Amines, Amino acids and Polymers

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A Levels Chemistry (Unit 4) Flashcards on Amines, Amino acids and Polymers, created by megan.radcliffe16 on 01/12/2014.
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Flashcards by megan.radcliffe16, updated more than 1 year ago
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Question Answer
How can Amines be classified? Primary Secondary Teritary
What is the simplest amine? Ammonia
What is a Quaternary ammonium salt? A quaternary ammonium salt is an ammonium salt, in which all the hydrogens have been replaced by an alkyl group
Why are amines bronsted Lowry bases? Because the lone pair on the N atom can readily accept a proton
What does the strength of the base depend upon? It depends upon the availability of the N lone pair to form a bond with the H+. The higher the electron density of the lone pair on the N, the better it will accept the H+. = stronger the base.
Why are carbon chain ( aliphatic) amines stronger bases than ammonia? Alkyl groups are electron releasing so they push the electron density towards the nitrogen, so therefore increase the availability of the nitrogen lone pair to accept the H+.
What is the order of strength of amines? Tertiary > secondary > primary
why are tertiary and secondary amines stronger than primary? The N lone pair has a greater electron density because of the enhanced inductive effect of more alkyl groups.
Why are aromatic amines weaker than ammonia? The N lone pair interacts with the delocalised π electrons - become partially delocalised into benzene ring. Reduces availability of N lone pair to accept a proton and so reduces strength.
What type of reaction occurs with ammonia and haloalkanes to form a primary amine? Nucleophillic substitution.
why does the primary amine formed in nucleophillic substitution act as a nucleophille? It has a lone pair of electrons on the N atom
Why are primary amines able to react to form secondary amines? Because of the lone pair of electrons on the N atom.
How is further substitution possible? what does this lead to? The secondary amine is able to act as a nucleophile. Leads to the formation of Tertiary and then quaternary ammonium salts.
How can the reaction be altered to have primary amines as the main product? Use a large excess of ammonia
How can the reaction be altered to have the quaternary ammonium salt as the main product? have a large excess of the haloalkane.
What is the use of Quaternary ammonium salts? Fabric softeners
How do you prepare aliphatic amines? 1. Reaction of excess NH3 with Haloalkanes 2. Reduction of nitrile compounds
what takes place in the reduction of nitrile compounds. 1. nitrile is produced by nucleophilic substitution. 2. Reduce the nitrile compound
what are the two options for the reduction of nitrile compounds? 1. Reduction using LiAIH4 in dry ethoxyethane 2. Catalytic hydrogenation using H2 and Ni catalyst
What is the process of preparing primary aromatic amines? 1. Reduction using Sn and conc. HCl, followed by NaOH 2. Catalytic hydrogenation using H2 and Ni catalyst
What is the structure of an amino acid?
what is the simplest amino acid? Glycine (aminoethanoic acid)
why are all amino acids optically active? What does this mean? They all have a Chiral centre. It means that it is able to rotate the plane of polarised light.
What property does an amino acid show? Amphoteric
As amino acids are amphoteric, what are they able to do? Amino acids have a carboxylic acid and an amine group. As acids- able to donate proton to bases. As Bases- able to accept protons.
What are the characteristics of pure state amino acids? 1. White crystalline solid 2. Dissolve in water easily 3. High melting point
What is a Zwitterion?
Why does the high melting point occur? There are ionic bonds present between the zwitterions.
what happens as the pH increases to the zwitterion? The NH3 group loses a proton and acts as an acid.
what happens to the zwitterion as the pH decreases? The COO- group gains a proton and acts as a base
what do Zwitterions behave as? Buffers
What is the link between amino acids? Peptide link
why type of reaction occurs between two amino acids? Condensation reaction
what do: 1. two amino acids 2. three amino acids 3. Many amino acids form? 1. dipeptide 2. tripeptide 3. Polypeptide
What is the primary structure of an amino acid? The particular order of the amino acid.
How is an amino acid chain in a protein held into shape? By hydrogen bonding
What are the two basic shapes the the proteins due to hydrogen bonding? What are those kind of structures? 1. α helix 2. β pleated sheet secondary protein structures
what is the type of reaction where proteins are broken down to form amino acids? Hydrolysis
How can a mixture amino acids be separated and identified? by using Paper chromatography or thin layer chromatography
How can the peptide link by hydrolysed? Boil the protein with 6 mol dm-3 for 24 hours
What are polymers? Large molecules built up from many monomers.
what kind of mechanism takes place during addition polymerisation? Free radical mechanism
What are the conditions of addition polymerisation? High pressure presence of an initiator which provides free radicals.
how are esters formed? A reaction between carboxylic acid and an alcohol
how are polyesters formed? When a dicarboxylic acid reacts with diols
what is an example of a polyester and how is it formed? Terylene formed from benzene-1,4- dicarboxylic acid and ethane-1,2-diol
How are Amides formed? the reaction of a carboxylic acid and an amine
How are Polyamides formed? Dicarboxylic acids react with diamines
what are an examples of a polyamide? Howare they manufactured? Nylon-6,6 Reaction between 1,6-diaminohexane and hexane-1,6-dioic acid Kevlar benzene-1,4-diamine and benzene-1,4-dicarboxylic acid
why are addition polymers non biodegradable? They are saturated and chemically unreactive. They have strong, non polar C-C and C-H bonds.
How are polyesters and polyamides hydrolysed? By being in the presence of strong acid or a specific enzyme
What bond is broken in polyesters during hydrolysis? Polar ester linkage
What bond is broken during the hydrolysis of polyamides? Polar amide linkage
What is produced during the inceneration of polymers? Greenhouse gases (CO2, methane) nitrogen dioxide cyanide
What are the advantages of recycling? Conserves supplies Saves energy
what are the disadvantages of recycling? Plastics need to be collected, transported and sorted uses energy uses man power Expensive
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