The document discusses atom transfer radical polymerization (ATRP), a controlled radical polymerization technique. It introduces ATRP and compares it to conventional radical polymerization. The key aspects of ATRP are that it uses reversible deactivation to control the number of active radicals and extend polymer chain lifetimes. This allows for precise control over molecular weight and narrow molecular weight distributions. The document outlines the basic components and mechanism of ATRP, including monomers, initiators, catalysts, ligands, and solvents. It also discusses how ATRP can be used to synthesize block copolymers and other polymer architectures.
This document provides an overview of controlled radical polymerization (CRP) techniques, with a focus on reversible addition-fragmentation chain transfer (RAFT) polymerization. It compares conventional radical polymerization to CRP, outlines the RAFT mechanism, and discusses outcomes of RAFT including control over molecular weight and architecture. The RAFT process utilizes a RAFT agent during free radical polymerization to extend chain lifetimes and enable living polymer characteristics like well-defined polymers with narrow molecular weight distributions.
Atom transfer radical polymerization (ATRP) is a controlled radical polymerization technique that involves a reversible redox process using an organic halide initiator and transition metal catalyst. In ATRP, the metal center undergoes reversible electron transfer with the halide initiator to generate reactive radicals for polymerization while maintaining a low radical concentration for control. This allows for the synthesis of polymers with narrow molecular weight distributions. ATRP can produce various copolymer architectures like block, graft, and star copolymers through appropriate initiator and monomer sequencing.
Nitroxide mediated polymerization is a controlled radical polymerization technique that uses stable nitroxide radicals. It allows high control over polymer architecture and properties. The principle involves reversible trapping of propagating radicals by nitroxide to form alkoxyamines. This prevents irreversible radical termination. Nitroxide mediated polymerization can be used to synthesize homopolymers, random/block copolymers, and functionalized polymers with applications in coatings, adhesives, and biomaterials.
This document discusses crystallinity and factors that affect crystallizability in polymers. It defines crystalline and amorphous solids, and explains that polymers exist as both crystalline and amorphous regions. Crystallinity refers to the amount of crystalline regions relative to amorphous regions. Crystallizability is the maximum crystallinity achievable at a given temperature. Factors that affect crystallizability include the polymer's molecular structure, molecular weight, branching, cis/trans configuration, homo- or co-polymer composition, polarity, and presence of bulky side groups. Homopolymers with linear and alternating structures tend to be more crystalline, while randomness, branching, and bulky groups inhibit crystallization.
Polymers are large molecules composed of many repeating structural units. The three main types of polymerization are addition, condensation, and insertion. Addition polymerization involves chain growth where a monomer adds to the end of the growing polymer chain. Condensation polymerization involves step growth where two monomers combine by removing a small molecule. Free radical polymerization is a common type of addition polymerization that uses an initiator to generate free radicals to start the chain reaction.
The document summarizes various mechanisms of polymerization, including chain-growth polymerization, step-growth polymerization, radical polymerization, cationic polymerization, anionic polymerization, coordination polymerization, Ziegler-Natta catalysis, ring-opening polymerization, and the polymerization of cyclic ethers, cyclic amides, and siloxanes. It discusses reaction initiation, mechanisms, applications, and stereochemistry for different polymerization methods.
CHAPTER 9: Kinetics of chain and step growth polymerizationJacob Adrian
This document provides an outline and overview of step-growth and chain-growth polymerization mechanisms and kinetics. It discusses the step-growth mechanism, kinetics of step-growth polymerization using Carother's equation, and controlling molecular weight. It then covers the chain-growth mechanism, kinetics of chain-growth polymerization using steady-state kinetics, and examples of free radical polymerization initiation, propagation and termination reactions. Major classes of natural and commercial polymers are also briefly mentioned.
This document provides an overview of controlled radical polymerization (CRP) techniques, with a focus on reversible addition-fragmentation chain transfer (RAFT) polymerization. It compares conventional radical polymerization to CRP, outlines the RAFT mechanism, and discusses outcomes of RAFT including control over molecular weight and architecture. The RAFT process utilizes a RAFT agent during free radical polymerization to extend chain lifetimes and enable living polymer characteristics like well-defined polymers with narrow molecular weight distributions.
Atom transfer radical polymerization (ATRP) is a controlled radical polymerization technique that involves a reversible redox process using an organic halide initiator and transition metal catalyst. In ATRP, the metal center undergoes reversible electron transfer with the halide initiator to generate reactive radicals for polymerization while maintaining a low radical concentration for control. This allows for the synthesis of polymers with narrow molecular weight distributions. ATRP can produce various copolymer architectures like block, graft, and star copolymers through appropriate initiator and monomer sequencing.
Nitroxide mediated polymerization is a controlled radical polymerization technique that uses stable nitroxide radicals. It allows high control over polymer architecture and properties. The principle involves reversible trapping of propagating radicals by nitroxide to form alkoxyamines. This prevents irreversible radical termination. Nitroxide mediated polymerization can be used to synthesize homopolymers, random/block copolymers, and functionalized polymers with applications in coatings, adhesives, and biomaterials.
