chemsample-lab2-introduction

The Diels-Alder Reaction, in the chemists world, is generally considered to be the "Mona Lisa" of chemical reactions. Awarded the Nobel Prize in 1928, Otto Paul Hermann Diels & Kurt Alder were able to devise a reaction that required very little energy input to form cyclohexene rings - a task previously unheard of! As a result of this discovery, the field of chemistry has expanded considerably ~ We (the students of Organic Chemistry II) are now going to apply the discovery of Diels & Alder, essentially recreating their discoveries from nearly 90 years ago! (//Be sure to check out the link above for an interesting rendition of the basic reaction mechanism!//) The general reaction mechanism occurs through the "cycloaddition of a conjugated diene, and a molecule containing a carbon-carbon double, or triple bond." This reaction occurs via a single concerted step, forming the cyclohexene ring. The basic mechanism occurs as follows:
 * __[|Diels-Alder!] __**

//Diene + Dienophile = Cyclohexene Ring//



Essentially what is occurring is the formation of a single new product from two lesser individual molecules - under high heat (110 deg/c), and in the presence of water. The specific reagents used in the following experiments (there are actually //two// protocols - involving different reagents, and filtering techniques) are as follows:

Reaction Type One!
 * Diels-Alder Reaction of**

[|2,3-dimethyl-1,3-butadiene]

&

[|Maleimide]

Reaction Type Two!
 * Diels-Alder Reaction of**

[|2,3-dimethyl-1,3-butadiene]

&

[|Dimethyl Fumarate]

As in our previous lab, each pair of students will be conducting a unique lab protocol - with unique quantities of reactent chemicals and/or unique procedures for the process itself. These are listed out under the materials & methods section - However, here is a breakdown of what will be occurring ~ Two pairs of students will conduct a procedure involving the reaction of 2,3-dimethyl-1,3-butadiene & Maleimide (in presence of water & heat!), one pair using regular quantities listed in the lab manual ... and another using double the regular quantities. A third pair of students will conduct the procedure involving the reaction of 2,3-dimethyl-1,3-butadiene & Dimethyl Fumarate (in presence of water & heat). Product yields will be obtained after proper drying of the product is done (via vacuum and/or rotary evaporation - dependent on the method used) ... and a melting point range will be determined via a MP apparatus (this melting point should give you an indication of the compounds chemical structure, & purity). The final step in the lab is to run Infrared analysis on the obtained sample. This, if time permits, will also be done. If not, the process will wait until a following week, where more time is available (Note - that the importance of IR must be understood! It will give you a clear indication of the samples chemical structure - which is essentially the base idea of the experiment ... other than conducting the experiment for its own sake!). Orgo-and-Out!

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