Organic Chemistry: Amines and Amino Acids Quiz
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Questions and Answers

What is needed for the catalytic hydrogenation of nitriles?

  • Hydrogen and nickel catalyst (correct)
  • Nitrogen and tin catalyst
  • Oxygen and nickel catalyst
  • Hydrogen and platinum catalyst

Aromatic amines are produced from the reduction of nitrobenzene using a zinc catalyst.

False (B)

What is the general formula for an α-amino acid?

RCH(NH₂)COOH

The state in which the amine group has a positive charge and the carboxyl group has a negative charge is called a __________.

<p>zwitterion</p> Signup and view all the answers

Match the descriptions with the correct terms:

<p>α-amino acids = Contain both a carboxylic acid and an amine group Zwitterions = Charged form of amino acids at isoelectric point Amides = Formed from reactions with acyl chlorides Hydrochloric acid = Used in the reduction of nitrobenzene</p> Signup and view all the answers

What describes the behavior of amino acids in relation to acids and bases?

<p>They can behave as both acids and bases. (D)</p> Signup and view all the answers

Primary amides have the structure RCONH₂.

<p>True (A)</p> Signup and view all the answers

What is the significance of the isoelectric point in amino acids?

<p>It is the pH at which the overall charge of the molecule is zero.</p> Signup and view all the answers

What are the classifications of amines based on the number of alkyl groups bonded to the nitrogen atom?

<p>Primary, secondary, tertiary (B)</p> Signup and view all the answers

Amines can only produce primary amines through nucleophilic substitution reactions.

<p>False (B)</p> Signup and view all the answers

What do amines release into solution when they react with water?

<p>OH- ions</p> Signup and view all the answers

The reaction between amines and acids forms __________.

<p>ammonium salts</p> Signup and view all the answers

What is the role of ammonia in the reaction with halogenoalkanes?

<p>Acts as a nucleophile (D)</p> Signup and view all the answers

To ensure that only a single substitution occurs when forming amines, ammonia should be added in excess.

<p>True (A)</p> Signup and view all the answers

What type of amine is formed from one mole of halogenoalkane and two moles of ammonia?

<p>Primary amine</p> Signup and view all the answers

Match the following amine reactions with their products:

<p>Amines + Water = Releases OH- ions Amines + Acids = Forms ammonium salts Halogenoalkanes + Ammonia = Produces primary amines Excess Ammonia = Minimizes product mixture</p> Signup and view all the answers

What is the primary purpose of using a vacuum in filtration under reduced pressure?

<p>To increase the rate of filtration (B)</p> Signup and view all the answers

A Buchner funnel is used in gravity filtration

<p>False (B)</p> Signup and view all the answers

Why is it important to use a minimum volume of hot solvent during recrystallisation?

<p>To maximise the solubility of the solute while minimising the amount of solvent used.</p> Signup and view all the answers

During recrystallisation, the solution is filtered through hot apparatus using _____ filtration to remove insoluble impurities.

<p>gravity</p> Signup and view all the answers

What happens when a sample with low purity is tested during melting point analysis?

<p>The melting point will occur over a range of temperatures. (A)</p> Signup and view all the answers

The solubility of a solute decreases with temperature.

<p>False (B)</p> Signup and view all the answers

What is the purpose of wetting the filter paper with the solvent before filtration?

<p>Wetting the filter paper helps it to adhere to the Buchner funnel and prevents the solid from getting caught beneath the paper.</p> Signup and view all the answers

Match each technique to its primary use

<p>Vacuum Filtration = Separation of solid product from solvent using a vacuum Gravity Filtration = Removal of insoluble impurities from a solution Recrystallisation = Purification of a solid based on solubility Melting Point Analysis = Testing the purity of a solid material</p> Signup and view all the answers

What is the primary purpose of extending carbon chain length in organic synthesis?

<p>To create new molecular structures (C)</p> Signup and view all the answers

Hydrogenation is the process of reducing nitriles into alcohols.

<p>False (B)</p> Signup and view all the answers

What ion acts as the nucleophile in nucleophilic substitution reactions involving nitriles?

<p>CN⁻</p> Signup and view all the answers

Nitriles can be converted into __________ acids through acid hydrolysis.

