Addition of water

Addition of water (H—OH) to alkenes also occurs according to Markovnikov s rule. Hydrogen (— H) of water is added to the carbon atom of the double bond that already has the greater number of hydrogen atoms. —OH is added to the carbon atom of the double bond that has the smaller number of hydrogen atoms. In this reaction, H2SO4 is used as catalyst, and a monoalcohol is produced. 

Butane is a saturated hydrocarbon, so it doesn t undergo addition reactions. 

2 moles of a mixture methane (CH ) and ethylene (C2H4) react completely with 32 grams of Br2. What is the mole percentage of methane In the mixture  

CH4 is a saturated hydrocarbon. Thus, only C2H4 reacts with Br2 in an addition reaction. 

Although the addition of H2O to an alkyne resembles the acid-catalyzed addition of H2O to an alkene in some ways, an important difference exists. In the presence of strong acid or Hg catalyst, the elements of H2O add to the triple bond, but the initial addition product, an enol, is unstable and rearranges to a product containing a carbonyl group—that is, a C=0. A carbonyl compound having two alkyl groups bonded to the C=0 carbon is called a ketone. 

Because an enol contains both a C=C and a hydroxy group, the name enol comes from alkene + alcohol. 

HgS04 is often used in the hydration of internal alkynes as well, because hydration can be carried out under milder reaction conditions. 

Internal alkynes undergo hydration with concentrated acid, whereas terminal alkynes require the presence of an additional Hg catalyst—usually HgS04—-to yield methyl ketones by Mar-kovnikov addition of HgO. 

Let s first examine the conversion of a general enol A to the carbonyl compound B. A and B are called tautomers A is the enol form and B is the keto form of the tautomer. 

Maleic anhydride or its derivatives undergo the usual reactions of an olefin. Maleic acid, for instance, can be hydrated to yield malic acid 9/ This 

The naturally occurring form is /-malic acid. The latter occurs in a number of fruits including apple, apricot, banana, cherry, and grape. It may be remembered that MA was first isolated from the decomposition of malic acid. 

When /-malic acid is desired, hydration may be carried out using microorganisms. Degen et have recently claimed a 75% yield of /-malic acid when hydration of fumaric acid was assisted by paracobactrum Nos. 743, 745, and 746. 

To obtain /-malic acid from a usual synthesis giving a mixture of d and / stereoisomers, a resolution is necessary. This is generally achieved by crystallization of the cinchonine salt of malic acid. By this method, cinchonine, which is an optically active amine, forms a mixture of diastereomeric salts with different solubility characteristics. Other optically active amines may also be utilized. 

The natural occurrence of malic acid gives it an easy acceptability as a food additive. It has been included on the GRAS list by the U.S. Food and Drug Administration.Common applications of malic acid to this end are 

The asymmetric addition of water or ammonia onto olefins is one of the dream-reactions on organic synthesis and represents one of the (largely unsolved) problems of catalysis. Enzymes called hydratases or ammonia lyases can catalyze this reaction. However, they only act on activated alkenes, such as a,p-unsaturated carboxylic acids, and their substrate tolerance is rather narrow and only allow minor structural variations of their natural substrate(s), which severely limits their application in organic synthesis. 

Fumarase [EC 4.2.1.2] and malease [EC 4.2.1.31] catalyze the stereospecific addition of water onto carbon-carbon double bonds conjugated with a carboxylic acid [1570]. The analogous addition of ammonia is catalyzed by aspartase [EC 4.3.1.1], 3-methylaspartase [1571], and phenylalamine ammonia lyase [EC 4.3.1.5], 

The hydration of propylene with sulfuric acid catalyst in high-temperature water was investigated using a flow reaction system. The major product is isopropanol. A biopolymer-metal complex, wool-supported palladium-iron complex (wool-Pd-Fe), has been found to be a highly active catalyst for the hydration of some alkenes to the corresponding alcohols. The yield is greatly affected by the Pd/Fe molar ratio in the wool-Pd-Fe complex catalyst and the catalyst can be reused several times without remarkable change in the catalytic activity.  

Oxymercuration/demercuration provides a milder alternative for the conventional acid-catalyzed hydration of alkenes. The reaction also provides the Markovnikov regiochemistry for unsymmetiical alkenes. Interestingly, an enantioselective/inverse phase-transfer catalysis (IPTC) reaction for the Markovnikov hydration of double bonds by an oxymercuration-demercuration reaction with cyclodextrins as catalysts was recently reported. Relative to the more common phase-transfer 

Oxytelluration of olefins with PhTeBrs or Ph2Te2-Br2 in aqueous THF generates (P-hydroxyalkyl)aryltelluiium dihalides. The reaction is tran -stereospecific in the case of cw-2-butene and cis- and trans-4-octenes and regiospecific in the cases of all terminal olefins. Their reactions with reducing agents in aqueous sodium hydroxide generate the Markovnikov hydration products. 

