Polymers and Synthesis

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  • Created on: 23-02-15 17:20
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  • Polymers and synthesis
    • Amino Acids
      • Amino acids are the building blocks of two groups of biological molecules- peptides and proteins. Amino acids are soluble in both acids and bases.
      • Proteins act as enzymes, hormones and antibodies. Polypeptides transport substances such as oxygen, vitamins and minerals to cells throughout the body. Structural proteins, such as collagen and keratin are responsible for the formation of bones, teeth and the outer layer of skin, and they help to maintain the structure of blood vessels and other tissues.
      • The general formula of an a-amino acid is RCH(NH2)COOH. The R group can be an -OH, -SH, -COOH or -NH2 group.
      • A pH that is more acidic than the isoelectric point means that the amino acid accepts a proton and acts as a base, forming a positively charged ion. A pH which is more alkaline than the isoelectric point means that the amino acid donates a proton to the base and acts as an acid, forming a negatively charged ion.
    • Polypeptides and proteins
      • A protein or polypeptide is a long chain of amino acids joined together by peptide linkages. This is made by condensation reactions of amino acids.
      • When drawing a polypeptide, one end of the structure contains a C=O group and the other end an N-H group. Polypeptides are drawn with their ends open.
      • For each amino acid added to the chain, a molecule of water is formed. A polypeptide contains many linked amino acids. Proteins are long polypeptides.
      • Acid hydrolysis- Polypeptides and proteins are hydrolysed using aqueous acid. During this, the amino acids formed are positively charged because of the presence of H+ ions from the acid.
      • Alkaline hydrolysis- A form of aqueous sodium hydroxide is used at just above 100.C. The polypeptide or protein is broken down into amino acids in the form of their sodium salts.
    • Condensation Polymerisation- polyamides
      • In a polyamide, the monomers have a carboxyl group, -COOH, and an amine group, NH2. 1) Polyamide made by reacting a dicarboxylic acid monomer with two -COOH groups and a diamine with two -NH2 groups.
      • 2) Polyamides made by reacting one type of monomer unit containing both -COOH and -NH2 groups. Amino acids are this type of monomer. Amide linkage forms and water is eliminated
      • Kevlar is an example and it has fire resistance and has a higher strength than steel. It is used to make protective clothing.
    • Addition and condensation- polymerisation
      • Addition polymers are made from one type of monomer only and there is no product other than the polymer. Each one has their own specific properties.
      • Condensation polymers are made up of two monomers which join together to eliminate a small molecule such as water or HCl. These monomers have two functional groups in their structure.
      • How to identify the type of polymerisation- If the monomer contains a double bond, then the polymerisation is addition; if the backbone of the polymer is a continuous chain of carbon atoms, then the polymer is likely to have been made by addition and the monomer will be an alkene.
      • If there are two monomers each with two normal or different functional groups, then the polymerisation is condensation; if the polymer contains ester or amide linkages, then the polymerisation is condensation.
    • Organic synthesis of aromatic compounds
      • An ester can be made from an alcohol and a carboxylic acid; aldehydes can be oxidised to carboxylic acids and reduced to primary alcohols; and amines can be made from halogenoalkanes using excess ammonia.
    • Condensation Polymerisation- polyesters
      • Polyesters from two types of monomer units- A bond forms between a hydroxyl group on the diol and a carbonyl group on a dicarboxylic acid. An ester linkage is formed and water is eliminateed.
      • Polyesters are used in making carpets, sports clothing and shirts. In clothing and bedding, the polyesters are blended with cotton. Almost all polyesters can be machine-washed and machine-dried. It is a strong fibre which is resistant to stretching, shrinking and chemical attack. Unfortunately it burns easily and so it should not be exposed to naked flames.
      • Polyesters from one type of monomer unit- Polyesters can be formed from hydroxycarboxlic acids, which contain both -COOH and -OH groups. During condensation polymerisation, a bond forms between the hydroxyl group on one lactic acid molecule and a carboxyl group on a different lactic acid molecule. This forms an ester linkage and water is eliminated.
    • Organic synthesis of aliphatic compounds
      • How to approach organic synthesis: - A good knowledge of all chemical reactions, reagents and conditions in the specification. The starting material and the product should be checked to spot what has changed. The answer should be then checked and the equations should be balanced.