This document discusses crystallinity and factors that affect crystallizability in polymers. It defines crystalline and amorphous solids, and explains that polymers exist as both crystalline and amorphous regions. Crystallinity refers to the amount of crystalline regions relative to amorphous regions. Crystallizability is the maximum crystallinity achievable at a given temperature. Factors that affect crystallizability include the polymer's molecular structure, molecular weight, branching, cis/trans configuration, homo- or co-polymer composition, polarity, and presence of bulky side groups. Homopolymers with linear and alternating structures tend to be more crystalline, while randomness, branching, and bulky groups inhibit crystallization.
Polymers are large molecules composed of many repeating structural units. The three main types of polymerization are addition, condensation, and insertion. Addition polymerization involves chain growth where a monomer adds to the end of the growing polymer chain. Condensation polymerization involves step growth where two monomers combine by removing a small molecule. Free radical polymerization is a common type of addition polymerization that uses an initiator to generate free radicals to start the chain reaction.
The document summarizes various mechanisms of polymerization, including chain-growth polymerization, step-growth polymerization, radical polymerization, cationic polymerization, anionic polymerization, coordination polymerization, Ziegler-Natta catalysis, ring-opening polymerization, and the polymerization of cyclic ethers, cyclic amides, and siloxanes. It discusses reaction initiation, mechanisms, applications, and stereochemistry for different polymerization methods.
CHAPTER 9: Kinetics of chain and step growth polymerizationJacob Adrian
This document provides an outline and overview of step-growth and chain-growth polymerization mechanisms and kinetics. It discusses the step-growth mechanism, kinetics of step-growth polymerization using Carother's equation, and controlling molecular weight. It then covers the chain-growth mechanism, kinetics of chain-growth polymerization using steady-state kinetics, and examples of free radical polymerization initiation, propagation and termination reactions. Major classes of natural and commercial polymers are also briefly mentioned.
INTRODUCTION
OBJECTIVES
METHOD OF POLYMERIZATION
FLOW DIAGRAM
MODEL OF SUSPENSION POLYMERIZATION
ADVANTAGES
DISADVANTAGES
ADVANCEMENT IN THE FIELD OFSUSPENSION POLYMERIZATION
CONCLUSION
1) Polymers are large molecules formed from the combination of small molecules called monomers through a process called polymerization.
2) Polymerization is initiated by a reactive site on a monomer that is produced using an initiator. This allows monomers to add onto a growing polymer chain.
3) Polymers are classified based on their source, thermal properties, polymerization mechanism, and structure. Some examples of polymerization mechanisms discussed are chain-growth, step-growth, free radical, anionic, and cationic polymerization.
The document discusses crystallinity in polymers. It defines crystalline and amorphous regions in polymers, and explains that polymers exist as a mixture of crystalline and amorphous phases. It describes how polymer chains fold and organize into crystalline lamellae and spherulites. The degree of crystallinity affects various material properties, and can be measured using techniques like DSC and X-ray diffraction. A higher crystallinity leads to properties like increased hardness, strength and barrier properties.
Polymer Molecular weight and its Measurement methods.pptxErozgarProfile2227
- There are several methods to measure the average molecular weight of polymers, including end-group analysis, colligative properties, light scattering, and ultracentrifugation.
- The molecular weight distribution and average molecular weights determine important properties like viscosity and processability.
- Common averages include the number-average molecular weight (Mn), weight-average molecular weight (Mw), and viscosity-average molecular weight (Mv). The ratio of Mw/Mn is called the polydispersity index (PDI).
- Techniques like end-group analysis and colligative properties work best for lower molecular weights, while light scattering and ultracentrifugation can measure wider ranges up to 100,
Methods of polymerisation It is also called as Zeigler – Natta polymerisation.
Zeigler (1953) and Natta (1955) discovered that in the presence of a combination of transition metal halides like TCl4, ZnBr3 etc, with an organometallic compound like triethyl-aluminium or trimethyl-aluminium, stereospecific polymerisation can be carried out.
Combination of metal halides and organometallic compounds are called Zeigler Natta catalyst.
The document discusses radical chain polymerization, specifically free radical polymerization. It covers the basic mechanisms of initiation, propagation, and termination in free radical polymerization as well as factors that influence these steps such as monomer structure, initiator type, and chain transfer reactions. Chain transfer reactions are described as terminating the growing polymer chain and starting a new chain. The document provides examples of different initiator types and monomers that undergo free radical polymerization.
Polymers are macromolecules built up by linking together small monomer molecules. There are two types of polymerization mechanisms: step-growth and chain-growth. Step-growth involves monomers and polymers reacting with each other, while chain-growth only involves monomers reacting with active centers on growing polymer chains. Polymers can also be classified based on their structure as linear, branched, or cross-linked, and whether they are thermoplastic or thermoset. Nomenclature of polymers involves naming them based on the monomer source, such as polyethylene from the monomer ethylene.
It consists classification of polymerization techniques. What is bulk polymerization, how will the reaction proceed, and what are the advantages, disadvantages, and applications. Similarly, what is solution polymerization and how it will be carried out, what are the advantages, disadvantages, and applications behind it everything is explained in detail. Some of the related questions are also included for practice. All the contents taken from different websites and books are also mentioned.
types of polymerization (Polymerization reactionHaseeb Ahmad
This document discusses different types of polymerization reactions including chain growth polymerization, step growth polymerization, and ionic polymerization. Chain growth polymerization involves initiation, propagation, and termination steps. Step growth polymerization involves condensation reactions between monomers to form polymers and byproducts like water. Ionic polymerization includes anionic polymerization using nucleophilic initiators and cationic polymerization using Lewis acid catalysts. Ziegler-Natta catalysis uses transition metal catalysts to polymerize monomers like propylene.
