Tag Archives: ibchem

Reduction Reactions (HL)

Just as you can oxidise alcohols to form compounds with a carbonyl group, you can then reduce carbonyl containing compounds back to alcohols.

Reagents for reduction

  • Lithium aluminium hydride                 LiAlH4
  • Sodium borohydride                             NaBH4

Lithium aluminium hydride

Sodium borohydride

 

Structures of the reducing agents

 

 

Read through your text and annotate your notes find the answers to the questions below.

✍️  What difference is there in the conditions under which the two reagents might be used?
✍️   Which reagent is preferred from the reduction of carboxylic acids and why?

Reduction of Carbonyl Containing Compounds

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✍️  For the following starting materials, draw the structures and name to products formed when treated with lithium aluminium hydride.

  • propanoic acid
  • butanone

Conversion of nitrobenzene to phenylamine

This reduction happens via a two step process as summarised below.

✍️   After reading your text or other sources, elaborate on what is happening in both stages in your notes.  Make sure you can answer these questions.

  • Why is a protonated phenylammonium ion produced in the first step?
  • What technique is used to heat the reaction?
  • What is the role of the tin?
  • What is the purpose of using sodium hydroxide in the second stage?

SL Organic Review – Part 1

Here is the review of this topic for SL.  HL students should also take a look at this before reviewing the HL only material.

Introduction to Organic Chemistry

In this section, you will review the following syllabus points:

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At the end of it, you should be able to:

  1. Define a homologous series – put this definition on your definitions page!
  2. Use your knowledge about intermolecular forces (from the Bonding topic), to predict which compounds will have higher boiling points.
  3. Understand the difference between a molecular, structural and empirical formula.
  4. Describe and recognise structural isomers with the same molecular formula.
  5. Use your knowledge of polar and non-polar compounds and intermolecular forces (both from the Bonding topic) to discuss the volatility and water solubility of organic compounds.

How to review

  1. First of all, make a note of any of the points above you are not sure of.
  2. Review your notes from class.
  3. Have a look at one or all of the videos that specifically address these points.

Test Yourself

Review questions.
Review answers.

Organic Nomenclature

In this section you will learn to name and draw the structural formulas of different organic compounds.  You will review the following syllabus points:

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After reviewing this section, you should be able to:

  1.  name and draw alkanes, alkenes, alcohols, aldehydes, ketones, carboxylic acids and alkyl halides
  2. recognise (but not name) amines (amino groups), benzene rings and esters
  3. identify primary, secondary and tertiary alcohols and alkyl halides.

How to review

  1. Note any of the above functional groups that you can’t recognise and/or name.
  2. Review your notes from class
  3. Make flashcards or use a program like Quizlet that has them already made for you!
  4. Learn them!
  5. Use the videos below to help you if you aren’t sure which compound is which or how to name them.

Test yourself

Questions
Answers

Alkanes

In this section, you will learn about the reactivity and reactions of alkanes.   You will review the following syllabus points.

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After reviewing this section, you should be able to:

  1. Explain why alkanes are relatively unreactive.
  2. Write equations for the complete and incomplete combustion of alkanes.
  3. Write equations for the reaction of alkanes with a halogen.
  4. Write the free radical mechanism for the reaction of methane or ethane with either chlorine or bromine.

How to review

  1. Review your notes from class.
  2. For the free radical mechanism, you will only need to be able to write it for methane or ethane.  Learn them.  It follows a pattern.
  3. Check out these videos if you are completely stuck.

Test yourself

Questions – (mechanism questions will come at the end of this review post).
Answers

Alkenes

In this section you will review addition reactions by alkenes and addition polymerisation.  The syllabus points you will be reviewing are:

Screen Shot 2014-03-02 at 8.16.32 PM

After reviewing this section, you should be able to:

  1. Write equations for addition reactions between alkenes and halogens, hydrogen, water and hydrogen halides.
  2. Describe with equations and observations the test for distinguishing between alkanes and alkenes.
  3. Draw sections of addition polymers given the monomer and vice versa.
  4. Say why alkenes are important.

How to review

  1. Review your notes from class, including notes in your lab book and experiments we’ve done with alkanes and alkenes.
  2. Use the videos to help if you get stuck.

Test yourself

Questions
Answers

Putting Part 1 All Together

If you are still unclear on any of the points above, DO NOT proceed to this section.

Seek help from:

  • a class member
  • another class member
  • any grade 11 chem student whose name begins with K
  • any grade 12 chem student whose name begins with K
  • one of the IB chemistry web pages
  • post your question on our community and see if anyone can help
  • post your question on an ib chemistry forum on one of the ib chem pages
  • post your question on twitter #ibchem
  • Google it!

Once you are satisfied that you get everything, then, and only then, try the following more difficult questions.

Many of the questions are similar, so if you get one wrong, study the answer until you understand it, and then try another similar question the next day.

Questions
Answers