    • Chirality in pharmaceutical synthesis
      • Synthesising pharmaceuticals- Drugs and medicines act by interacting with materials such as proteins, nucleic acids and with biological systems such as cell membranes. These biological molecules have a complex 3D structure which binds to a drug molecule in only one possible way. The 3D structure determines the pharmacological activity of a drug and whether a phermaceutical will have the desired theraputic effect or not.
      • The production of a single isomer with the correct pharmacological activity presents significant advantages to pharmaceutical companies. This includes; risks from undesirable side effects are reduced and drug doses are reduced.
      • When a chiral compound is synthesised in the laboratory, a mix of optical isomers are formed, but when the same material is made naturally in a living system. it is produced as a single optical isomer.
      • To prepare a chiral compound in the lab, separation techniques are needed to isolate the pharmocologically active isomer. This is diffcult as the optical isomers usually have the same or very similar physical properties incl. melting points, boiling points and solubilities. These techniques include the use of enzymes, electrophoresis and chromatography. These are costly and take a lot of time.
      • Methods used to prepare single chiral isomers- using enzymes as biological catalysts, chiral pool synthesis and use of transition element complexes. Chiral drugs are also used at home as ibuprofen is an anti-inflammatory drug that targets both bone and muscle pain. It blocks messages to the brain and reducing swelling or inflammation. This is commonly used to relieve headaches, back pain and period pain, and to treat cold and flu symptoms and arthritis.
    • Breaking down condensation- polymers
      • Esters can be hydrolysed under acidic or basic conditions. Polyesters are readily hydrolysed by hot aqueous alkalis, such as aq sodium hydroxide. Each ester linkage is hydrolysed to: - the sodium salt of a carboxylic acid, -COO-Na+ and a hydroxyl group -OH.
      • Polyesters can also be hydrolysed with hot aq acid, such as aq hydrochloric acid, although the reaction is much slower than with an aq alkali. The monomer units of the polyester are produced.
      • Polyamides can be hydrolysed by either hot aq acid, such as aq hydrochloric acid, or hot aq alkali, such as aq sodium hydroxide. In acid conditions, the dicarboxylic acid is produced togethr with an ammonium salt of the diamine. In basic conditions, the sodium salt of the dicarboxylic acid and the diamine are formed.
      • Degradable polymers- polylactic acid, made from lactic acid derived from corn starch and polyglycolic acid, made from glycolic acid isolated from sugar cane and unripe grapes.
      • Photogradable polymers- Synthetic polymers designed to become weak and brittle when exposed to sunlight for prolonged periods. They can be manufactured by blending the polymer with light-sensitive additives that catalyse the breakdown of the polymer in the presence of UV radiation or by incorporating carbonyl bonds within the backbond of the polymer. These bonds absorb light energy and break, fracturing the polymer chain.
    • Optical Isomerism
      • Arises in organic molecules that contain a carbon atom attached to four different atoms or groups of atoms. If it has a chiral carbon, then two mirror-image arrangements are possible in space.
      • The mirror-image arrangements are non-superimposable mirror images of each other. These are called optical isomers or enantiomers. These are chemically identical but rotate plane-polarised light in different directions.
      • For two chiral carbons, only two pairs of optical isomers are formed.
      • One of the optical isomers rotates the light clockwise and the other anti-clockwise. A mixture containing equal amounts of each isomer is known as a racemic mixture. This has no effect on plane-polarised light because the rotations cancel each other.
      • There are naturally occuring a-amino acids, such as sugars. Optical activity is important in biological systems where only one of the isomers is biolocally active. In plants and animals, only one of the optical isomers is synthesised naturally and only one will interact with an enzyme due to the stereospecific nature of enzymes.
  • Definitions
    • Polymers and synthesis
      • Amino Acids
        • Amino acids are the building blocks of two groups of biological molecules- peptides and proteins. Amino acids are soluble in both acids and bases.
        • Proteins act as enzymes, hormones and antibodies. Polypeptides transport substances such as oxygen, vitamins and minerals to cells throughout the body. Structural proteins, such as collagen and keratin are responsible for the formation of bones, teeth and the outer layer of skin, and they help to maintain the structure of blood vessels and other tissues.
