Lab Report #1
Title: Synthesis of Divanillin
Abstract: The purpose of this experiment was to synthesize divanillin. This was done via the oxidative dimerization of two equivalents of vanillin, using enzyme horseradish peroxidase as the catalyst.
Procedure: Lab Handout: Nishimura, R.T.; Giammanco, C.H.; Vosburg, D.A. J. Chem Educ. 2010, 87, 526-527.
Melting pt (or bp)
Percent Yield Calculation:
1 mg= .001 g, 100 mg= .1 g vanillin
Moles vanillin = .1g/152.15 g/mol= 6.57x10^-4 moles
Density H2O2= 1.45 g/mL
Mass H2O2= 1.45 g/mL x .75mL = 1.088g
Moles H2O2= 1.088g/34.015 g/mol =.032 moles
Limiting reagent = Vanillin
1 mol Divanillin= 2 moles Vanillin
Moles divanillin= .5 mol vanillin= 6.57x10^-4 mol/ 2 = 3.29x 10^-4 mol Mass Divanillin = molar mass x mol = 3.29x 10^-4 x 302.28 g/mol= 0.99g= 99mg
Discussion of experiment:
1) Why is this reaction “oxidative dimerization”?
a. Dimerization is when two structurally similar molecules bond together to form a single compound. The term oxidative means either that a compound has lost an electron (is “oxidized”) or that a substance has bonded with an oxygen molecule. The dimer bond forms between two carbons that have each lost an electron and have one to share. The dimer bond does not involve an oxygen, so this is called oxidative dimerization because two identical compounds are bonded at oxidized carbons.
2) Draw resonance structures for the phenoxide anion:
3) Why does the dimer bond form between the #5 Carbons?
a. When the hydrogen peroxide reacts with the peroxidase, 2 equivalents of a hydroxyl free radical are formed. Those free radicals take a hydrogen (including its electron) from the vanillin molecules, forming phenoxy free radicals. The most stable location for the resonating electron on this free radical is on the number 5 carbon (ortho to the phenol). The resonating electrons on each vanillin free radical form a covalent bond, forming the dimer. 4) Why is this green Chemistry?
a. Green Chemistry, simply put, avoids the use and creation of toxics and waste that harms the environment. Green chemistry seeks to stop pollution from chemical production and to use fewer natural resources. This experiment is green chemistry because the reactants used and the products are all non-toxic and safe for the environment. In specific, this experiment involves one of the Green Chemistry developments Ryōji Noyori made in 2005: the use of hydrogen peroxide for clean oxidations. The hydrogen peroxide in this experiment does not produce toxic waste like heavy metal oxidants do; it only produces water.
1) Nishimura, R.T.; Giammanco, C.H.; Vosburg, D.A. J. Chem Educ. 2010, 87, 526-527. 2) Noyori, Ryoji; Pursuing practical elegance in chemical synthesis Chemical Communications, 2005, (14), 1807–1811
References: 1) Nishimura, R.T.; Giammanco, C.H.; Vosburg, D.A. J. Chem Educ. 2010, 87, 526-527.
2) Noyori, Ryoji; Pursuing practical elegance in chemical synthesis Chemical Communications, 2005, (14), 1807–1811
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