Tertiary chlorides

Primary bromides give a precipitate of sodium bromide within 3 minutes at 25° chlorides react only when heated at 50° for up to 6 minutes. Secondary and tertiary bromides must be heated at 50° for up to 6 minutes, but tertiary chlorides do not react within this time. 

Note 1. At higher temperatures the tertiary chloride undergoes a rearrangement, catalysed by CuCl, giving H2C=C(C1)CH=CH2. In these cases the refractive index of the crude product is much higher. 

Benzylic halides resemble allylic halides m the readiness with which they form carbocations On comparing the rate of S l hydrolysis m aqueous acetone of the fol lowing two tertiary chlorides we find that the benzylic chloride reacts over 600 times faster than does tert butyl chloride... 

Up to this point in our discussion, we have considered only carbocations in which the cationic carbon can be 5p -hybridized and planar. When this hybridization cannot be achieved, die carbocations are of higher energy. In a classic experiment, Bartlett and Knox demonstrated that the tertiary chloride 1-chloroapocamphane was inert to nucleophilic substitution. Starting material was recovered unchanged even after refluxing for 48 h in ethanolic silver nitrate. The umeactivity of this compound is attributed to the structure of... 

Halide exchange, sometimes call the Finkelstein reaction, is an equilibrium process, but it is often possible to shift the equilibrium." The reaction is most often applied to the preparation of iodides and fluorides. Iodides can be prepared from chlorides or bromides by taking advantage of the fact that sodium iodide, but not the bromide or chloride, is soluble in acetone. When an alkyl chloride or bromide is treated with a solution of sodium iodide in acetone, the equilibrium is shifted by the precipitation of sodium chloride or bromide. Since the mechanism is Sn2, the reaction is much more successful for primary halides than for secondary or tertiary halides sodium iodide in acetone can be used as a test for primary bromides or chlorides. Tertiary chlorides can be converted to iodides by treatment with excess Nal in CS2, with ZnCl2 as catalyst. " Vinylic bromides give vinylic iodides with retention of configuration when treated with KI and a nickel bromide-zinc catalyst," or with KI and Cul in hot HMPA." ... 

Silyl enol ethers and silyl ketene acetals also offer both enhanced reactivity and a favorable termination step. Electrophilic attack is followed by desilylation to give an a-substituted carbonyl compound. The carbocations can be generated from tertiary chlorides and a Lewis acid, such as TiCl4. This reaction provides a method for introducing tertiary alkyl groups a to a carbonyl, a transformation that cannot be achieved by base-catalyzed alkylation because of the strong tendency for tertiary halides to undergo elimination. 

Yields of chlorides are good to excellent for primary and secondary alcohols, but a competing olefin-forming elimination process renders the method of limited value for preparing tertiary chlorides.12 An adaptation of the procedure using carbon tetrabromide allows the synthesis of alkyl bromides. Some examples are the preparation of rt-C5H11Br (97%) and C H6CH2Br (96%).12 Farncsyl bromide has been prepared in 90% yield from fame sol.23... 

Polymer molecular properties. Making a polymer of high quality is much more complicated than making butanal, for example, because the material properties of a polymer depend heavily on a number of molecular properties. For example, 1% of mistakes in a propene polymer chain can spoil the properties of a polymer completely (crystallinity for instance), while 10% of a by-product in a butanal synthesis can be removed easily by distillation. PVC contains only 0.1% defects as allylic and tertiary chlorides and this necessitates the use of a large package of stabilisers ... 

In the author s laboratories the polymerization of aldehydes, ketones, and alcohols by liquid hydrogen fluoride has been repeatedly noted. Acetaldehyde polymerizes and acetone forms polymeric substances on standing for a period of time in solution in hydrogen fluoride. If the solution is separated shortly after mixing, the acetone may be recovered. The same is true of tertiary alcohols. The peculiar action of tertiary chlorides (Simons et al., 35) probably results at least in part from polymerization. The products obtained most likely come from destruction of the polymers in the process of distillation. Benzaldehyde forms a shellac like resin when treated with hydrogen fluoride. A rather interesting polymerization reaction occurs upon treating aralkyl ketones with... 

At higher temperatures the tertiary. chloride undergoes a rearrangement under the influence of CuCl giving a chloride with a conjugated diene system. This isomer has a considerably higher refractive index. 

Secondary and tertiary chlorides can be rearranged to allenes with the aid of concentrated hydrochloric acid in the presence of cuprous chloride and ammonium chloride [57]. 

The stereochemistry of HC1 or DC1 addition to a wide variety of alkenes has been examined. Addition of HC1 to m-2,3-dideutero-2-butene affords a mixture of erythro and threo 2-chlorobutanes.40 1-Methyl-cyclopentene37 and 1,2-dimethylcyclopentene41 give almost exclusively tertiary chlorides formed by anti... 

Amett and co-workers,75 76 in a series of investigations, have determined heats of ionization (AHi) of secondary and tertiary chlorides and alcohols in SbF5-S02ClF and HS03F-SbF5-S02ClF solutions, respectively, at low temperatures. They have also measured heats of isomerizations of secondary to tertiary carbocations in the superacid media. These measured thermochemical data have been useful to determine the intrinsic thermodynamic stability of secondary and tertiary carbocations. 

If the classical structure were correct, the 2-norbornyl cation would be a usual secondary carbocation with no additional stabilization provided by c-delocalization (such as the cyclopentyl cation). The facts, however, seem to be to the contrary. Direct experimental evidence for the unusual stability of the secondary 2-norbomyl cation comes from the low-temperature solution calorimetric studies of Arnett and Petro.75 In a series of investigations, Arnett and Hofelich76 determined the heats of ionization (AHi) of secondary and tertiary chlorides in SbF5-SC>2ClF [Eq. (3.131)] and subsequently alcohols in HS03F-SbF5-SC>2ClF solutions [Eq. (3.132)]. 

Alkyl, halo, and the other substituents exhibiting a modest influence on the rate of solvolysis of the tertiary chloride were examined under the standard conditions selected as 90% aqueous acetone at 25° (Brown et al., 1957a Brown et al., 1957b). The extension of the study to highly activating and deactivating substituents required the use of special procedures for the estimation of rate data under the standard conditions. It was convenient in most instances to determine the activation parameters at suitable temperatures and calculate the rate at 25°. For more extreme variations in reactivity, as with p-methoxy- and p-nitro-phenyldimethylcarbinyl chloride, both the temperature and composition of the solvent were modified (Okamoto and Brown, 1957b). These... 

Electrophilic Constanta Derived from the Solvolysis of Tertiary Chlorides in Various Solvents... 

The two remaining isomers are a secondary chloride and a tertiary chloride ... 

Under kinetically controlled conditions the carbocation is captured at the carbon that bears the greatest share of positive charge, and the product is the tertiary chloride. 

The Kochi Reaction is a one-carbon oxidative degradation of carboxylic acids, and is a valuable alternative to the Hunsdiecker Reaction. A Pb(IV) reagent is the oxidant, and this reaction is suitable for synthesis of secondary and tertiary chlorides. 

The tertiary chloride 58 was needed for a study of the effects of electron-withdrawing groups on the Sn 1 reaction. FGI to the alcohol 59 suggests a C-C disconnection to a Grignard reagent 60 and acetone. 

---