<p>carboxylic</p> Signup and view all the answers

Match the following reactions with their corresponding descriptions:

<p>Hydrogenation = A process that reduces nitriles to amines Friedel-Crafts Alkylation = Introduces a carbon chain into an aromatic compound Nucleophilic Addition = Involves the attack of a nucleophile on a carbonyl carbon Acid Hydrolysis = Converts nitriles into carboxylic acids</p> Signup and view all the answers

Which catalyst is commonly used in catalytic hydrogenation?

<p>Nickel (A)</p> Signup and view all the answers

Friedel-Crafts acylation substitutes a hydrogen atom on the benzene ring for an alkyl group.

<p>False (B)</p> Signup and view all the answers

What reaction occurs when a nitrile is heated with dilute aqueous acid?

<p>Acid hydrolysis</p> Signup and view all the answers

What does Friedel-Crafts alkylation primarily substitute on the benzene ring?

<p>An alkyl group (C)</p> Signup and view all the answers

During Friedel-Crafts alkylation, H+ ions are produced as a side product.

<p>True (A)</p> Signup and view all the answers

What is the role of aluminium chloride in Friedel-Crafts alkylation?

<p>It acts as a catalyst.</p> Signup and view all the answers

The technique that continually heats the contents of a flask to complete reactions is called _____ .

<p>reflux</p> Signup and view all the answers

Match the following techniques with their descriptions:

<p>Reflux = Continual heating in a reaction Distillation = Separating liquids based on boiling points Recrystallization = Purifying solid compounds Solvent extraction = Isolating compounds using a solvent</p> Signup and view all the answers

What is produced when the reactive intermediate formed in Friedel-Crafts alkylation is attacked by the benzene ring?

<p>An alkyl benzene (C)</p> Signup and view all the answers

Distillation can be used to purify solids effectively.

<p>False (B)</p> Signup and view all the answers

What happens to vapors during the distillation process?

<p>They evaporate and then condense back into a liquid.</p> Signup and view all the answers

What is the purpose of synthesis pathways in organic chemistry?

<p>To convert starting materials into a target product (C)</p> Signup and view all the answers

Synthesis maps only show single-step reactions.

<p>False (B)</p> Signup and view all the answers

What is the melting point?

<p>The temperature at which a substance changes from solid to liquid.</p> Signup and view all the answers

The formation of __________ is a consideration when designing a synthetic pathway.

<p>isomers</p> Signup and view all the answers

Match the following types of synthesis with their descriptions:

<p>Single-step = Direct transformation from reactants to product Multi-stage = Involves one or more intermediate compounds Synthesis maps = Summarizes multistep reactions Batch process = Occurs in discrete quantities rather than continuously</p> Signup and view all the answers

Which factor is NOT typically considered when designing a synthetic pathway?

<p>Color of the product (A)</p> Signup and view all the answers

The term 'enantiomer' refers to molecules that are identical in structure but differ in spatial arrangement.

<p>True (A)</p> Signup and view all the answers

What is an example of a synthetic route?

<p>Converting chloroethane to ethanoic acid.</p> Signup and view all the answers

Flashcards

Amines

Organic compounds derived from ammonia (NH3) where one or more hydrogen atoms have been substituted by alkyl groups.

Classifying Amines

Amines are classified as primary, secondary or tertiary based on the number of alkyl groups attached to the nitrogen atom.

Amines as Bases

Amines act as bases, accepting a proton (H+) from water to form an alkaline solution.

Ammonium Salt Formation

Amines react with acids to form ammonium salts. This reaction is due to the amine's ability to act as a base and accept a proton from the acid.

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Nucleophilic Substitution of Amines

A reaction where a halogenoalkane reacts with ammonia to form an amine and an ammonium salt. The reaction can continue to produce a mixture of amines and ammonium salts.

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Primary Amine Formation

The desired primary amine can be obtained by using excess ammonia, thus pushing the reaction towards primary amine formation.

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Mixture of Products

Heating halogenoalkanes with ammonia in a sealed tube under high pressure leads to a mixture of products due to multiple substitutions of hydrogen atoms in ammonia with alkyl groups.

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Quaternary Ammonium Salt

The production of a quaternary ammonium salt occurs when all hydrogen atoms in ammonia have been replaced by alkyl groups, resulting in a positively charged nitrogen with four alkyl groups attached.

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Friedel-Crafts Alkylation

A chemical process that substitutes an alkyl group for a hydrogen atom on a benzene ring.

