Zaitsevs rule or saytzeffs rule, saytzevs rule is an empirical rule for predicting the favored alkene products in elimination reactions. Elimination reactions mechanisms e2 elimination zaitsev saytzeff rule cm1501 from cm 1501 at national university of singapore. Zaitsev of the university of kazan russia set forth a gen eralization describing the regioselectivity of eliminations. In todays lab we will be focusing on e1 and e2 reactions, including the analysis of the products for either zaitsev or hofmann. When more than one alkene product is possible from the base induced elimination of an alkyl halide, the most highly substituted most stable alkene is usually the major product. If the elimination takes place by the e1 mechanism, the reaction is much more likely to compete with the s n 1 reaction and a mixture of substitution and elimination products is likely. The zaitsev elimination the alternative regiochemistry for elimination giving the most substituted alkene as the major product was reported by zaitsev in 1875 for the eliminations of alkyl iodides by base. Zaitsevs rule is an empirical rule for predicting the favored alkene products in elimination.
Upon graduating from the university of kazan, zaitsev worked 186265 in the laboratories of a. Mechanisms that do not involve a carbocation intermediate may react through other mechanisms that have other regioselectivities not dictated by markovnikovs rule, such as free radical addition. Zaitsev, aleksandr mikhailovich born june 20 july 2, 1841, in kazan. Zaitsevs or saytzevs anglicized spelling rule is an empirical rule used to predict regioselectivity of 1,2elimination reactions occurring via e1 mechanism or via e2 mechanism it states that in a regioselective e1 or e2 reaction the major product is the more stable alkene, i. Zaitsev, aleksandr article about zaitsev, aleksandr by. Spontaneous dehydrochlorination against the zaitsev rule the free radical addition of arylsulfonyl chlorides to. Certain haloalkanes can undergo elimination in two different ways giving a mixture of two products. No, you can treat an alkane with a bulky base that may result in the hydrogen being removed on the less substituted carbon.
The use of 3 different electrophiles is due to the different products we are testing for. According to saytzeffs rule also known as zaitsevs rule, during dehydration, more substituted alkene olefin is formed as a major product, since greater the substitution of double bond greater is the stability of alkene. A commentary on the origins of zaitsevs rule david e. Kuzmins book, chockfull of novelties and presenting a most remarkable new plan for black, can be called a revelation as well. Zaitsevs or saytzevs anglicized spelling rule is an empirical rule used to predict regioselectivity of 1,2elimination reactions occurring via e1 mechanism or via e2 mechanism. Zaitsevs rule or saytseffs rule, saytzev rule is an empirical. Zaitsev and hofmann e1 and e2 elimination reactions intro. Elimination reactions mechanisms e2 elimination zaitsev.
During this experiment we used the same nucleophile and reacted it with 3 different electrophiles. Pointers on free radical reactions protecting groups protecting groups. Markovnikov rule definition is a statement in chemistry. Elimination reactions zaitsevs rule chemistry libretexts. Notes of a russian sniper by vassili zaitsev, hardcover. Zaitsev writes in a humble, personable, engaging manner. Despite doubts concerning some of the details of the fighting, and its initial appearance under communist auspices, as a literary work, notes of a sniper is comparable to e. Zaitsevs rule summarizes the results of numerous experiments in which alkene mixtures were produced by elimination. How to apply saytzeff rule to predict alkene major product from elimination reactions h2chemhacks duration. The iupac name of the alcohol undergoing dehydration reaction is 2,3dimethylpentan3ol.
The zaitsev product or the more substituted alkene product is more stable than the less. With a foreword by us champion fabiano caruana, seventime russian champion peter, and grandmaster igor zaitsev himself. Former world champion garry kasparov once called the zaitsev system a revelation. Sledges with the old breed, and as a memoir of courage. Reading vassili zaitsevs memoir of his nightmarish experiences as a sniper at stalingrad is both a frightening and fascinating experience. The rule does not apply to eliminations other than dehydrohalogenation. Discover book depositorys huge selection of vassili zaitsev books online. The alkene formed in greatest amount is the one that corresponds to removal of the hydrogen from the. According to the rule, when an hx molecule x is a halogen atom is separated from an alkyl halide, the hydrogen is lost from the carbon atom with the least number of hydrogen atoms, that is, from the least hydrogenated one. Saytzeff rule implies that baseinduced eliminations e 2 will lead predominantly to the olefin in which the double bond is more highly substituted, i.
Zaitsev rule article about zaitsev rule by the free. It states that in a regioselective e1 or e2 reaction the major product is the more stable alkene, i. Introduction to free radical substitution reactions introduction to oxidative cleavage reactions. The major product of an elimination reaction tends to. Zaitsevs rule also spelled saytzeffs rule helps us predict the major product. In such cases, the major product is the more stable productthe one with the more substituted double bond. Lewis, university of wisconsin, eau claire as students at kazan, markovnikov and zaitsev were the recipients of a chemical education that was one of the best in europe. The freeradical addition of arylsulfonyl chlorides to. And so zaitsevs rule is kind of analogous to markovnikovs rule. Illustrated glossary of organic chemistry zaitsevs rule. Hofmanns rule and zaitsevs rule chemistry libretexts. Such reactions are said to be antimarkovnikov, since the halogen adds to the less substituted carbon, the opposite of a markovnikov reaction. However, not all of these products will be of equal stability.
Zaitsevs rule or saytzeffs rule is an empirical rule for predicting the favored alkene products in elimination reactions. Zaitsev and hofmann e1 and e2 elimination reactions. Zaitsev had cited popovs paper in previous work and worked at the university of kazan, and was thus probably aware of popovs proposed rule. Example of zaitsevs rule, eliminations, assignment help. Zaitsevs rule an empirical rule for predicting the favoured alkene product s in elimination reactions. Now first, ill just tell you the rule, then we can think a little bit about why it works. In its original form, zaitsevs rule stated that the alkene formed in greatest amount is the one that. Based on this trend, zaitsev stated, the alkene formed in greatest amount is the one that. Zaitsev rule the principle governing the separation of the elements of a hydrogen halide from alkyl halides. The major product of a dehydrohalogenation elimination reaction is the more highly substituted alkene. In an elimination reaction, the major product formed will be a more.
Zaitsevs rule for e2 and e1 reactions more free lessons at. Saytzeff rule implies that baseinduced eliminations e2 will lead predominantly to the olefin in which the double bond is more highly. Markovnikov rule definition of markovnikov rule by. Violation of zaitsevs rules student doctor network. Zaitsevs principal commands were the group of soviet forces in germany and the southern military districts of the soviet union second world war. While at the university of kazan, russian chemist alexander zaitsev studied a variety of different elimination reactions and observed a general trend in the resulting alkenes. Zaitsev rule definition chemistry glossary definition of zaitsev rule. Zaitsevs rule simply means that the more substituted carbon will lose a hydrogen. Reaction regiochemistry markovnikov, zaitsev and hofmann. The more stable alkene is the one that will form, and this will always be the most highly substituted alkene. Elimination reactions mechanisms e2 elimination zaitsev saytzeff rule cm1501.
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