Conducting polymers are those polymers which conduct electricity due to extended P- orbital system. Due to this extension of P orbital electrons can move from one end to another end of the polymer.
Copolymerization involves polymerizing two or more different monomers simultaneously so that the resulting polymer contains more than one type of repeating unit in the polymer chain. There are several types of copolymers including random, alternating, block, and graft copolymers. The composition of a copolymer depends on factors like the monomer concentrations and their reactivity ratios. Kinetic models can be used to predict the monomer composition of the copolymer based on the monomer feed using methods like the Mayo-Lewis equation or the Fineman-Ross equation. The reactivity ratios influence whether an ideal random copolymer, alternating copolymer, or block copolymer will form. Ionic copolymerization
This document discusses fundamentals of polymer engineering, specifically polymer additives and blends. It defines additives as any substance added in small amounts to polymers to improve properties, facilitate processing, or reduce costs. Common additives include stabilizers, lubricants, fillers, plasticizers, and flame retardants. Fillers extend materials at low cost and can improve mechanical properties when well-dispersed. Polymer blends combine two or more polymers and offer benefits like extended temperature ranges, lighter weight, and improved toughness or barrier properties compared to the individual polymers. The classifications, functions, and examples of additives and blends in various polymer applications are covered in detail.
This document provides an introduction to polymer science, including definitions of key terms like polymer, monomer, oligomer, and degree of polymerization. It discusses various classifications of polymers such as by origin, monomer composition (homopolymer, copolymer), chain structure, configuration, and thermal behavior. Mechanisms of polymerization including step-growth and chain-growth are introduced. Physical properties of polymers related to their structure like crystallinity, glass transition temperature, and elastomers are also covered.
The document discusses the molecular weight of polymers. It defines molecular weight as the sum of the atomic weights of all the atoms in a polymer molecule. There are two types of average molecular weights - number average molecular weight (Mn) and weight average molecular weight (Mw). Mn is calculated by dividing the total weight of polymer molecules by the total number of molecules, while Mw takes into account that larger molecules contribute more to the total mass. Mw is always higher than Mn. Molecular weight affects various properties - higher molecular weight increases mechanical properties but lowers thermal properties. Various techniques can be used to determine molecular weight and its distribution.
Emulsion polymerization is a process where droplets of monomer are emulsified in water using surfactants. Common ingredients include 100 parts monomer, 180 parts water, 2-5 parts acid soap, and 0.1-0.5 parts water-soluble initiator. During the process, monomers inside micelles decrease as the growing polymer particle absorbs them. Unreacted monomers diffuse to other micelles and particles to continue the reaction. Polymers produced via emulsion polymerization include synthetic rubbers like styrene-butadiene rubber and plastics like polyvinyl chloride and polystyrene.
It's about Conducting Polymers their history and the latest discovery in the field with their application. And the future scope of the conducting Polymer. Here you will find all in one place.
The document discusses crystallization and crystallinity of polymers. It defines crystallinity as the degree of structural order in a solid, where the atoms or molecules are arranged in a regular, periodic manner. Crystalline polymers have long-range order arrangement of some segments of polymer chains, while amorphous polymers do not have any degree of crystallinity. Crystallinity depends on factors like length and branching of polymer chains. Methods to evaluate crystallinity include differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, and nuclear magnetic resonance. Crystallinity affects important physical properties of polymers.
Condensation polymerization involves monomers with functional groups like alcohols and carboxylic acids. During condensation polymerization, these functional groups react to form polymer chains, releasing small molecules like water or methanol as byproducts. This results in strong covalent bonds between the monomers, such as amide or ester linkages. Common examples of condensation polymerization are the reaction of a carboxylic acid and amine to form an amide linkage, or a carboxylic acid and alcohol to form an ester linkage. Condensation polymerization is an important process that allows for the production of many plastics and other materials.
This document summarizes a student's report on carbocation reaction intermediates. It introduces carbocations as positively charged carbon species that are generally unstable. The document then covers:
- Classification of primary, secondary, and tertiary carbocations
- Carbocation structure and generation mechanisms
- Factors that influence carbocation stability such as inductive effects, hyperconjugation, and resonance
- Common reactions of carbocations including combination with nucleophiles, elimination of protons, addition to unsaturated systems, and intramolecular rearrangements.
The Kumada cross-coupling reaction is a nickel or palladium catalyzed reaction between a Grignard reagent and an organic halide. The reaction proceeds through four steps - oxidative addition, transmetallation, isomerization, and reductive elimination. It is similar to other cross-coupling reactions like Negishi, Stille, Hiyama, and Suzuki reactions. The reaction exhibits cis/trans selectivity and can be made enantioselective using a chiral palladium catalyst. It has applications in synthesizing drugs like Aliskiren and materials for organic solar cells.
