5.LAB 40 – Chemistry – Flashcards
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JOB:
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Oxidize 2-Ethyl-1,3-hexanediol with NaOCl (bleach) Perform an IR spectrum test to determine which of the 3 possible products will be formed, due to the oxidation.
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RESULT:
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The IR spectrum indicated that the product was identical to structure 1. The major distinction was the presence of a C-H bond attached to the carbonyl group which portrayed a signal at 1700 cm-1.
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1. Draw the possible product of the following reaction
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a. SEE LAB
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2. Why is acetic acid added to the reaction mixture?
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a. Acetic acid converts NaOCl to HOCl, the actual oxidant
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4. How might your product's IR spectrum differ from the starting material's IR spectrum?
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a. The IR spectrum of the starting material will present signals for OH but lack a signal for the carbonyl group, that will be present in the IR spectrum of the product. The hydroxyl of starting material is oxidized to a carbonyl group in the product.
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5. The starch iodide test of the reaction mixture came out negative during the one hour period. What should you do?
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a. If the starch iodide tests negative, you then add more bleach, because the starch iodide test looks for the presence of NaOCl, so when the test is negative, you add more.
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3. Write a balanced equation for the reaction between bleach and start iodide
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a. NaOCl + NaHSO3 → NaCl + NaHSO4 [NaOCl is bleach]
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1) Purpose of Acetic Acid? and draw 3 products
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to convert NaOCl to HOCl, the actual oxidant
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2) Draw addition under reflux
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-separatory funnel -west condenser -claisen adapter -boiling flask
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3) Why do we leave an opening at the top of separatory funnel during addition of NaOCl to flask?
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so NaOCl can keep dripping and prevent vacuum formation
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4) Draw product with CrO3
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not bleach
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JOB
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Oxidize 2-Ethyl-1,3-hexanediol with NaOCl (aq) bleach and record the IR spectrum to determine which of the 3 products formed
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NaOCl
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Sodium Hypochlorite (Bleach)
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Chlorine bleach NaOCl
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Clorox or Javex - Most are 5.15% NaOCl New Ultra Chlorox is 6% NaOCl (less needed of it)
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Use more bleach than directions say
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Decreases with age
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Acetic Acid
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converts NaOCl to HOCl - the actual oxidant, hypochlorous acid
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Starch Iodide Paper
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tests for presence of hypochlorite, turns blue-black if too much NaOCl If test is negative - add more bleach
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Rxn mixture is heterogeneous
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has separate organic and aqueous layers
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Stir vigorously
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to keep well mixed the separated layers
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inadequate mixing leads to
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low yield
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Add NaHSO3 sodium bisulfite at end of rxn
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to any unreacted NaOCl to convert to NaCl, table salt NaOCl + NaHSO3 --> NaCl + NaHSO4
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Diethyl Ether
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used to extract product from mixture, evaporate ether, and purify the product by simple distillation
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GREEN Synthesis
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1) respectable atom economy 2) use of acetic acid catalyst 3) use of hypochlorite bleach as oxidant (not harmful chromic acid) 4) Harmless by products
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Hygroscopic
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absorbs water vapor from the atmosphere, used as a drying agent to prevent condensation in natural gas pipelines
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Sodium hypochlorite
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to disinfect drinking water
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Acetic acid harm
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naturally occurring, breaks down to carbon dioxide and water
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Sodium hydroxide NaOH
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may be harmful with aqueous organisms - neutralizes excess acetic acid and itself is neutralized
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2-Ethyl-1,3-hexanediol
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6-12 insect repellent
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want to convert
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hydroxyl to carbonyl in oxidation with NaOCl
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simplest diol
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antifreeze, plastics
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Diol
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alcohol 2 OH's
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Methanol
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antifreeze, toxic