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Catalyst

A substance that speeds up a chemical reaction without being consumed in the process.

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Electrophile

A molecule that is capable of accepting a pair of electrons.

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Reflux

A technique used to heat a reaction mixture while preventing the loss of volatile compounds.

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Distillation

A technique used to separate liquids with different boiling points.

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Recrystallization

The process of removing impurities from a solid substance by dissolving it in a hot solvent and then allowing it to cool slowly.

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Solvent extraction

A technique used to separate components of a mixture by their solubility in different solvents.

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Melting point determination

A method used to determine the temperature at which a solid melts.

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Nucleophilic Addition to Carbonyl

A reaction where a nucleophile attacks a molecule with a carbonyl group. This is typically used in the synthesis of nitriles.

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Nitrile

A compound containing a cyano group (-C≡N). They are used in organic synthesis to extend carbon chains and form other functional groups.

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Hydrogenation of Nitriles

The process of adding hydrogen atoms to a molecule, often using a catalyst like nickel. Used to convert nitriles to amines.

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Extending the Carbon Chain

The carbon chain in an organic molecule can be extended by forming a new C-C bond. This is often achieved using reactions like nucleophilic addition or Friedel-Crafts reactions.

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Acyl cation

A reactive intermediate formed during Friedel-Crafts Acylation, where the acyl group is attached to the catalyst. It acts as an electrophile in the substitution reaction.

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Nucleophilic Attack in Friedel-Crafts

The benzene ring acts as a nucleophile and attacks the electrophilic acyl cation formed in Friedel-Crafts Acylation, leading to the formation of a new C-C bond.

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Reduction of Nitriles

A chemical reaction where a nitrile is converted into an amine using hydrogen gas and a nickel catalyst.

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Preparation of Aromatic Amines

Aromatic amines are produced by reducing a nitrobenzene molecule using concentrated hydrochloric acid and a tin catalyst.

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What defines an α-amino acid?

Amino acids carry both carboxyl and amine functional groups connected to the same carbon atom.

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Amino Acid Reactivity

Amino acids can act as both acids and bases depending on the reaction conditions.

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Zwitterion - What is it?

A zwitterion is an amino acid where the amine group is positively charged and the carboxyl group is negatively charged. It occurs when the molecule is at its isoelectric point.

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Amides Synthesis

Amides are formed through a nucleophilic addition-elimination reaction between amines and acyl chlorides.

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Primary Amides Structure

Primary amides have the structure RCONH2, where R is an alkyl group.

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Amines as Nucleophiles

Amines can act as nucleophiles, attacking acyl chlorides to form amides and further substituted amides.

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What is the melting point?

The temperature at which a solid changes to a liquid.

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What is a synthetic route?

A series of chemical reactions used to transform starting materials into a desired product.

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What is product yield?

The amount of product formed in a chemical reaction, often expressed as a percentage.

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What is Le Chatelier's principle?

A chemical reaction that can be controlled by changing factors like temperature, pressure, and concentration.

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What is reaction setup?

The arrangement of a chemical reaction, including things like catalysts, reagents, and conditions.

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What is a batch process?

A method of production where reactants are added to a container at a specific time, and products are removed later.

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What is a continuous process?

A method of production where reactants are constantly fed into a system, and products are continuously removed.

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What are isomers?

Molecules that have the same chemical formula but different arrangements of atoms in space.

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Vacuum filtration

A technique using a vacuum to accelerate filtration by decreasing pressure in the flask, pulling solvent through the filter paper.

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Buchner funnel

A specialized funnel with a flat, perforated base, used alongside a side-arm flask for vacuum filtration.

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Side-arm flask

A specialized flask with a side arm for connecting a vacuum source, used in conjunction with a Buchner funnel.

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Melting point analysis

A common method to determine the purity of a solid by measuring the temperature range at which it melts. A purer substance will have a narrower melting point range.

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Capillary tube

A small glass tube, open at one end, used to hold small samples for melting point determination.

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Melting point apparatus

Heating apparatus specifically designed to measure the melting point of a substance by controlling the temperature and observing the phase change.

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Melting point

The point at which a solid transitions to a liquid state.