INTRODUCTION
OBJECTIVES
METHOD OF POLYMERIZATION
FLOW DIAGRAM
MODEL OF SUSPENSION POLYMERIZATION
ADVANTAGES
DISADVANTAGES
ADVANCEMENT IN THE FIELD OFSUSPENSION POLYMERIZATION
CONCLUSION
1) Polymers are large molecules formed from the combination of small molecules called monomers through a process called polymerization.
2) Polymerization is initiated by a reactive site on a monomer that is produced using an initiator. This allows monomers to add onto a growing polymer chain.
3) Polymers are classified based on their source, thermal properties, polymerization mechanism, and structure. Some examples of polymerization mechanisms discussed are chain-growth, step-growth, free radical, anionic, and cationic polymerization.
The document discusses crystallinity in polymers. It defines crystalline and amorphous regions in polymers, and explains that polymers exist as a mixture of crystalline and amorphous phases. It describes how polymer chains fold and organize into crystalline lamellae and spherulites. The degree of crystallinity affects various material properties, and can be measured using techniques like DSC and X-ray diffraction. A higher crystallinity leads to properties like increased hardness, strength and barrier properties.
Polymer Molecular weight and its Measurement methods.pptxErozgarProfile2227
- There are several methods to measure the average molecular weight of polymers, including end-group analysis, colligative properties, light scattering, and ultracentrifugation.
- The molecular weight distribution and average molecular weights determine important properties like viscosity and processability.
- Common averages include the number-average molecular weight (Mn), weight-average molecular weight (Mw), and viscosity-average molecular weight (Mv). The ratio of Mw/Mn is called the polydispersity index (PDI).
- Techniques like end-group analysis and colligative properties work best for lower molecular weights, while light scattering and ultracentrifugation can measure wider ranges up to 100,
Methods of polymerisation It is also called as Zeigler – Natta polymerisation.
Zeigler (1953) and Natta (1955) discovered that in the presence of a combination of transition metal halides like TCl4, ZnBr3 etc, with an organometallic compound like triethyl-aluminium or trimethyl-aluminium, stereospecific polymerisation can be carried out.
Combination of metal halides and organometallic compounds are called Zeigler Natta catalyst.
The document discusses radical chain polymerization, specifically free radical polymerization. It covers the basic mechanisms of initiation, propagation, and termination in free radical polymerization as well as factors that influence these steps such as monomer structure, initiator type, and chain transfer reactions. Chain transfer reactions are described as terminating the growing polymer chain and starting a new chain. The document provides examples of different initiator types and monomers that undergo free radical polymerization.
Polymers are macromolecules built up by linking together small monomer molecules. There are two types of polymerization mechanisms: step-growth and chain-growth. Step-growth involves monomers and polymers reacting with each other, while chain-growth only involves monomers reacting with active centers on growing polymer chains. Polymers can also be classified based on their structure as linear, branched, or cross-linked, and whether they are thermoplastic or thermoset. Nomenclature of polymers involves naming them based on the monomer source, such as polyethylene from the monomer ethylene.
It consists classification of polymerization techniques. What is bulk polymerization, how will the reaction proceed, and what are the advantages, disadvantages, and applications. Similarly, what is solution polymerization and how it will be carried out, what are the advantages, disadvantages, and applications behind it everything is explained in detail. Some of the related questions are also included for practice. All the contents taken from different websites and books are also mentioned.
types of polymerization (Polymerization reactionHaseeb Ahmad
This document discusses different types of polymerization reactions including chain growth polymerization, step growth polymerization, and ionic polymerization. Chain growth polymerization involves initiation, propagation, and termination steps. Step growth polymerization involves condensation reactions between monomers to form polymers and byproducts like water. Ionic polymerization includes anionic polymerization using nucleophilic initiators and cationic polymerization using Lewis acid catalysts. Ziegler-Natta catalysis uses transition metal catalysts to polymerize monomers like propylene.
Conducting polymers are those polymers which conduct electricity due to extended P- orbital system. Due to this extension of P orbital electrons can move from one end to another end of the polymer.
Copolymerization involves polymerizing two or more different monomers simultaneously so that the resulting polymer contains more than one type of repeating unit in the polymer chain. There are several types of copolymers including random, alternating, block, and graft copolymers. The composition of a copolymer depends on factors like the monomer concentrations and their reactivity ratios. Kinetic models can be used to predict the monomer composition of the copolymer based on the monomer feed using methods like the Mayo-Lewis equation or the Fineman-Ross equation. The reactivity ratios influence whether an ideal random copolymer, alternating copolymer, or block copolymer will form. Ionic copolymerization
This document discusses fundamentals of polymer engineering, specifically polymer additives and blends. It defines additives as any substance added in small amounts to polymers to improve properties, facilitate processing, or reduce costs. Common additives include stabilizers, lubricants, fillers, plasticizers, and flame retardants. Fillers extend materials at low cost and can improve mechanical properties when well-dispersed. Polymer blends combine two or more polymers and offer benefits like extended temperature ranges, lighter weight, and improved toughness or barrier properties compared to the individual polymers. The classifications, functions, and examples of additives and blends in various polymer applications are covered in detail.
