THE ABSENCE OF REARRANGEMENT OF THE ISOBUTYL GROUP DURING THE FORMATION OF ISOBUTYLMAGNESIUM BROMIDE AND ITS RELATION TO THE THEORY OF REARRANGEMENTS¹

Abstract

The ready change of isobutyl compounds to tertiary butyl compounds has long been known. The interconversion of the bromides has been thoroughly studied.2 The results of these studies indicate that (1) rearrangement of isobutyl bromide to tertiary butyl bromide at high temperatures in the vapor phase may occur by way of dissociation and addition of hydrogen bromide (Brunei) but (2) this rearrangement takes place more readily in the liquid phase and at temperatures at which there is no dissociation into hydrogen bromide and olefin. Heating the vapor of isobutyl bromide at 140°for fourteen hours produces no rearrangement while heating the liquid at the same temperature for one hour gives a 55% conversion to the tertiary bromide (Michael). The isobutyl "ions" readily rearrange by the transfer of an electron pair and its proton.3Other isobutyl compounds undergo similar rearrangements. Isobutyl iodide reacts with silver acetate in the absence of a solvent to give isobutyl acetate while the presence of acetic acid as a solvent makes tertiary butyl acetate the chief product.4 Similar results are obtained with silver cyanate.6 With silver oxide in the presence of acetic acid, isobutyl bromide yields tertiary butyl alcohol and tertiary butyl acetate (Linnemann). An even more interesting example of this transformation is the conversion of isobutyl iodide to tertiary butyl chloride by the action of iodine monochloride (Linnemann). This reaction apparently occurs as follows (CH3)2CHCH2 Í:The two ions left are peculiar in that each is the result of a "chemical reaction" rather than of an ordinary "ionization."Each is present only in 1 Presented by Albert R. Lux in partial fulfilment of the requirements for the Ph.D.

Rearrangement in Alkyl Groups during Substitution Reactions

“…In a series of papers published between 1932 and 1938 this mechanism was illustrated (177, [179][180][181][182][183][184][185][186][187], and it was further shown that in those reactions where an octet of electrons appeared to be preserved, rearrangement did not occur. Thus, while neopentyl alcohol reacted with hydrogen bromide to give t-amyl bromide (186), the amide trimethylacetamide, (CH&CCONH2 CHI CH3 H * .…”

Fanweed Seed Oil

“…The mixed methyl esters of the fatty acids were then subjected to fractional distillation at 1 mm. pressure with a fractionating column of the type described by Whitmore and Lux (9), equipped with a total-reflux partial-takeoff distilling head and packed with single-turn glass helices. The bath and jacket were electrically heated, and the temperature was controlled by water-cooled rheostats.…”

Preparation and some physical properties of 2,2,4,4-tetramethylpentane

“…It was then dried over calcium chloride and distilled through a 150-by 2-cm helix-packed column [2]. After a forerun of diisobutylene (150 to 450 ml), there was obtained 595 to 687 ml of crude 2,2,4,4-tetramethylpentane (boiling range 119° to 124 0 C).…”

“…Twenty-eight hundred milliliters of crude 2,2,4,4-tetramethylpentane prepared as described above was purified by subj ecting it to the following treatment: Ten washings with concentrated sulfuric acid; two washings with water; one washing with 5-percent aqueous sodium bicarbonate; one washing with water, drying with calcium chloride, refluxing over sodium, distillation, passing through a column (100 by 2 cm) of silica gel; five washings with sulfuric acid; one washing with water; one washing of bicarbonate; one washing with water, drying with calcium chloride, refluxing over sodium, and distillation through a 150-by 2-cm column [2]. The fraction which boiled at 122 0 to 123 0 C was collected, and amounted to 2,210 ml.…”

“…The product was distilled in a 10-by gOO-mm column packed with glass helices [2]. The temperature steadily rose during distillation, and four fractions were obtained.…”