        • The general formula of an a-amino acid is RCH(NH2)COOH. The R group can be an -OH, -SH, -COOH or -NH2 group.
        • A pH that is more acidic than the isoelectric point means that the amino acid accepts a proton and acts as a base, forming a positively charged ion. A pH which is more alkaline than the isoelectric point means that the amino acid donates a proton to the base and acts as an acid, forming a negatively charged ion.
      • Polypeptides and proteins
        • A protein or polypeptide is a long chain of amino acids joined together by peptide linkages. This is made by condensation reactions of amino acids.
        • When drawing a polypeptide, one end of the structure contains a C=O group and the other end an N-H group. Polypeptides are drawn with their ends open.
        • For each amino acid added to the chain, a molecule of water is formed. A polypeptide contains many linked amino acids. Proteins are long polypeptides.
        • Acid hydrolysis- Polypeptides and proteins are hydrolysed using aqueous acid. During this, the amino acids formed are positively charged because of the presence of H+ ions from the acid.
        • Alkaline hydrolysis- A form of aqueous sodium hydroxide is used at just above 100.C. The polypeptide or protein is broken down into amino acids in the form of their sodium salts.
      • Condensation Polymerisation- polyamides
        • In a polyamide, the monomers have a carboxyl group, -COOH, and an amine group, NH2. 1) Polyamide made by reacting a dicarboxylic acid monomer with two -COOH groups and a diamine with two -NH2 groups.
        • 2) Polyamides made by reacting one type of monomer unit containing both -COOH and -NH2 groups. Amino acids are this type of monomer. Amide linkage forms and water is eliminated
        • Kevlar is an example and it has fire resistance and has a higher strength than steel. It is used to make protective clothing.
      • Addition and condensation- polymerisation
        • Addition polymers are made from one type of monomer only and there is no product other than the polymer. Each one has their own specific properties.
        • Condensation polymers are made up of two monomers which join together to eliminate a small molecule such as water or HCl. These monomers have two functional groups in their structure.
        • How to identify the type of polymerisation- If the monomer contains a double bond, then the polymerisation is addition; if the backbone of the polymer is a continuous chain of carbon atoms, then the polymer is likely to have been made by addition and the monomer will be an alkene.
        • If there are two monomers each with two normal or different functional groups, then the polymerisation is condensation; if the polymer contains ester or amide linkages, then the polymerisation is condensation.
      • Organic synthesis of aromatic compounds
        • An ester can be made from an alcohol and a carboxylic acid; aldehydes can be oxidised to carboxylic acids and reduced to primary alcohols; and amines can be made from halogenoalkanes using excess ammonia.
      • Condensation Polymerisation- polyesters
        • Polyesters from two types of monomer units- A bond forms between a hydroxyl group on the diol and a carbonyl group on a dicarboxylic acid. An ester linkage is formed and water is eliminateed.
        • Polyesters are used in making carpets, sports clothing and shirts. In clothing and bedding, the polyesters are blended with cotton. Almost all polyesters can be machine-washed and machine-dried. It is a strong fibre which is resistant to stretching, shrinking and chemical attack. Unfortunately it burns easily and so it should not be exposed to naked flames.
        • Polyesters from one type of monomer unit- Polyesters can be formed from hydroxycarboxlic acids, which contain both -COOH and -OH groups. During condensation polymerisation, a bond forms between the hydroxyl group on one lactic acid molecule and a carboxyl group on a different lactic acid molecule. This forms an ester linkage and water is eliminated.
      • Organic synthesis of aliphatic compounds
        • How to approach organic synthesis: - A good knowledge of all chemical reactions, reagents and conditions in the specification. The starting material and the product should be checked to spot what has changed. The answer should be then checked and the equations should be balanced.
      • Chirality in pharmaceutical synthesis
        • Synthesising pharmaceuticals- Drugs and medicines act by interacting with materials such as proteins, nucleic acids and with biological systems such as cell membranes. These biological molecules have a complex 3D structure which binds to a drug molecule in only one possible way. The 3D structure determines the pharmacological activity of a drug and whether a phermaceutical will have the desired theraputic effect or not.
        • The production of a single isomer with the correct pharmacological activity presents significant advantages to pharmaceutical companies. This includes; risks from undesirable side effects are reduced and drug doses are reduced.