This document provides an introduction to polymer science, including definitions of key terms like polymer, monomer, oligomer, and degree of polymerization. It discusses various classifications of polymers such as by origin, monomer composition (homopolymer, copolymer), chain structure, configuration, and thermal behavior. Mechanisms of polymerization including step-growth and chain-growth are introduced. Physical properties of polymers related to their structure like crystallinity, glass transition temperature, and elastomers are also covered.
The document discusses the molecular weight of polymers. It defines molecular weight as the sum of the atomic weights of all the atoms in a polymer molecule. There are two types of average molecular weights - number average molecular weight (Mn) and weight average molecular weight (Mw). Mn is calculated by dividing the total weight of polymer molecules by the total number of molecules, while Mw takes into account that larger molecules contribute more to the total mass. Mw is always higher than Mn. Molecular weight affects various properties - higher molecular weight increases mechanical properties but lowers thermal properties. Various techniques can be used to determine molecular weight and its distribution.
Emulsion polymerization is a process where droplets of monomer are emulsified in water using surfactants. Common ingredients include 100 parts monomer, 180 parts water, 2-5 parts acid soap, and 0.1-0.5 parts water-soluble initiator. During the process, monomers inside micelles decrease as the growing polymer particle absorbs them. Unreacted monomers diffuse to other micelles and particles to continue the reaction. Polymers produced via emulsion polymerization include synthetic rubbers like styrene-butadiene rubber and plastics like polyvinyl chloride and polystyrene.
It's about Conducting Polymers their history and the latest discovery in the field with their application. And the future scope of the conducting Polymer. Here you will find all in one place.
The document discusses crystallization and crystallinity of polymers. It defines crystallinity as the degree of structural order in a solid, where the atoms or molecules are arranged in a regular, periodic manner. Crystalline polymers have long-range order arrangement of some segments of polymer chains, while amorphous polymers do not have any degree of crystallinity. Crystallinity depends on factors like length and branching of polymer chains. Methods to evaluate crystallinity include differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, and nuclear magnetic resonance. Crystallinity affects important physical properties of polymers.
Condensation polymerization involves monomers with functional groups like alcohols and carboxylic acids. During condensation polymerization, these functional groups react to form polymer chains, releasing small molecules like water or methanol as byproducts. This results in strong covalent bonds between the monomers, such as amide or ester linkages. Common examples of condensation polymerization are the reaction of a carboxylic acid and amine to form an amide linkage, or a carboxylic acid and alcohol to form an ester linkage. Condensation polymerization is an important process that allows for the production of many plastics and other materials.
This document summarizes a student's report on carbocation reaction intermediates. It introduces carbocations as positively charged carbon species that are generally unstable. The document then covers:
- Classification of primary, secondary, and tertiary carbocations
- Carbocation structure and generation mechanisms
- Factors that influence carbocation stability such as inductive effects, hyperconjugation, and resonance
- Common reactions of carbocations including combination with nucleophiles, elimination of protons, addition to unsaturated systems, and intramolecular rearrangements.
The Kumada cross-coupling reaction is a nickel or palladium catalyzed reaction between a Grignard reagent and an organic halide. The reaction proceeds through four steps - oxidative addition, transmetallation, isomerization, and reductive elimination. It is similar to other cross-coupling reactions like Negishi, Stille, Hiyama, and Suzuki reactions. The reaction exhibits cis/trans selectivity and can be made enantioselective using a chiral palladium catalyst. It has applications in synthesizing drugs like Aliskiren and materials for organic solar cells.
The document discusses organic chemistry concepts related to radical reactions. It covers topics like radical formation, halogenation of alkanes, the reaction of radicals with sigma and pi bonds, stereochemistry of halogenation, radical chain reactions, antioxidants, and radical halogenation at allylic carbons. It also discusses chlorofluorocarbons and their role in ozone layer depletion through a radical chain mechanism.
Organometallics and Sustainable Chemistry of Pharmaceuticals.pptxKotwalBilal1
This document discusses various carbon-carbon coupling reactions, including transmetallation, Suzuki coupling, Stille coupling, and their mechanisms and applications. It provides details on:
1. Transmetallation is an organometallic reaction that transfers ligands between metals, activating a metal-carbon bond and forming a new one. It can be used in cross-coupling reactions to form C-C bonds.
2. Suzuki coupling is a cross-coupling reaction between an organoboron compound and halide catalyzed by palladium. It is widely used in pharmaceutical synthesis.
3. Stille coupling reacts an organotin compound with an organic halide catalyzed by palladium and can
Mechanisms of acid base catalysts, RNase mechanism, covalent catalysis, metal ion catalysis, Metal Ions Promote Catalysis through Charge Stabilization of enzymes. Based on Voet-Voet Biochemistry text book
The document summarizes a guest lecture on free radicals that covered several topics:
1. The structure and formation of free radicals through homolytic bond cleavage and their stability based on factors like conjugation and sterics.
2. Mechanisms of radical substitution reactions including neighboring group assistance and reactivity based on position.
3. Methods to characterize radicals using electron spin resonance spectroscopy.
4. Examples of radical reactions including halogenation, allylic substitution, and autooxidation.
This document discusses the principles and applications of atomic absorption spectrometry (AAS). It describes how AAS works by absorbing light of a specific wavelength to promote electrons in atoms to higher orbitals. It explains Beer's law that absorbance is directly proportional to concentration and path length. It also discusses instrumentation components like the light source, atomizer, detector, and applications like elemental analysis of metals in samples. The document concludes that AAS is useful for low-concentration metallic element analysis in solutions.
