Hydration of propene in presence of dilute sulphuric acid

Hydration of Alkenes Chemistry Tutorial Want chemistry games, drills, tests and more? You need to become an Synthesis of Alcohols by Hydration of Alkenes Chemistry Tutorial Key Concepts • • The double bond (C=C) is the active site on the molecule. • Hydration of alkenes is an addition reaction. • Water adds across the alkene's double bond in the hydration reaction. • This addition follows (the H + of H 2O goes to the C atom that has the greatest number of H atoms) • Hydration of alkene reactions are used to produce industrial ethanol from ethene. • General equation for the hydration of an alkene: word equation: + water H + → chemical equation: R- C = C -R' | H | H + H-O-H H + → H | O | -H R- C - C -R' | H | H H + represents a R and R' represent hydrogen (H) or Please do not block ads on this website. No ads = no money for us = no free stuff for you! Example of Hydration of Alkene: Hydration of ethene (ethylene) to ethanol Ethene (ethylene) is an alkene with the 2C=CH 2. The active site on the ethene molecule is the double bond (C=C). In the presence of a The hydrogen atom of a water molecule will add to one of ethene's carbon atoms, and the OH from the water molecule will be added to the other carbon atom in ethene. This synthesis of ethanol from ethene is shown in the chemical equations below: Do you know this? Play the game now! Example of Hydration of Alkenes: Hydration of propene (propylene) to propanol Propene (propylene) is an alkene with the 3-H 2C=CH 2. The active ...

Introduction The direct hydration of propylene to produce isopropanol has been commercialised way back in early 1970s (Neier & Wollner, 1973). This process has several advantages over the indirect two-step hydration process that manufactures isopropanol through the formation of the corresponding sulphate via reaction with 70–80% sulphuric acid. This sulphate on subsequent hydrolysis gives isopropanol and dilute sulphuric acid has to be concentrated for recycle. The direct hydration with solid acid catalysts obviates the use of sulphuric acid and minimises the waste disposal problems, and in addition, allows the use of non-corrosive environment. The direct hydration in the presence of cation exchange resin catalyst has been studied in the past by several investigators (Hiestand, 1961; Kaiser, Beuther, Moore, & Odioso, 1962; Petrus, DeRoo, Stamhuis, & Joosten, 1986; Hirata and Ogawa, 1998). Propylene being a non-polar compound possesses very low solubility in water and tends to form a second phase if used in high concentrations. Depending on the reaction conditions employed, this second phase can be vapour phase, liquid phase or a supercritical phase. Hence, apart from the studies by Petrus et al. (1986) who investigated reacting system composed of a single liquid phase along with solid catalyst, all other experimental investigations deal with a reacting system in which most of the propylene exists in a separate phase. The reaction conditions in practice are such that a slig...

10.3 Reactions of Alkenes: Addition of Water (or Alcohol) to Alkenes Addition of Water to Alkenes (Hydration of Alkenes) An alkene does not react with pure water since water is not acidic enough to allow the hydrogen to act as an electrophile to start a reaction. However, with the presence of a small amount of an acid, the reaction does occur with a water molecule added to the double bond of alkene, and the product is an alcohol. This is the acid-catalyzed addition reaction of water to alkene (also called hydration), and this reaction has great utility in the large-scale industrial production of certain low-molecular-weight alcohols. Figure 10.3a Hydration Reaction The acid most commonly applied to catalyze this reaction is the dilute aqueous solution of sulfuric acid (H 2SO 4). Sulfuric acid dissociates completely in an aqueous solution and the hydronium ion (H 3O +) generated participates in the reaction. a strong organic acid, tosyl acid (TsOH), is sometimes used as well. The mechanism for the acid-catalyzed hydration of alkene is essentially the same as the mechanism for the addition of hydrogen halide, HX, to alkenes, and the reaction therefore also follows Markovnikov’s rule in terms of regioselectivity. The hydration of 1-methylcyclohexene and the reaction mechanism are shown below. Figure 10.3b Mechanism for acid-catalyzed hydration of alkene Sin ce a water molecule can be regarded as H—OH, the regioselectivity of alcohol product that follows Markovnikov’s rule mea...