        • When a chiral compound is synthesised in the laboratory, a mix of optical isomers are formed, but when the same material is made naturally in a living system. it is produced as a single optical isomer.
        • To prepare a chiral compound in the lab, separation techniques are needed to isolate the pharmocologically active isomer. This is diffcult as the optical isomers usually have the same or very similar physical properties incl. melting points, boiling points and solubilities. These techniques include the use of enzymes, electrophoresis and chromatography. These are costly and take a lot of time.
        • Methods used to prepare single chiral isomers- using enzymes as biological catalysts, chiral pool synthesis and use of transition element complexes. Chiral drugs are also used at home as ibuprofen is an anti-inflammatory drug that targets both bone and muscle pain. It blocks messages to the brain and reducing swelling or inflammation. This is commonly used to relieve headaches, back pain and period pain, and to treat cold and flu symptoms and arthritis.
      • Breaking down condensation- polymers
        • Esters can be hydrolysed under acidic or basic conditions. Polyesters are readily hydrolysed by hot aqueous alkalis, such as aq sodium hydroxide. Each ester linkage is hydrolysed to: - the sodium salt of a carboxylic acid, -COO-Na+ and a hydroxyl group -OH.
        • Polyesters can also be hydrolysed with hot aq acid, such as aq hydrochloric acid, although the reaction is much slower than with an aq alkali. The monomer units of the polyester are produced.
        • Polyamides can be hydrolysed by either hot aq acid, such as aq hydrochloric acid, or hot aq alkali, such as aq sodium hydroxide. In acid conditions, the dicarboxylic acid is produced togethr with an ammonium salt of the diamine. In basic conditions, the sodium salt of the dicarboxylic acid and the diamine are formed.
        • Degradable polymers- polylactic acid, made from lactic acid derived from corn starch and polyglycolic acid, made from glycolic acid isolated from sugar cane and unripe grapes.
        • Photogradable polymers- Synthetic polymers designed to become weak and brittle when exposed to sunlight for prolonged periods. They can be manufactured by blending the polymer with light-sensitive additives that catalyse the breakdown of the polymer in the presence of UV radiation or by incorporating carbonyl bonds within the backbond of the polymer. These bonds absorb light energy and break, fracturing the polymer chain.
      • Optical Isomerism
        • Arises in organic molecules that contain a carbon atom attached to four different atoms or groups of atoms. If it has a chiral carbon, then two mirror-image arrangements are possible in space.
        • The mirror-image arrangements are non-superimposable mirror images of each other. These are called optical isomers or enantiomers. These are chemically identical but rotate plane-polarised light in different directions.
        • For two chiral carbons, only two pairs of optical isomers are formed.
        • One of the optical isomers rotates the light clockwise and the other anti-clockwise. A mixture containing equal amounts of each isomer is known as a racemic mixture. This has no effect on plane-polarised light because the rotations cancel each other.
        • There are naturally occuring a-amino acids, such as sugars. Optical activity is important in biological systems where only one of the isomers is biolocally active. In plants and animals, only one of the optical isomers is synthesised naturally and only one will interact with an enzyme due to the stereospecific nature of enzymes.
    • Peptide
      • A compound made of amino acids and linked by peptide bonds.
    • Zwitterion
      • A dipolar ionic form of an amino acid that is formed by the donation of  hydrogen ion from the carbonyl group to the amino group. Because both charges are present, there is no overall charge.
    • Isoelectric point
      • The pH value at which the amino acid exists as a zwitterion.
    • Condensation reaction
      • One in which two small molecules react together to form a larger molecule with the elimination of a small molecule such as water.
    • Stereoisomers
      • Are species with the same structural formula but with a different arrangement of atoms in space.
    • Chiral carbon
      • Is a carbon atom attached to four different atoms or groups of atoms.
    • Repeat unit
      • The specific arrangement of atoms that occurs in the structure over and over again. Repeat units are included in brackets, outside which is the letter n.
    • Biodegradable polymer
      • A polymer that breaks down completely into carbon dioxide and water.
    • Degradable polymer
      • A polymer that breaks down into smaller fragments when exposed to light, heat or moisture.
    • Pharmacological activity
      • The beneficial or adverse effects of a drug on living matter.

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goodstudent1

So interesting

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