1) The document discusses different types of nucleophilic substitution reactions including SN1, SN2, and SNi.
2) The SN1 reaction involves the formation of a carbocation intermediate and follows a two-step mechanism. The rate determining step is the formation of the carbocation.
3) The SN2 reaction is a concerted bimolecular nucleophilic substitution that occurs in one step without an intermediate. It follows second-order kinetics.
1. Gas chromatography and liquid chromatography techniques such as HPLC are commonly used to characterize and study protein pharmaceuticals. HPLC methods like reverse phase HPLC can separate proteins based on hydrophobic interactions.
2. Other analytical techniques used include spectroscopy, electrophoresis, and mass spectrometry which provide information on protein structure, purity, quantity and degradation.
3. The selection of technique depends on the desired information and factors like resolution, sensitivity, sample requirements and throughput. Together these analytical approaches support protein quality control and characterization.
Ion pair chromatography for pharmacy studentsabhishek rai
Ion-PairChromatography
A GENERALISED OVERVIEW
Chromatography
HPLC
Reverse Phase Chromatography
Ion Pair Chromatography
Ion Pair Reagent
Mechanism of Ion Pair Chromatography
Ion Pair Wash Procedure
This document discusses the principles and instrumentation of atomic absorption spectrometry (AAS). AAS works by heating samples to atomize elements, which then absorb light at wavelengths specific to their electronic transitions. Beer's law states absorbance is proportional to concentration and path length. The instrumentation includes a light source, atomizer, detector, and data station. Flame and furnace atomizers are used to heat samples. AAS can quantitatively analyze many metals in solutions at low concentrations and has applications in fields like materials analysis and environmental testing.
Smart polymers undergo reversible physical or chemical changes in response to small environmental variations such as temperature, pH, light, or enzymes. Temperature-responsive polymers include shape-memory materials, liquid crystalline materials, and responsive polymer solutions. Polymers like poly(N-isopropylacrylamide) undergo a phase change at a lower critical solution temperature, while some exhibit an upper critical solution temperature. Photo-responsive polymers change properties like conformation or polarity when exposed to light. Magnetically-responsive polymers contain superparamagnetic iron oxide nanoparticles and change properties in the presence of a magnetic field.
This document provides an overview of catalysis by organometallic compounds. It discusses that organometallic compounds are widely used as homogeneous catalysts in industrial processes and research. Nobel Prizes have been awarded for discoveries in organometallic chemistry and homogeneous catalysis. Examples of important organometallic catalysts discussed include Wilkinson's catalyst, Noyori's catalyst for asymmetric hydrogenation, and Ziegler-Natta catalysts for polymerization of olefins. The mechanisms of homogeneous hydrogenation and different types of catalysis such as homogeneous versus heterogeneous are also summarized.
Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants. Common homogeneous catalysts include acids and bases in aqueous solutions. Homogeneous catalysts can provide selectivity in terms of chemoselectivity, regioselectivity, diastereoselectivity, and enantioselectivity. Important reaction types for homogeneous catalysis include oxidative addition, reductive elimination, migratory insertion, and β-hydride elimination. Key reactions discussed are hydrogenation, hydroformylation, hydrocyanation, and applications of Ziegler-Natta catalysts and Wilkinson's catalyst. Chiral induction with chiral ligands is also discussed for producing chiral molecules in drug synthesis such as L-DOPA
This document discusses the electrical properties of solid inorganic materials. It begins by defining solid electrolytes as crystalline solids that conduct electricity via the movement of ions. Some key solid electrolyte materials discussed include silver iodide (AgI), sodium beta-alumina, and lithium cobalt oxide (LiCoO2). Applications of solid electrolytes mentioned include use in solid oxide fuel cells, lithium-ion batteries, oxygen gas sensors, and as separators in electrochemical cells.
The document provides an overview of catalysis. It defines a catalyst as a substance that speeds up a chemical reaction but is not consumed by the reaction. It discusses different types of catalysis including homogeneous catalysis where the catalyst is in the same phase as the reactants, and heterogeneous catalysis where the catalyst is in a different phase. The document also covers catalyst characterization techniques, factors that can lead to catalyst deactivation, and methods for catalyst regeneration. Examples are provided throughout to illustrate catalysis concepts and applications.
Chapter 19 - Oxidative Phosphorylation and Photophosphorylation- BiochemistryAreej Abu Hanieh
The document discusses two processes that cells use to synthesize ATP - oxidative phosphorylation and photophosphorylation. Both processes involve the flow of electrons through electron transport chains to establish a proton gradient across a membrane. In oxidative phosphorylation, the proton gradient is used by ATP synthase to phosphorylate ADP, while in photophosphorylation light provides the energy to drive the process in chloroplasts. The chemiosmotic theory proposes that it is the flow of protons back through ATP synthase, not a direct chemical reaction, that provides the energy for ATP synthesis.
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2. Introduction
• New methods developed that allow for controlling the radical polymerization
• To minimize the monomer content and produce very uniform molecules.
