Tert-butyl alcohol dimer

Would you expect the OH stretching frequencies in 2,3-dimethyl-2,3-butanediol to be shifted from the value in tert-butyl alcohol, even in dilute solution. Identify the OH stretching frequencies in the diol and compare them to tert-butyl alcohol. Rationalize your observations by comparing the geometry of the diol with those of tert-butyl alcohol and tert-butyl alcohol dimer. 

Use SpartanView to measure the 0-H bond distance and identify the 0-H stretching vibration of (ert-hutyl alcohol. Next, measure the O—H bond distances and identify the two stretching vibrations in tert-butyl alcohol dimer. How does dimerization affect the hydrogen-bonded -OH group, and how does it affect the other -OH group ... 

Butane, 1,4-diiodo-, 30, 33 2-Butanone, 3-acetamido-, 33,1 n-BuTYLACETYLENE, 30, IS tert-Butyl alcohol, 30, 19, 20 32, 20 ierl-Butylbenzene, 32, 91 n-Butyl bromide, 30, 16 tert-Butyl hypochlorite, 32, 20 n-Butyl iodide, 30, 34 Butylketene dimer, 31, 71 -ter -Butylphenyl salicylate, 32, 26 Butyrchloral, 33, IS Butyric acid, a, y-dicyano-o-phenyl-, ethyl ester, 30, 80... 

Selectivity to ETBE is usually very high and the main side reactions are isobutene dimerization with formation of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene (DIB), ethanol self-condensation to diethyl ether (DEE), water addition to isobutene with formation of tert-butyl alcohol (TBA) and the etherification of linear butenes, if present, to produce ethyl sec-butyl ether (ESBE). 

The absorption of isobutene in subazeotropic aqueous ethanol, to give ETBE and tert-butyl alcohol (TBA) was investigated [58]. The experiments were conducted in a stainless steel autoclave of one liter capacity. The catalyst used was Amberlyst-15, which is an acidic, macroporous cation exchange resin, in the form of spherical beads. In the ETBE synthesis reaction using ethanol and isobutene, the side reactions are the dimerization of isobutene to form diisobutene and the formation of diethyl ether. These byproducts show a tendency to increase with an increase in reaction temperature. Hence, the... 

The values of the enthalpy obtained do not depend on the model chosen for the dimer, as shown by Lussan (19) in a comprehensive summary of the possible theoretical treatments of the NMR data. Lussan demonstrates the form of the equilibrium constant calculation in the case of (1) monomer-dimer (open or cyclic), (2) monomer-cyclic trimer, and (3) monomer-higher acyclic multimers in the two cases of (3a) all K s equal and (3b) ki for monomer-dimer equilibrium unique, k s for higher multimers all equal. He then takes the experimental curves for a number of alcohols in carbon tetrachloride and achieves a reasonable fit to the data up to 0.6 mole fraction by using one or the other of the theoretical relationships. In some cases two sets of theoretical points are plotted on the same graph as the experimental data both are a good fit in the low concentration region, up to 0.1 mole fraction. Above this concentration one or the other of the theoretical curves is much closer to the experimental curve. Lussan implies that hypothesis 3b may be a more accurate fit to the data in the more concentrated solutions. Methanol, ethanol, 2-methyl-2-propanol (tert-butyl alcohol) and 2,2,4-trimethyl-3-pentanol follow the curve for equilibrium 3a, while 2,2,4,4-tetramethyl-3-pentanol fits the monomer-dimer data. Lussan points out that the behavior of the latter alcohol fits in with that of two similar heavily substituted tertiary alcohols which have been found by infrared methods to form only dimers. 

Oxygenates such as methanol, methyl tertiary butyl ether (MTBE) and/or tert-butyl alcohol (TBA) are used as "selectivator" to improve selectivity of the dimerization reaction while avoiding formation of heavier oligomers. 

Tert-butyl alcohol (TBA) is the largest monohydric alcohol fully solvated in water. A level of micro-heterogeneity and mixing in water-TBA systems is under debate [42-43]. EFP reliably predicts strengths of hydrogen bonding in various water-TBA dimers, as compared to the MP2/6-311-I— -G(d,p) calculations [35] (see Fig. 5.3). Intermolecular distances obtained by the EFP and MP2 methods differ by less than 0.1 A. Stabilities of the dimers by EFP are within 0.8 kcal/mol of the MP2 stabilities, with the largest error observed for the first (W-TBAa) water-TBA dimer. 

The hnear dimerization of isoprene with alcohols also continues to be of inter-est,[27],[8i] [85] rough correlation between the yield of octadienyl ether and the acidity of the alcohol was noted.f " Thus, trifluoroethanol (pX, 12.39) and methanol (pX, 15.09) give high yields ethanol (pX 15.93), n-propanol (pX 16.1), and n-butanol (pX 16.1) give moderate yields while tert-butyl alcohol (pX >19) does not afford a hnear dimer. 