When aldehydes react with water, unstable hydrate compounds are formed. In this process, the hydrogen atom of water is bonded to the oxygen in the carbonyl group and the hydroxide group of water is bonded to the carbon atom of the carbonyl group. 

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Addition of water gives the hydrated nitrate Cu(N03)2.3H2O, the product obtained when copper (or the +2 oxide or carbonate) is dissolved in nitric acid. Attempts to dehydrate the hydrated nitrate, for example by gently heating in vacuo, yield a basic nitrate, not the anhydrous salt. 

Add 15 g, of chloroacetic acid to 300 ml. of aqueous ammonia solution d, o-88o) contained in a 750 ml. conical flask. (The manipulation of the concentrated ammonia should preferably be carried out in a fume-cupboard, and great care taken to avoid ammonia fumes.) Cork the flask loosely and set aside overnight at room temperature. Now concentrate the solution to about 30 ml. by distillation under reduced pressure. For this purpose, place the solution in a suitable distilling-flask with some fragments of unglazed porcelain, fit a capillary tube to the neck of the flask, and connect the flask through a water-condenser and receiver to a water-pump then heat the flask carefully on a water-bath. Make the concentrated solution up to 40 ml. by the addition of water, filter, and then add 250 ml. of methanol. Cool the solution in ice-water, stir well, and set aside for ca. I hour, when the precipitation of the glycine will be complete. 

In an experiment, a slight excess of the hydride is employed to ensure the complete reduction the unused hydride must then be destroyed. This can be done by the cautious addition of (rt) water, or (6) ordinary undried ether, which will ensure that the supply of water is both small and gradual, or (c) an ester such as ethyl acetate, which will be reduced to ethanol. The first of these methods, namely the addition of water, is hazardous and should be avoided. 

J Some sodium salts (particularly sodium oxalate) may be precipitated, due to their low solubility in NaOH solution. The salt should be redissolved by the addition of water before the subsequent distillatfon. 

The excess of unchanged acetic anhydride is then hydrolysed by the addition of water, and the total free acetic acid estimated by titration with standard NaOH solution. Simultaneously a control experiment is performed identical with the above except that the alcohol is omitted. The difference in the volumes of NaOH solution required in the two experiments is equivalent to the difference in the amount of acetic add formed, i.e., to the acetic acid used in the actual acetylation. If the molecular weight of the alcohol is known, the number of hydroxyl groups can then be calculated. 

Some liquids are practically immiscible e.g., water and mercury), whilst others e.g., water and ethyl alcohol or acetone) mix with one another in all proportions. Many examples are known, however, in which the liquids are partially miscible with one another. If, for example, water be added to ether or if ether be added to water and the mixture shaken, solution will take place up to a certain point beyond this point further addition of water on the one hand, or of ether on the other, will result in the formation of two liquid layers, one consisting of a saturated solution of water in ether and the other a saturated solution of ether in water. Two such mutually saturated solutions in equilibrium at a particular temperature are called conjugate solutions. It must be mentioned that there is no essential theoretical difference between liquids of partial and complete miscibility for, as wdll be shown below, the one may pass into the other with change of experimental conditions, such as temperature and, less frequently, of pressure. 

By refluxing a mixture of the acid (1 mol), alcohol (3-4 mols), dry benzene (375 ml.) and concentrated sulphuric acid (58-60 g.). The ester as formed passes into the benzene layer. Upon the addition of water, separating the benzene layer, and distilling the latter (after washing and dr3dng), benzene and alcohol pass over first, followed by the ester, for example ... 

When polymers or other water-soluble substances are present in the sample, it is advantageous to add a small amount of chloroform to the initial reaction mixture after the subsequent addition of water, a two-phase system results which may be titrated in the usual way to a starch end point or by observing the disappearance of the iodine colour in the chloroform layer. 

The state of aqueous solutions of nitric acid In strongly acidic solutions water is a weaker base than its behaviour in dilute solutions would predict, for it is almost unprotonated in concentrated nitric acid, and only partially protonated in concentrated sulphuric acid. The addition of water to nitric acid affects the equilibrium leading to the formation of the nitronium and nitrate ions ( 2.2.1). The intensity of the peak in the Raman spectrum associated with the nitronium ion decreases with the progressive addition of water, and the peak is absent from the spectrum of solutions containing more than about 5% of water a similar effect has been observed in the infra-red spectrum. ... 

Addition of water to solutions of nitric acid in 90% sulphuric acid reduces rates of nitration. Between 90% and 85% sulphuric acid the decrease in rate parallels the accompanying fall in the concentration of nitronium ions. This is good evidence for the operation of the nitronium ion as the nitrating agent, both in solutions more acidic than 90% and in weakly diluted solutions in which nitronium ion is still spectroscopically detectable. 