• Shows 1st order kinetics
• Easy to get an exact molecular weight
• Uniformity of polymer distribution much more narrow using controlled living radical
polymerization
• The controlled comes by variety of technique SFRP, ATRP, RAFT
• Control the number of radicals reacting at any one time
2
3. Dormant species
• Formation of dormant species from propagating radical is possible by
1. Degenerative Transfer.
2. Reversible Deactivation.
3. Catalytic Reversible Deactivation.
• RDRP(ATRP,RAFT) based on reversible Deactivation of radicals were the first to be developed.
• NMP employs stable radical species, such as TEMPO to trap the propagating radicals, thus forming
dormant species which can be thermally reactivated by homolyses of the C-T(T=stable species)
bond.
• OMRP uses transition metal complexes as radical trapping agents.
3
5. Comparison between conventional and Controlled Radical Polymerization
Conventional
• The lifetime of growing chains in RP
• Initiation is slow
• Free radical initiator is often left unconsumed
• Nearly all chains are dead in RP
• Termination usually occurs between long
chains and constantly generated new chains
in RP
Controlled
• The lifetime of growing chains is extended to
more than 1 hour in CRP
• Initiation is very fast
• In CRP the proportion of dead chains is usually
of 10%.
• Polymerization in CR is slower in CRP systems,
• All chains are short at the early stages of the
reaction and become progressively longer;
thus, the termination rate significantly
decreases with time.
5
6. Why CRP
• Free radical polymerization essentially could not control MW or MWD
• Radical polymerization (RP) could not yield block copolymers due to the very short lifetime of the
growing chains
• No pure block copolymers and essentially no
• Polymers with controlled architecture can be produced by conventional RP
6
7. ATRP
• It is an example of reversible deactivation radical polymerization
• ATRP is currently the most widely used CRP technique.
• ATRP is catalytic reversible deactivation process operating at low catalyst concentration.
• A transition metal complex as the catalyst with an alkyl halide as the initiator (R-X).
• Large range of monomers polymerizable by this technique under a wide range of conditions.
• ATRP not to be considered as redox free radical polymerization, here the metal catalyst used for only radical
generation.
• In ATRP metal complex play two different role
1. Radical generation from RX/halogen capped chain end(activation)
2. Re-formation of dormant species After the short time radical propagation(deactivation).
• Various transition metals have been used in ATRP such as Cu, Ru, Fe, Ni, Os, Re, Rh, Pd, Co, Ti, and Mo.
7
8. Components of normal ATRP
• Five important variable components of atom transfer radical polymerizations
Monomer
Initiator
catalyst
ligand
Solvent
8
9. Monomer
Monomers typically used in ATRP are molecules with substituents that can stabilize the propagating radicals
for example, styrenes, (meth)acrylates, (meth)acrylamides, and acrylonitrile
Initiator
The number of growing polymer chains is determined by the initiator
low polydispersity and a controlled polymerization, the rate of initiation must be as fast or preferably faster
than the rate of propagation
All chains will be initiated in a very short period of time and will be propagated at the same rate
Alkyl halides
good molecular weight control
The shape or structure of the initiator influences polymer architecture
For example, initiators with multiple alkyl halide groups on a single core can lead to a star-like polymer
shape
α-functionalized ATRP initiators can be used to synthesize hetero-telechelic polymers with a variety of chain-
end groups
9
10. Catalyst
• The catalyst is the most important component of ATRP because it determines the equilibrium constant
between the active and dormant species
• There are several requirements for the metal catalyst:
There needs to be two accessible oxidation states that are differentiated by one electron
The metal center needs to have reasonable affinity for halogens
The coordination sphere of the metal needs to be expandable when it is oxidized as to accommodate the
halogen
The transition metal catalyst should not lead to significant side reactions, such as irreversible coupling with
the propagating radicals and catalytic radical termination
Most studied catalysts are those that include copper
10
11. Ligand
Solubilize the copper halide in whichever solvent is chosen and to adjust the redox potential of the copper
Solvents
Toluene, 1,4-dioxane, xylene, anisole, DMF, DMSO, water, methanol, acetonitrile, or even the monomer
itself (described as a bulk polymerization) are commonly used
11
13. Mechanistic aspects of ATRP
• ATRP equilibrium between active radicals and dormant species is mediated by the activator(CulL+) and
deactivator (X-CullL+)forms of the catalyst, where L=nitrogen based polydentate ligand.
• The activator CulL+ must be sufficiently active to cleave the C-X bond in the alkyl halide initiator (R-X)
• Similarly , X-CullL+ deactivator complex must quickly trap propagating radicals to generate the Pn-X dormant
species.
• The ATRP catalyst (CulL+) is subjected to both electron transfer and an atom transfer with the halogen atom
Pn-X being transferred from dormant species to the catalyst (CulL+X-CullL+) and again back to the
propagating radicals Pn-X.
• Copper catalysed ATRP occurs via an inner sphere electron transfer- concerted atom transfer (ISET-AT)
mechanism.
14. Equillibrium of ATRP:
From a thermodynamic point of view, the equilibrium of ATRP can be formly expressed as the combination of
following four contributing reaction.
