Markovnikoffs Rule

MANOMETRIC ASSAY METHODS MAPPING SUBSTRATE INTERACTIONS USING KINETIC DATA MARCUS EQUATION MARCUS RATE THEORY MARKOV CHAIN Markovnikoff rule,... 

In common with simple thiols and (9, (9-dialkyl phosphorodithioates, phosphinodithioic acids add to alkenes according to the Markovnikoff rule (propenenitrile is a possible exception to this behaviour) and even in the absence of a catalyst (equation 44). In the presence of sodium methoxide, anti-Markovnikoff behaviour is often observed as the result of Michael addition of the acid anion (equation 45). Addition of the acids to otherwise saturated nitriles leads, following acidolysis of intermediate species, to thiocarboxamides and the phosphinothioyl halide (Scheme. 50). 

Two orientations of the addition process are possible for the reaction with the unsymmetrical reagents HCl, H2O, and H2SO4. MarkovnikofFs rule tells us that the major product is the one where the H of the reagent attaches to the carbon of the double bond that has two hydrogens attached. The other doubly bonded carbon has fewer (zero) hydrogens attached ... 

Problem 12.16. Show how carbocation stability explains Markovnikoffs rule in the addition of HCl to propene. 

Ans. We start by writing the mechanism for each of the two orientations in the addition of HCl. One of the pathways proceeds via a secondary carbocation while the other proceeds via a primary carbocation. Two competing reactions occur. The faster reaction is the one that proceeds via the more stable carbocation. The overall result is that much more 2-chloropropane is formed than 1-chloropropane. This is the result predicted by Markovnikoffs rule. 

Ans. There is No Reaction for (ft). All others undergo reaction. MarkovnikofFs rule is applicable to (a) and (d) since both alkene and reagent are unsymmetrical. 

Ans. The chemistry of the triple bond is simply the chemistry of the double bond multiplied by 2. The triple bond reacts with the same reagents that react with the double bond. The reaction proceeds first to yield an alkene and then the alkene reacts with more of the reagent. Each addition follows the Markovnikoff rule. 

Ans. The major and minor products are 2-hydroxypropane and 1-hydroxypropane, respectively. (The lUPAC names are 2-propanol and 1-propanol, as will be discussed in Chap. 13.) The mechanism for formation of each product is shown below. 2-Propanol is the major product, as predicted by the Markovnikoff rule, because it is formed by the pathway that proceeds via formation of the most stable carbocation (2 ° instead of 1 °). 

Additions of this type do not always follow the Markovnikoff rule. Under certain conditions the reaction may involve the free radicals H and A , in which case the opposite (anti-Markovnikoff) effect occurs. The rule is named for the Russian chemist Vladimir Vasilyevich Markovnikoff (1838-1904). 

Mark-Houwink equation phys chem The relationship between intrinsic viscosity and molecular weight for homogeneous linear polymers mark hau.wigk i.kwa-zhon ) Markovnikoffs rule org chem In an addition reaction, the additive molecule RH adds as H and R, with the R going to the carbon atom with the lesser number of hydrogen atoms bonded to It. mar kov-na.kofs, rijl)... 

The hydration of olefins can be considered a hydrolysis reaction since the olefin on reaction with sulfuric acid yields an alkyl sulfuric acid which on subsequent hydrolysis yields the alcohol. Sulfuric acid adds to olefins in accordance with the Markovnikoff rule as illustrated in Eq. (2) for isobutylene. 

Maleic acid, 338 Maionic ester, 380 Markovnikoff s rule, 96 Mass spectroscopy, 247/T Mechanism, alcohol dehydration, 92 alkane halogenation, 56 benzyne, 217 El and E2, UOff SnI and Sn2, 122 ... 

The regioselective addition of HX to alkenes produces the more substituted alkyl halide, which is known as the Markovnikov (Markovnikoff) product. Markovnikov s rule states that on addition of HX to an alkene, H attaches to the carbon with fewest alkyl groups and X attaches to the carbon with most alkyl groups . This can be explained by the formation of the most stable intermediate carbocation. 

Arts. Markovnikoff s rule is used The H fragment from the reagent adds to that carbon of the double bond which already has more hydrogens. The rule is often stated as The rich (in hydrogens) get richer. For addition of HCl to 1-butene, C-1 receives H from HCl since it has more hydrogens than C-2. 

In the case of higher alkenes (more than two carbon atoms) several isomeric products are possible. The particular isomer produced depends on the stability of the alternative intermediates and this is summarized empirically by Markovnikoff s rule. See also addition reaction. 

Markovnikoff s rule /mar-koff-ni-koffs/ A rule that predicts the quantities of the products formed when an acid (HA) adds to the double bond in an alkene. If the alkene is not symmetrical two products may result for instance (CH3)2C CH2 can yield either (CH3)2HCCH2A or (CH3)2ACCH3. The rule states that the major product will be the one in which the hydrogen atom attaches itself to the carbon atom with the larger number of hydrogen atoms. In the example above, therefore, the major product is (CH3)2ACCH3. 

Remember also to assign a positive charge to the molecule before submitting it to calculation. This is usually done in the menus where you select the type of calculation. Compare your results for the two calculations. Which carbocation will lead to the major product Do your results agree with the prediction made by Markovnikoff s Rule ... 

In 1869 Vladimir Vasil evich Markovnikoff (1838-1904), a pupil of Butlerov, proposed the rule subsequently named after him concerning the addition of hydrogen halides to unsaturated hydrocarbons. In his words If an unsymmetrically constituted hydrocarbon unites with a hydrohalogen acid, the halogen adds to the less hydrogenated carbon atom. .. . This rule provided the first prediction of the course of a reaction in terms of the structure of one of the reactants. 

Mercaptans add to olefins in good yields according to Markovnikoff s rule in the presence of sulfuric acid, boron trifluoride, or sulfur and also in an anti-Markovnikoff fashion in the presence of peroxides or via photochemical means. Vinyl chloride and allyl alcohol give lower yields than conjugated olehnic ketones, aldehydes, esters, and cyanides. Cupric acetate or triethylamine can be used as a catalyst for the reaction of methyl mercaptan with acrolein to give p-mercaptopropionaldehyde in 84% yield. Allene reacts homolytically with methanethiol to give allyl sulfide and the 1,3- and 1,2-dimethyl-thiopropanes. 

Malonic ester synthesis, 60, 74 Mannich reaction, 157 Markovnikoff addition, 178 anti-, 178, 180 Markovnikoff s rule, 29 McFadyen-Stevens reaction, 50 Michael condensation, 157 Michael reaction, 94... 

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