The addition of water depresses zeroth-order rates of nitration, although the effect is very weak compared with that of nitrate ions concentrations of 6x io mol 1 of water, and 4X io mol 1 of potassium nitrate halve the rates of reaction under similar conditions. In moderate concentrations water anticatalyses nitration under zeroth-order conditions without changing the kinetic form. This effect is shown below (table 3.5) for the nitration of toluene in nitromethane. More strikingly, the addition of larger proportions of water modifies the kinetic... 

For nitrations carried out in nitric acid, the anticatalytic influence of nitrous acid was also demonstrated. The effect was smaller, and consequently its kinetic form was not established with certainty. Further, the more powerful type of anticatalysis did not appear at higher concentrations (up to 0-23 mol 1 ) of nitrous acid. The addition of water (up to 5 % by volume) greatly reduced the range of concentration of nitrous acid which anticatalysed nitration in a manner resembling that required by the inverse square-root law, and more quickly introduced the more powerful type of anticatalytic effect. 

In originally considering the 5 3 mechanism, involving base catalysis, Bennett, Brand, James, Saunders and Williams were trying to account for the small increase in nitrating power which accompanies the addition of water, up to about 10%, to sulphuric acid. The dilution increases the concentration of the bisulphate ion, which was believed to be the base involved (along with molecular sulphuric acid itself). The correct explanation of the effect has already been given ( 2.3.2). 

Reduction of 3-Nitro-2-cholestene. - Zinc dust (dOOmg) was added in portions during 1 hr to a stirred warm (4(fC) suspension of 250 mg of 3-nitro-2-cholestene in 15mL of acetic acid and 0.5 ml of water. After 4 hr reflux, the mixture was Altered hot and the zinc washed well with hot HOAc. Addition of water and extraction with ether gave 116mg of product."... 

Hate 1. To a suspension of 0.40 mol of lithium amide in 400 ml of liquid NH3 (see Chapter II, Exp. 11) was added 0.30 mol of HCECCH20-tert.-CitHg Subsequently 0.46 mol of CjHsBr was introduced in 30 min. After an additional 1 h the NH3 was removed by placing the flask in a water-bath at 40°C. Addition of water, extraction with diethyl ether and distillation gave C2H C=CCH20-tert.-C,H in more than 85% yield. 

Note 1. The amine was added to ensure that after addition of water no traces of acid were liberated (from unconverted HejSiCl) the acid would catalyze the addition of water to the triple bond. 

The previous product was added to LiAlH (6 eq.) in THF. The solution was heated at reflux for 1 h. The excess hydride was destroyed by dropwise addition of water and the resulting mixture filtered through Celite. The filtrate was diluted with EtOAc, washed with brine and dried (Na2S04). The product was an oil (3.4 g, 98%). 

Addition of water to the double bond of an alkene takes place in aqueous acid Addition occurs according to Mar kovnikov s rule A carbocation is an in termediate and is captured by a mole cule of water acting as a nucleophile... 

First stage Formation of the tetrahedral intermediate by nucleophilic addition of water to the carbonyl group... 

Step 2 Nucleophilic addition of water to protonated form of ester... 

In acid the nitnle is protonated on nitrogen Nucleophilic addition of water yields an imino acid... 

Dissolve 3.913 g (NH4)2Ce(N03)g in 10 ml H2SO4, stir 2 min, cautiously introduce 15 ml water and again stir 2 min. Repeat addition of water and stirring until all the salt has dissolved, then dilute to volume. 

The enzyme fumarase catalyzes the stereospecific addition of water to fumarate to form L-malate. A standard solution of fumarase, with a concentration of 0.150 tM, gave a rate of reaction of 2.00 tM mim under conditions in which the concentration of the substrate was significantly greater than K. The rate of reaction for a sample, under identical conditions, was found to be 1.15 tM mimh What is the concentration of fumarase in the sample ... 

Acetaldehyde [75-07-0] (ethanal), CH CHO, was first prepared by Scheele ia 1774, by the action of manganese dioxide [1313-13-9] and sulfuric acid [7664-93-9] on ethanol [64-17-5]. The stmcture of acetaldehyde was estabhshed in 1835 by Liebig from a pure sample prepared by oxidising ethyl alcohol with chromic acid. Liebig named the compound "aldehyde" from the Latin words translated as al(cohol) dehyd(rogenated). The formation of acetaldehyde by the addition of water [7732-18-5] to acetylene [74-86-2] was observed by Kutscherow] in 1881. 

Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7] is currendy an important intermediate in the production of acetic acid, acetic anhydride [108-24-7] ethyl acetate [141-78-6] peracetic acid [79-21 -0] pentaerythritol [115-77-5] chloral [302-17-0], glyoxal [107-22-2], aLkylamines, and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1]. In 1989, it was estimated that 28 companies having more than 98% of the wodd s 2.5 megaton per year plant capacity used the Wacker-Hoechst processes for the direct oxidation of ethylene. 

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