2-Chlorobutane involving

Another experiment of the competition type involves the comparison of the reactivity of different atoms in the same molecule. For example, gas-phase chlorination of butane can lead to 1- or 2-chlorobutane. The relative reactivity k /k of the primary and secondaiy hydrogens is the sort of information that helps to characterize the details of the reaction process. 

The arenium ion/(R)-(— )-2-chlorobutane adducts. A crucial question concerns the chemical identity and the relative spatial arrangement of the components of a microsolvated system, two features of paramount importance to assess the kinetic and the mechanistic role of the corresponding ion-dipole pairs in solution. In the example reported in this section, Cacace and coworkers consider the ion-molecule complexes involved in the classical Friedel-Crafts alkylation of arenes." " At 300 K and under FT-ICR conditions, the benzenium ion CeH reacts with 2-chlorobutane C4H9CI to give the CloHj5 ion with a rate constant of 5 X 10 cm molecule corresponding to a collision efficiency of 2.5% (equations (33) or (34)). ... 

Lund and coworkers [131] pioneered the use of aromatic anion radicals as mediators in a study of the catalytic reduction of bromobenzene by the electrogenerated anion radical of chrysene. Other early investigations involved the catalytic reduction of 1-bromo- and 1-chlorobutane by the anion radicals of trans-stilhene and anthracene [132], of 1-chlorohexane and 6-chloro-l-hexene by the naphthalene anion radical [133], and of 1-chlorooctane by the phenanthrene anion radical [134]. Simonet and coworkers [135] pointed out that a catalytically formed alkyl radical can react with an aromatic anion radical to form an alkylated aromatic hydrocarbon. Additional, comparatively recent work has centered on electron transfer between aromatic anion radicals and l,2-dichloro-l,2-diphenylethane [136], on reductive coupling of tert-butyl bromide with azobenzene, quinoxaline, and anthracene [137], and on the reactions of aromatic anion radicals with substituted benzyl chlorides [138], with... 

In the formation of 1-chlorobutane, an intermediate primary radical is involved, and there are no stereochemical consequences. However, the secondary radical involved in 2-chlorobutane formation is planar, and when it abstracts a chlorine atom from a chlorine molecule it can do so from either side with equal probability. The result is formation of a racemic product, ( )-2-chlorobutane. 

The reaction of (R)-2-chlorobutane with chlorine to give 2,3-dichlorobutane involves initial conversion to an intermediate free radical (consult Sec. 2.13). This free radical can react with chlorine molecules from the top face to give meso-2,3-dichlorobutane, or the bottom face to give (2R,3R)-dichlorobutane. 

This was the basis of the approach by Chessick et al. (1954, 1955) and Zettlemoyer etal. (1958), which involved the use of a series of immersion liquids such as butyl derivatives differing only in their polar groups 1-butanol, 2-butanol, butanal, 1-aminobutane, 1-chlorobutane, butanoic acid. With the polar surfaces studied (rutile, CaF2, Aerosil, alumina), an approximately linear relation was found between the energy of immersion and the dipole moment. The slope gave directly the average field strength (for instance, 820 V//rm 1 on a rutile titanium (tv) oxide) and the... 

Ibophyllidine, iboxyphylline, and their close relatives have also lent themselves to synthesis by the Kuehne biomimetic approach. The first essay in this area involved the synthesis of desethyl-ibophyllidine (674), which had recently been isolated from Tabernaemontana albiflora (380), With 4-chlorobutanal, the indoloazepine ester 560 condensed to give an epimeric mixture of intermediate quaternary salts, formulated as 727a, either of which, on reaction with triethylamine, gave desethyl-ibophyllidine (674) via a reactive secodine derivative (Scheme 108) (331). 

The photolysis data indicate the product ratio, 2,3-C4H8Cl2/l,3-C4H8C12 = 3.2. Since all of the chlorobutane products (including 2-C4H9Cl), are formed by appropriate combinations of H3C—CH—Cl and H2C—CH2—Cl radicals, it can be deduced from this ratio, ignoring possible differences in steric factors, that abstraction of a H atom from the a-carbon of ethyl chloride is 7.4 times more probable than abstraction from the /2-carbon. This comparatively low concentration of the -radical accounts for the failure to observe 1,4-dichlorobutane as a product in these experiments since its concentration would be (1/7.4)2 times the 2,3-dichlorobutane concentration and therefore too small to be observed by our analytical methods. The small quantity of 1-chlorobutane observed as a photolysis product can be explained similarly since it would also involve the /2-chloroethyl radical. 

Coldham et al. reported on a cascade reaction sequences involving condensation, cyclization, intramolecular dipolar cycloaddition for preparation of fused tricyclic heterocycles which can be converted in two steps to a 1,3-oxazine present in some yuzurimine-type Daphniphyllum alkaloids under some conditions [57], In another study, addition of hydroxylamine to substituted 4-chlorobutanals gives intermediate nitrones that imdergo tandem cyclization and then intramolecular dipolar cycloaddition to give the core... 

The first step in ionic liquid synthesis involves quaternization or alkylation of 1-methylimidazole using chlorobutane for example to obtain the cation (Eq 2.26). ... 

---