As the product Al(OPr )(OBu )2 is found to be dimeric it was suggested that aluminium atoms on being surrounded by bulky isopropoxy and tert-butoxy groups in a structure of the type (2-1), are shielded so effectively that the lone pair orbital of the oxygen atom of another tert-butyl alcohol molecule cannot approach sufficiently close to the d orbitals of aluminium for the interaction to be initiated. A finer difference in susceptibilities to steric factors was further demonstrated by the fact that with aluminium ethoxide, some further (albeit extremely slow) replacement was possible. 

Similar to the alcoholysis reaction of tetrameric aluminium isopropoxide with tert-butyl alcohol, the alcoholysis reaction of dimeric aluminium tris(dimethyl amide) with rert-butyl alcohol is also slow owing to steric factors. However, the amide route affords finally the tris product [Al(OBu )3], (Eq. 2.108) instead of the mixed product of the type Al2(OBu )5(OPr ) which was finally obtained in the reaction of [Al(OIV)3]4 with an excess of Bu OH. 

Typical isobutylene, as suppHed to the butyl mbber process, has a purity in the range of 95—99%, and includes varying amounts of propene, 1-butene, 2-butene, isobutylene dimer, and tert-huty alcohol, and trace quantities of a variety of oxygen-containing compounds, depending on the process employed. 

The heterogeneous catalytic system iron phthalocyanine (7) immobilized on silica and tert-butyl hydroperoxide, TBHP, has been proposed for allylic oxidation reactions (10). This catalytic system has shown good activity in the oxidation of 2,3,6-trimethylphenol for the production of 1,4-trimethylbenzoquinone (yield > 80%), a vitamin E precursor (11), and in the oxidation of alkynes and propargylic alcohols to a,p-acetylenic ketones (yields > 60%) (12). A 43% yield of 2-cyclohexen-l-one was obtained (10) over the p-oxo dimeric form of iron tetrasulfophthalocyanine (7a) immobilized on silica using TBHP as oxidant and CH3CN as solvent however, the catalyst deactivated under reaction conditions. 

Both the ally lie alcohol and tert-hutyX hydroperoxide are achiral, but the product epoxide is formed in high optical purity. This is possible because the catalyst, titanium tetraiso-propoxide, forms a chiral (possibly dimeric [36]) complex with resolved diethyl tartrate [(+)-DET] which binds the two achiral reagents together in the reactive complex. The two enantiotopic faces of the allylic double bond become diastereotopic in the chiral complex and react at different rates with the tert-butyl hydroperoxide. Many other examples may be found in recent reviews [31, 37-39]. 

Chiral epoxides are important intermediates in organic synthesis. A benchmark classic in the area of asymmetric catalytic oxidation is the Sharpless epoxidation of allylic alcohols in which a complex of titanium and tartrate salt is the active catalyst [273]. Its success is due to its ease of execution and the ready availability of reagents. A wide variety of primary allylic alcohols are epoxidized in >90% optical yield and 70-90% chemical yield using tert-butyl hydroperoxide as the oxygen donor and titanium-isopropoxide-diethyltartrate (DET) as the catalyst (Fig. 4.97). In order for this reaction to be catalytic, the exclusion of water is absolutely essential. This is achieved by adding 3 A or 4 A molecular sieves. The catalytic cycle is identical to that for titanium epoxidations discussed above (see Fig. 4.20) and the actual catalytic species is believed to be a 2 2 titanium(IV) tartrate dimer (see Fig. 4.98). The key step is the preferential transfer of oxygen from a coordinated alkylperoxo moiety to one enantioface of a coordinated allylic alcohol. For further information the reader is referred to the many reviews that have been written on this reaction [274, 275]. 

This dimer reacts as two molecules of free 5- alkyli-soxazolyl-3-isocyanate with secondary amines or with alcohols to give the corresponding ureas or carbamates useful as agrochemicals or fine chemicals intermediates. For example, 3-amino-5-tert-butyl isoxazole is a key intermediate for 3- 5-tert-butylisoxazolyl)-1,1-dimethyl urea (common name Isouron) which is useful as a herbicide for sugar cane and other crops (Ref. 180) [Scheme 127]. 

Hydroalkoxylation reactions refer to the addition of an alcohol over an insaturation. This highly atom economical process is potentially a straightforward and clean access to ethers, and the reaction is successfully applied at the industrial level for the production of MTBE (methyl terf-butyl ether) and ETBE (ethyl tert-butyl ether) from isobutylene and methanol or ethanol. If this transformation is well known with activated olefins (reaction referred to a Michael addition), a real challenge is the synthesis of ethers from unactivated olefins. Veiy few reactions involving carbohydrates or polyols have been reported to date and most of them involve isobutylene as this substituted olefin is prompt to generate stabilized carbenium ion under acidic conditions. Dimerization reactions of the alcohol or isobutylene are the main side reactions that have to be avoided in order to reach high selectivities into the desired ethers. ... 

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