) Get e-AlertsSUBJECTS:Anions,Ethers,Halogenation,Hydrocarbons,Ions Get e-Alerts

Preparation of Mesoporous SBA‐16 Silica‐Supported Biscinchona Alkaloid Ligand for the Asymmetric Dihydroxylation of Olefins

Optically active cinchona alkaloid was anchored onto mesoporous SBA‐16 silica and the as‐prepared complex was used as a heterogeneous chiral ligand of osmium tetraoxide for the asymmetric dihydroxylation of olefins. The prepared catalytic system provided 90–93% yield of vicinal diol with 92–99% enantioselectivity. The ordered mesoporous SBA‐16 silica was found to be a valuable support for the cinchona alkaloid liganded osmium catalyst system which is frequently used in chemical industries and research laboratories for olefin functionalization.

A Simple Millifluidic Benchtop Reactor System for the High-Throughput Synthesis and Functionalization of Gold Nanoparticles with Different Sizes and Shapes

Despite the continuing interest in the applications of functionalized nanomaterials, the controlled and reproducible synthesis of many important functionalized nanoparticles (NPs) above the milligram scale continues to be a significant challenge. The synthesis of functionalized NPs in automated reactors provides a viable approach to circumvent some of the shortcomings of traditional nanomaterial batch syntheses, providing superior control over reagent addition, improved reproducibility, the opportunity to interface real-time product monitoring, and a viable high-throughput synthetic approach. Here, we demonstrate the construction and operation of a simple millifluidic reactor assembled entirely from commercially available components found in almost any chemical laboratory. This reactor facilitates the aqueous gram-scale synthesis of a variety of functionalized gold nanoparticles, including the synthesis of gold nanospheres with tightly controlled core diameters and gold nanorods with controlled aspect ratios between 1.5 and 4.0. The absolute dimensions (i.e., the transverse diameter) of gold nanorods synthesized within the reactor can also be tailored to produce different gold nanorod shapes, including "small" gold nanorods and gold nanocubes. In addition, we show that the reactor can interface with existing purification and monitoring techniques in order to enable the high-throughput functionalization/purification of gold nanorods and real-time monitoring of gold nanoparticle products for quality control. We anticipate that this millifluidic reactor will provide the blueprint for a versatile and portable approach to the gram-scale synthesis of monodisperse, hydrophilically functionalized metal NPs that can be realized in almost any chemistry research laboratory.

Comments on: Book Review by Peter Myers on Michael J. Sailor: Porous Silicon in Practice. Preparation, Characterization and Applications

The reviewer brings up some important points in his review of the book. The author regrets any confusion the statement from the preface ‘‘This book is written for the beginner— someone who has no prior training in the field’’ may have caused. It should be stressed that this book is intended for the beginner to the field of porous silicon, not a beginner to the field of science or research in general. The user of this book should have a solid undergraduate-level understanding of chemistry, and be well-acquainted with the hazards and safety procedures used in a modern chemistry or materials research laboratory. As the reviewer points out, HF is a hazardous chemical, and the reader should pay close attention to Sect. 2.4 (pg 48), which outlines the precautions in dealing with and disposing of HF and refers the reader to Appendix A2, titled ‘‘Safety Precautions when Working with Hydrofluoric Acid,’’ (pg 235). Appendix A2 is devoted to the safe handling of HF, including the MSDS, the health effects of HF exposure to various tissues of the body, and the need for ‘‘GOGGLES AND SHIELD; LAB COAT AND APRON; VENT HOOD; PROPER GLOVES.’’ That section also includes first aid for inhalation, ingestion, skin contact, and eye contact, and it includes directions to the physician in case an accidental exposure occurs. The fact that the reviewer appears to have missed these sections in the book suggests that others may also do so; it provides a good opportunity to stress the need for attention to the proper handling of HF and the other chemicals described in the book. In particular, setting up the reactor for the microwave-assisted hydrosilylation reaction described on pg 205 should be done in consultation with a safety specialist. The author wishes to re-emphasize that it is not appropriate to use a commercial microwave oven for such reactions—‘‘the use of a microwave reactor designed for chemical reactions, and that has adequate explosion safety protection is recommended.’’ The book provides schematics for etching and gas dosing cells in a series of appendices. The reviewer recommends that the user seek advice from a qualified engineer on the design, construction, and testing of the gas dosing cell be obtained. Indeed, as every user will have different goals, input from a qualified engineer should be sought for all of the schematics given in the book to ensure that the devices will serve their intended purpose safely and effectively. In the case of the gas dosing cell, it should be stressed that the cell described in Appendix A3 is an open, vented cell meant to be operated at atmospheric pressure. The author thanks the reviewer for his constructive comments and for emphasizing the need for adequate safety precautions when performing the experiments described in this book.