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Study Notes

Amines

  • Amines are produced when one or more hydrogen atoms in ammonia are replaced by alkyl groups.
  • They are classified as primary, secondary, or tertiary depending on the number of alkyl groups bonded to the nitrogen atom.
  • Amines are basic and react with water to form an alkaline solution.
  • The lone pair of electrons on the nitrogen atom accepts a hydrogen ion from water, acting as a base.
  • This releases hydroxide ions (OH⁻) into the solution.
  • Amines react with acids to form ammonium salts.
  • Again, the amine acts as a base, accepting a proton (H⁺) to form a quaternary ammonium salt.
  • Aliphatic amines can be made via a nucleophilic substitution reaction between a haloalkane and ammonia in a sealed tube.
  • This reaction produces a primary amine and an ammonium salt.
  • The substitution reaction can continue until all hydrogens are replaced.
  • A mixture of products are formed

Reduction of Nitriles

  • Aliphatic amines can be produced by the reduction of nitriles by hydrogenation with a nickel catalyst.

Preparation of Aromatic Amines

  • Aromatic amines can be prepared by reducing nitrobenzene using concentrated hydrochloric acid and a tin catalyst.

Amino Acids, Amides and Chirality

  • α-amino acids have a carboxylic acid group and an amine group bonded to the same carbon atom
  • Different amino acids have different side chains ('R' group).
  • The general formula for an α-amino acid is RCH(NH2)COOH.
  • Amines can react with acyl chlorides to form amides via nucleophilic addition-elimination.
  • Amides have the structure C=O and NHR (where R is an alkyl group or hydrogen atom).
  • Primary amides have the structure RCONH2.
  • secondary amides(N-substituted amide) have addition carbon chain bonded to the nitrogen atom.

Chirality

  • A chiral center is a carbon atom bonded to four different groups.
  • The molecule has no plane of symmetry.
  • The chiral center is commonly indicated by an asterisk (*) next to the asymmetric carbon.

Optical Isomers

  • Optical isomers are stereoisomers with the same molecular formula but a different spatial arrangement.
  • The presence of a chiral center leads to two possible isomers that are non-superimposable mirror images (enantiomers).
  • Enantiomers rotate plane-polarized light in opposite directions.
  • All amino acids (except glycine) are chiral and optically active.

Polyesters

  • Polyesters are formed by the reaction of a dicarboxylic acid with a diol.
  • The reaction produces an ester linkage (-COO-).
  • Terylene (PET) is a common polyester made from ethane-1,2-diol and benzene-1,4-dicarboxylic acid.
  • Polyesters are useful because they are biodegradable.

Polyamides

  • Polyamides are condensation polymers formed by the reaction between a dicarboxylic acid and a diamine.
  • The reaction produces an amide linkage (-CONH-).
  • Examples include nylon 6,6 (from 1,6-diaminohexane and hexanedioic acid) and Kevlar (from benzene-1,4-dicarboxylic acid and 1,4-diaminobenzene).

Hydrolysis

  • Ester and amide linkages in polyesters and polyamides can be broken down by acid or base hydrolysis in the presence of water.
  • Acidic conditions result in the formation of alcohols and carboxylic acids or diols and dicarboxylic acids respectively.
  • Basic conditions result in the formation of carboxylate salts and alcohols.

Carbon-Carbon Bond Formation

  • Carbon chains can be extended by C-C bond formation.
  • Nitriles are useful for this, as they can be converted to other functional groups.
  • Nucleophilic substitution reactions can form nitriles, typically with haloalkanes and cyanide ion (CN⁻) in ethanol (for SN1).

Friedel-Crafts Reactions

  • Friedel-Crafts acylation substitutes an acyl group for a hydrogen atom on the benzene ring via the reaction between acyl chloride and aluminium chloride.
  • Friedel-Crafts alkylation substitutes an alkyl group for a hydrogen atom via the reaction between a haloalkane and aluminium chloride.

Organic Synthesis

  • Different techniques are used in Organic Synthesis.
  • Methods for preparation and purification include: reflux, distillation, melting point determination, boiling point determination, washing and drying, recrystallization, and solvent extraction.

Multistage Synthesis

  • This involves more than one step to prepare an organic product from starting materials.

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Description

Test your knowledge on amines and amino acids with this quiz. Explore key concepts including catalytic hydrogenation, isoelectric points, and the classifications of amines. Ideal for students studying organic chemistry and biochemistry.

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