Hofmann s rule

In the absence of considerations mentioned below, orientation is statistical and is determined by the number of p hydrogens available (therefore Hofmann s rule is followed). For example, sec-butyl acetate gives 55-62% 1-butene and 38-45% 2-butene, which is close to the 3 2 distribution predicted by the number of hydrogens available. ... 

The mechanism is usually E2. Hofmann s rule is generally obeyed by acyclic and Zaitsev s rule by cyclohexyl substrates (p. 1315). In certain cases, where the molecule is highly hindered, a five-membered Ei mechanism, similar to that in 17-7, has been shown to operate. That is, the OH in these cases does not attract the P... 

Tertiary halides undergo elimination most easily. Eliminations of chlorides, bromides, and iodides follow Zaitsev s rule, except for a few cases where steric effects are important (for an example, see p. 1316). Eliminations of fluorides follow Hofmann s rule (p. 1316). 

A -Oxides give alkenes via a -elimination under heating. This reaction obeys Hofmann s Rule. 

Hofmann s Rule implies that steric effects have the greatest influence on the outcome of the Hofmann or similar eliminations. The loss of the (3-hydrogen occurs preferably from the most unhindered (least substituted) position [-CH3 > -CH2-R > -CH(R2)]. The product alkene with fewer substitutents will predominate. 

Hofmann s Rule is valid for all intramolecular eliminations and for the Hofmann Elimination. Most bimolecular eliminations will follow Saytzeff s Rule. 

Generally, dehydrogenation prevailed in secondary amines when treated with one equivalent of IOB in dichloromethane in this way ACt-butylbenzylamine gave its imine (PhCH = NBu , 88%), whereas pyrrolidine was converted into a mixture of 1-pyrroline and its trimer. Hydrogen elimination followed Hofmann s rule, for example in the following transformation [41] ... 

Using Zaitsev s Rule and Hofmann s Rule to Predict Elimination Products... 

In this example, 1-pentene and 2-pentene are possible products. The reaction produces almost exclusively 1-pentene, the less highly substituted product. This elimination reaction follows Hofmann s rule ... 

Again, Hofmann s rule predicts that the major pathway will be the one that produces the less highly substituted alkene. An example is shown in the following equation ... 

In this case a /3-hydrogen (a hydrogen on the /3-carbon) could be lost from either the ethyl or the propyl group. In accord with Hofmann s rule the less highly substituted alkene, ethene, is found to be the major product. 

This elimination reaction follows Hofmann s rule, so the less substituted alkene should be the major product. 

Hofmann eliminations follow Hofmann s rule the less highly substituted product is the major product. 

Understand Zaitsev s rule and Hofmann s rule and when each applies. (Problem 9.17)... 

Hofmann s rule (Section 9.4) The major product of an elimination reaction has fewer alkyl groups bonded to foe carbons of the double bond (foe less highly substituted product). The Hofmann elimination follows this rule. 

Traditionally, these two opposite preferences—for the more or the less substituted alkenes—have been called Saytsev s rule and Hofmann s rule, respectively. You will see these names used (along with a number of alternative spellings—acceptable for Saytsev, whose... 

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