Pentyl chlorides, reaction

Isomerization is observed with higher alkyl halides, as in Friedel-Crafts reactions isopropylphosphonic dichloride is stated to be the sole product from n-propyl chloride,190,191 and terf-pentyl chloride undergoes C-C fission, yielding the tert-butyl acid.193 On reduction by lithium tetrahydroaluminate the phosphonic chloride formed from w-butyl chloride gives a primary phosphine that is shown by 31P-nuclear magnetic resonance to consist of n- and sec-butylphosphine in the proportions 5 95 and the product from n-octyl chloride was similarly shown to contain all four position isomers.194... 

Alkyl halides add to alkenes in the presence of AICI3 yields are the highest when tertiary halides are used. Predict the outcome of the reaction of rerr-pentyl chloride (l-chloro-2,2-dimethylpropane) with propene and specify the mechanistic steps. 

When terf-pentyl alcohol was reacted with acetic anhydride and perchloric or tetrafluoroboric acids, the reaction proceeded via the more stable trisubstituted alkene (21) under thermodynamic control and the reaction product was mainly a 2,3,4,6-tetramethylpyrylium salt (25). However, with terf-pentyl chloride, acetyl chloride and aluminum chloride or antimony pentachloride, the diacetylation occurred under kinetic control the alkene equilibration proceeds very fast with these Lewis acids so that the product (26) is derived from the more reaetive but less stable disubstituted alkene (22) 63,64 formulas below, the intermediate monoaeetylation products... 

These reactions provide an interesting contrast in mechanisms. The n-butyl bromide synthesis proceeds by an Sj 2 mechanism, whereas f-pentyl chloride is prepared by an S l reaction. 

Alkyl Group. Tertiary alkyl halides may be used in solvolyses with confidence that the reactions are proceeding by the Sj jl mechanism. Two compounds that allow you to examine the possible effects of the structure of the alkyl group on reaction rates are 2-chloro-2-methylpropane (ferf-butyl chloride) and 2[Pg.484]

The Friedel—Crafts alkjiation reaction is an electrophilic aromatic substitution that attaches an alkyl group to the aromatic ring. It is named for Charles Friedel (1832-1899) and James M. Crafts (1839—1917), who discovered it by acddent when they tried to synthesize pentyl chloride from pentyl iodide through reaction with aluminum chloride in an aromatic solvent. Instead of the hoped-for chloride, substituted aromatic hydrocarbons appeared. The Friedel-Crafts reaction is closely related to bromination and chlorination of benzene. If we treat benzene with isopropyl bromide in the hope that a nucleophilic attack of benzene on isopropyl bromide will produce isopropylbenzene (cumene), we are sure to be disappointed (Fig. 14.34). Benzene is by no means a strong nucleophile and isopropyl bromide can scarcely be described as a powerful electrophile. The proposed reaction is utterly hopeless, and ftuls to give product. 

The yield of ethyl n -pentyl ether formed from the reduction of 1-pentanal by Et3SiH/TFA in ethanol is 57% after 6-8 hours at 50-60°.327 The yield of product increases to 72% when one equivalent of ethyl orthoformate and some anhydrous hydrogen chloride are added to the reaction medium.327 Presumably, this reduces the amount of free water in the reaction medium. 

Di-w -pentyl Ether [TMSI-Catalyzed Reduction of an Aldehyde to a Symmetrical Ether].314 A mixture of sodium iodide (0.15 g, 1 mmol), 1-pentanal (1.06 mL, 10 mmol), and trimethylsilyl chloride (2.0 mL, 15.4 mmol) was stirred in MeCN (5.0 mL) at room temperature for 10 minutes, after which 1,1,3,3-tetramethyldisiloxane (TMDO, 1.79 mL, 10 mmol) was added. When the exothermic reaction had ended (30 minutes), a solution of 2.5 N HF in MeOH (30 mL) was added to the reaction mixture, which was then refluxed for 5 minutes. Work-up was carried out by diluting the solution with CH2CI2 (40 mL), washing with water (30 mL) and saturated aqueous NaHC03 solution (20 mL), drying, and evaporating the solvents. Crude di-n-pentyl ether was purified by distillation 0.65 g (84%) bp 185-1897760 Torr. 

The reaction may be carried out either by the addition of nitrosyl chloride or by the generation of this reagent in situ from pentyl nitrite and hydrochloric acid. 

Carboxy-4-methyl-5-pentyl-2-furanpropanoic acid (273), isolated from blood and urine, is a hitherto unknown class of metabolic compound. The structure of (273) has recently been confirmed by synthesis (80CB699). 2,4,5-Trialkyl substituted furan-3-carboxylic acids have been synthesized from acyloin and /3-ketoesters by treatment with zinc chloride. By analogy with this synthetic route, the reaction of acetoin with 3-oxoadipic acid dimethyl ester was found to yield the 2,3-dimethylfuran (274). The dimethyl ester (275) was prepared by condensation of 3-chloro-2-octanone with 3-oxoadipic acid dimethyl ester and was shown to be identical with the dimethyl ester of the natural product. 

Aluminum chloride, 15 Arenediazonium tetrafluoroborates, 19 Rhodium(II) carboxylates, 266 Tris(dimethylamino)sulfonium difluoro-trimethylsilicate, 336 Asymmetric reactions Addition reactions to carbonyl groups Bis(2,4-dimethyl-3-pentyl) tartrate, 36 (S)-( + )-2-Methoxymethylpyrrolidine, 180... 

To prepare the solid benzenediazonium chloride or sulphate, the reaction is conducted in the absence of water as far as possible. The source of nitrous acid is one of its organic esters (e.g. pentyl nitrite) and a solution of hydrogen chloride gas in absolute ethanol upon the addition of ether only the diazonium salt is precipitated as a crystalline solid. 

In Section 5.2.5, we discussed the Friedel-Crafts alkylation of benzene with 2-chloropentane. This reaction includes a Wagner-Meerwein reaction in conjunction with other elementary reactions. The Lewis acid catalyst A1C13 first converts the chloride into the 2-pentyl cation A (Figure 11.3). Cation A then rearranges into the isomeric 3-pentyl cation B, in part or perhaps to the extent that the equilibrium ratio is reached. The new carbenium ion B is not significantly more stable than the original one (A),... 

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