1. C-X bond homolyses(BH) of the alkyl halide initiator or dormant chain, KBH
2. Electron affinity (EA)of the halogen radical, KEA
3. Reduction of the CullL2+ complex, KET
4. Association of the halide anion to the CullL2+complex, KXll
These formly the equilibrium constant of ATRP
KATRP =(KBHKEAKX
ll)/KET
1 and 2 depends upon the nature of RX.
3 only concerns the environment of the copper center (ligand and solvent)
4 depends on the nature of catalytic complex, halogen atom and solvent .
More the polar solvent and high temperature results in larger KATRP.
15. • Polydispersity index is expressed as:
D: Deactivating agent.
p: fractional conversion of monomer at any time in the reaction.
• The molecular weight distributions are narrower with lower initiator
concentrations, higher conversions, rapid deactivation (higher values of
kd and [D]), and lower kp values. When these conditions are fulfilled the
molecular weight distribution follows the Poisson distribution.
15
16. Advantages
• Increased control of molecular weight
• Molecular architecture
• Polymer composition
• Maintaining a low polydispersity (1.05-1.2)
• The halogen remaining at the end of the polymer chain after polymerization allows for facile post-
polymerization chain-end modification into different reactive functional groups.
• The use of multi-functional initiators facilitates the synthesis of lower-arm star polymers and telechelic
polymers.
• The effect of inhibitor and retarder, solvent, chain transfer agent all remain same as in convention radical
polymerization. The regioselectivity, stereoselectivity, and copolymerization behavior remain same as of
above.
16
17. Disadvantages
• Drawback of ATRP is the high concentrations of catalyst required for the reaction
• The removal of the copper from the polymer after polymerization is often tedious and expensive
• limiting ATRP’s use in the commercial sector
• A final disadvantage is the difficulty of conducting ATRP in aqueous media
Polymers synthesized through ATRP
• Polystyrene
• Poly (methyl methacrylate)
• Polyacrylamide
• ATRP polymer have green color due to the presence of copper in it which can be reduced by extraction with
water if the ligands impart water solubility to Cu2+. Cu2+ can be removed by treatment of the
polymerization reaction system with alumina.
17
19. Block Copolymer
• Statistical( random) copolymer
• Gradient copolymer
• Block & Graft copolymer
Other Architectures:
• Hyperbranched
• Brush & star
• Functionalized polymers
Block copolymer synthesized via ATRP possible by two methods:
1. One-pot sequential
2. Isolated Macroinitiator methods
20. BLOCK COPOLYMER
All Blocks via ATRP
An AB diblock copolymer is produced in the One pot sequential method by when polymerizing monomer A first
and then Monomer is added when most of the A has reacted.
In the macroinitiator method the halogen terminated monomer A (RAnX ) is isolated and than used as an initiator
(macroinitiator) together with CuX t o polymerize monomer B.
RAnX is usually isolated by precipitation with a nonsolvent or by other techniques.
Both methods requires that the polymerization of 1st monomer not to be carried to completion ,usually 90%
conversion is the maximum conversion, because the extent of bimolecular termination increases as the
concentration decreases. This would result in loss of halogen terminated chain and the corresponding loss of the
ability to propagate when the second monomer is added. The final product will be a block copolymer
contaminated with some homopolymer A.
Similarly in isolated macroinitiator case requires isolation of RAnX prior to complete conversion so that there is
minimum loss of functional group for initiation. Loss of functionality can also be minimized by adjusting the
choice and amount of component of the reaction system(activator, deactivator, solvent ligand) and reaction
condition (temperature, concentration) to minimize normal termination.
The ono pot sequential method has some disadvantage that the propagation of the second monomer involves a
mixture of second monomer plus unreacted first monomer. The second block is actually a random copolymer.
21. A symmetric block copolymer such as ABA and CABAC can be made efficiently by using a difunctional initiator
, such as α, α dichloro-p-Xylene or dimethyl 2,6- dibromoheptanedioate instead of monofunctional initiator.
Blocks via combination of ATRP and non-ATRP
One approach is to use an initiator in the non-ATRP polymerization to produce a polymer with a halogenated end
group either by initiation or termination. The halogen terminated end capped is than used as macroinitiator in
ATRP. For example cationic polymerization of styrene with 1-phynyl ethyl chloride and SnCl4,
The anionic ring opening polymerization of caprolactone with 2,2,2-tribromoethanol and triethyl aluminium and
the convention radical polymerization of vinyl acetate with a halogen containing azo compound.
Another approach is to use an initiator for ATRP that produces a polymer with functional group capable of
initiating a non- ATRP polymerization. ATRP polymerization of methyl-methacrylate with 2,2,2-tribromoethanol
produces a hydroxyl terminated poly(MMA). The OH-PMMA act as initiator in presence of triethyl aluminium
for the ring opening polymerization of caprolactone.
22. Other polymer architecture:
A star polymer contains polymer chains as arm emanating from a branch point.
Star polymers can be synthesized via ATRP by using an initiator containing 3 or more halogens for example 3arm
polymer is obtained by using a tribromo initiator:
ATRP produces a graft copolymer when the initiator is a polymer with one or more halogen-containing side
groups:
When the polymer initiator containing many halogen , there will be many grafted side chains, and the product is
called a comb or brush polymer