Self‐Liganded Suzuki–Miyaura Coupling for Site‐Selective Protein PEGylation

The discovery and development of palladium-catalyzed carbon–carbon bond formation has revolutionized modern organic chemistry in recent decades. The versatility and robustness of these processes have enabled major progress in total synthesis, materials development, and medicinal chemistry. Currently, a large variety of nucleophiles and electrophiles can be efficiently coupled, and part of the efforts to increase the utility of these reactions are now directed towards the development of simpler, more active, and economic catalytic systems that work under mild conditions. Owing to their broad functional-group tolerance and low associated toxicity, as well as their chemical and biological compatibility, Pd-catalyzed reactions are now attractive approaches for protein modification. These processes are particularly interesting, as a variety of non-natural amino acids can be genetically incorporated into peptides and proteins, thus providing specific chemical handles for a number of post-translational manipulations, including palladium-mediated reactions. Recent contributions from our group and others report robust and highly efficient Suzuki–Miyaura and Sonogashira cross-coupling on protein substrates bearing a halide or alkyne moiety, respectively, under ambient conditions both in vitro and on cell surfaces. As part of our continuing interest in developing chemical tools for the mild and specific post-translational modification of proteins, we investigated the use of the Suzuki–Miyaura coupling to site-selectively attach polyethylene glycol (PEG) chains to proteins. Protein PEGylation is a widespread approach to improve the stability and pharmacokinetics of protein drugs by reducing clearance rates, while providing a steric shield from proteolytic enzymes and immune system recognition. However, reduced biological activity is often observed for PEG-conjugated proteins. This effect is attributed to steric crowding resulting from the low positional control achieved with traditional PEGylation chemistry; commonly used PEG-derivatives react with the side chains of natural amino acids, such as lysines or cysteines, or protein termini and disulfide bonds. Whenmore than one reactive site is present on the protein, these approaches lead to heterogenous mixtures of potentially less-/in-active conjugates that are difficult to separate. The possibility of siteselectively PEGylating proteins could potentially overcome this problem but, to date, only a few examples use the PEGderivatization of genetically-encoded non-natural amino acids. These include Sonogashira coupling at homopropargyl-glycine, and triazole formation or Staudinger phosphite reaction at p-azidophenylalanine. The two former examples involve metal catalysts and required exogenous ligands and consequent optimization. Airand moisture-stable Pd-ligands provide convenient systems that do not require inert atmosphere or degassed solvents. Nonetheless, even more direct “ligandless” (selfliganded or lacking an added ligand) methods are of significant interest. This would provide a more straightforward method that is particularly attractive in biotechnological applications to be conducted on scale such as PEGylation. Pdnanoparticle-based catalysts and metal catalysts stabilized by polymers such as polyethylene glycol (PEG) have been reported. Taking advantage of these potential stabilizing properties of PEG, we considered the possibility of direct palladium-catalyzed PEGylation of halogenated amino acids with PEG–boronic acid derivatives in the absence of additional ligand. Herein, we report PEGylation of amino acids, peptides, and proteins through palladium-catalyzed Suzuki–Miyaura coupling of 2 kDa and 20 kDa monomethoxy PEG (mPEG) phenylboronic acids (mPEG2k-PBA and mPEG20k-PBA, respectively). An evaluation of pyrimidineor guanidinebased palladium complexes and comparison with PEG reagents alone reveals that the latter can act as potent selfliganding agents for the stabilization of metal species, thus allowing complete conversion using water-soluble palladium salts in the absence of external ligands. The resulting reaction system combines the advantages of reaction biocompatibility for protein modification with the possibility of combining a highly simple, single-component, economic, and environmentally friendly catalyst with a self-liganding coupling partner. We believe this shows the first example of ligandless metal-mediated ligation on a protein surface. Our initial study focused on the PEGylation of N-Boc-4iodo-l-phenylalanine (1; Boc-pIPhe) with mPEG20k-PBA (2) by Suzuki–Miyaura cross-coupling in 20 mm phosphate buffer, pH 8.0. The palladium catalyst system first tested used an additional ligand 2-amino-4,6-dihydroxy-pyrimidine (L1), [*] Dr. A. Dumas, C. D. Spicer, Dr. Z. Gao, Y. A. Lin, Prof. B. G. Davis Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX13TA (UK) E-mail: ben.davis@chem.ox.ac.uk