The Wittig Reaction – Lab Report assignment

The Wittig Reaction – Lab Report assignment Words: 834

Witting discovered the route to alikeness through yield molecules (1). Witting was educated originally at Tubing; Witting spent periods at Brainwashing, Prefigure, back to Tubing again before taking up the post as director of the organic chemistry department at Heidelberg (1 Witting became an emeritus professor in 1967, where he remained until the end of his notable career (1). In 1967, he won the Otto Hahn Prize, and in 1979, he and Herbert C. Brown were jointly awarded the Nobel Prize for their development of the use of boron and phosphorus- intonating compounds for important reagents in organic synthesis (1).

The foundation of the Witting reaction is not complex. Phosphorus is a second row element – in-group 5 – like nitrogen, but unlike nitrogen, has the ability to expand its valence from 3 to 4, 5, or even 6 (1). The stable 5 valences are met in compounds like phosphoric acid and PC (1 Witting discovered that phosphates, which are the phosphorus equivalent of amines, easily form phosphorous salts with alkyl halides and that these salts readily lose HEX with strong base. This product is called an yield or a phosphorous. The yield is a polar molecule with a carbonic carbon.

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Figure 1. How to make a phosphorus yield (1) In relation to stereotypical, such as CICS/trans, or E/Z, is still not fully understood in the reaction (2). Trustworthiness’s tend normally to give the Z- (CICS) isomer. Troubleshooting or the presence of groups that stabilize the yield tends to give E- (Trans) geometry (2). The Witting reaction can tolerate all types of functionality. The trans-isomer is more stable and the preferred product or the only product in certain reactions due in part to the reduction of sterile hindrance ND eliminating orbital overlap. Figure 2.

Mechanism for phosphorus yields denoting CICS/trans-isomers (1) The Witting is basically used to convert a carbonyl group, C=O, into an alikeness, C=C. A phosphorus yield is formed and obtained by the treatment of a phosphorus salt with a strong base. These yields are very stable due to resonance and highly reactive (2). Phosphorus yields are generally not isolable and are treated with carbonyl compounds. Once the yield has been generated, it is added to a carbonyl group to give the intermediate known as obtained and is followed by the elimination of the hosepipe oxide.

This elimination has been calculated to occur after the formation of a four-members ring known as an speakerphone. Based on the latest laboratory evidence, such as x-ray diffraction, the Witting reaction may proceed directly through the speakerphone intermediate (2). Figure 3. How to make alikeness using the Witting reaction (1) This reaction goes so well due in part to the formation of the immensely strong P-O bond. The strong bases used to make the yield can be the sodium hydride (NaH), and sodium amide (Anna ). If we have a more acidic H to abstract a eager base such as Note or even An could be used in the reaction.

Another variant on the Witting reaction that is much easier to control and cheaper to carry out is the Witting-Hornier reaction (1). This reaction uses a phosphate ester instead of a phosphate, manufacturing a more reactive yield. Figure 4. Mechanism for Witting-Hornier reaction (1) In the Witting reaction, an organic phosphorus compound with a formal double bond between phosphorus and carbon is reacted with a carbonyl compound. The oxygen of the carbonyl compound is exchanged for carbon, forming a reduce known as an olefin (2).

The method for making olefins has opened up new possibilities, especially for the synthesis of biologically active substances containing carbon-to-carbon double bonds. For example, vitamins such as vitamin A are synthesized industrially using the Witting reaction. DATA & RESULTS The Witting reaction-synthesis of trans-9-(2-phenylalanine) anthracite yielded . 067 g of crystals and a 47 % yield. Under Witting-Hornier parameters, we could hypothesize achieving a yield in the 65 % range. After 30 minutes of reaction time, the solution was removed and 1. L of water and deceleration were added to the vial. The organic (bottom) layer was extracted and placed in a test tube. Calcium chloride pellets were added to dry the deceleration layers and the solvent was removed under vacuum. After approximately 15, minutes a solid had formed and 3 ml of I-propane were added and heated on a hot plate in the hood. The solution was allowed to cool to room temperature then placed in ice to reform crystals. The crystals were vacuum filtered using the Hirsch funnel apparatus and washed with cold deceleration.

The crystals were removed ND were yellow-gold in color and shinny, somewhat metallic in nature. A melting point was obtained and fell in the range of 126-128 as compared to the literature value of 130-132 (2). The melting point could have been lowered due in part to some residual solvent. DISCUSSION The basis of conducting this Witting reaction was to use benzyltriphenylphosphonium chloride with 50% Noah, Witting reagent (yield) and 9-enthralled to yield the trans-9-(2-phenylalanine) anthracite. This molecule has a melting point of 130-132 C.