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Pinacol is the common name for a dihydric alcohol having I.U.P.A.C. name
2,3-dimethyl-2,3-butadiol
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∙ 13y ago
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What is the synthesis of pinacol and pinacolone?
This reaction was first described by Wilhelm Rudolph Fitting in 1860. the pinacol rearrangement or pinacolone rearrangement is a method for converting a 1,2-diol to a carbanyly compound in a organic chemistry. This 1,2 rearrangement take place under acidi condition. the name reaction come from the rearrangement of pinacol to pinacolone.
Where does the name pinacol come from?
Comes from greek word 'pinax'
Scope of pinacol rearrangment in organic synthesis?
I don't really understand your question but pinacol (a diol) rearranges itself to form a carbonyl compound under acidic conditions. One of the OH groups becomes protonated and leaves as H2O forming a tertiary carbocation. A methyl group migrates over to the carbocation leaving a positive charge on the carbon with the remaining OH group. One of the lone pairs on the oxygen forms a double bond with the carbon. The proton on the oxygen then leaves to form a carbonyl compound called pinacolone. Check this out for more info. http://en.wikipedia.org/wiki/Pinacol_rearrangement
What are the different types of organic reaction?
Addition Reactions - involve the conversion of a π bond into 2 new σ bonds General form: A + B → C Eg. CH3-CH=CH-CH3 + HCl → CH3-CH2-CHCl-CH3 Substitution Reactions - involve the no change in bonding - one σ bond replaces another General form: A + B → C + D Eg. CH3-CHBr-CH2-CH3 + KOH(aq) → CH3-CH(OH)-CH2-CH3 + KBr Elimination Reactions - reverse of addition, in that two σ bonds are lost, replaced by a new π bond General form: A → B + C Eg. CH3-CH(OH)-CH2-CH3 -- conc. H2SO4 --> CH3-CH=CH-CH3 + H2O Rearrangement / Isomerisation - process in which a single substance changes structure, A → B. Such a reaction may involve changes in bond / type, though this is not necessary. These reactions are comparatively rare. Eg. CH3-CH2-CH2-C(OH)=CH2 → CH3-CH2-CH2-C(=O)-CH3 These are the four "prototypical" reactions, though several others which can be categorised as one of these are generally referred to by other names. Eg. CH3-CH(OH)-CH3 -- H2SO4 / K2Cr2O7 --> CH3-C(=O)-CH3 could be described as an elimination reaction, but would usually be called an oxidation Eg. CH3-C(=O)-CH3 -- 1. LiAlH4 2. H^+ / H2O --> CH3-CH(OH)-CH3 could be described as a (nucleophilic) addition reaction, but would usually be called a reduction Eg. CH3-C(=O)-OH + CH3-OH -- H2SO4 / Δ / reflux --> CH3-C(=O)-O-CH3 + H2O could be described as a substitution reaction, but would usually be called a condensation Another important category of organic reactions are straight-forward Lowry-Bronsted acid-base reactions: Eg. (CH3-CH2)3N + HCl → (CH3-CH2)3NH^+ + Cl^- Note that there are also some reactions that are difficult to characterise in a simple way, like the following reactions requiring catalysis: stilbene + ethylene → styrene C6H5-CH=CH-C6H5 + CH2=CH2 → 2 C6H5-CH=CH2 but-1-yne + water → butanone CH3-CH2-C≡CH + H2O → CH3-CH2-C(=O)-CH3 (this is actually an addition reaction followed by an isomerisation) CH3-CH2-C(=O)-CH3 + NH2-OH → CH3-CH2-C(=N-OH)-CH3 + H2O the pinacol to pinacolone rearrangement CH3-C(CH3)(OH)-C(CH3)(OH)-CH3 → CH3-C(CH3)2-C(=O)-CH3 which is an elimination reaction that involves an isomerisation ... I add these last few just to illustrate that the general types are a useful tool / guide for understanding organic chemistry, but they are not the be-all and end-all.
