Tert Butyl alcohol acidity

H NMR spectrum, 817 in mixed Claisen condensation, 836 2-Methyl-2-propanol, 138. See also tert-Butyl alcohol acid-catalyzed dehydration, 182 2-Methylpropene. See also Isobutene Isobutylene... 

The method is basically an application of the Wacker oxidation except that the catalyst used is palladium acetate ( Pd(AcO)2 or Pd(02CCH3)2). the solvent is acetic acid or tert-butyl alcohol and the oxygen source is the previously suggested hydrogen peroxide (H202)[17]. 

The first step of this new mechanism is exactly the same as that seen earlier for the reaction of tert butyl alcohol with hydrogen chloride—formation of an alkyloxonmm ion by proton transfer from the hydrogen halide to the alcohol Like the earlier exam pie this IS a rapid reversible Brpnsted acid-base reaction... 

These common features suggest that carbocations are key intermediates m alcohol dehydra tions just as they are m the reaction of alcohols with hydrogen halides Figure 5 6 portrays a three step mechanism for the acid catalyzed dehydration of tert butyl alcohol Steps 1 and 2 describe the generation of tert butyl cation by a process similar to that which led to its for matron as an intermediate m the reaction of tert butyl alcohol with hydrogen chloride... 

FIGURE 5 6 The El mecha nism for the acid catalyzed dehydration of tert butyl alcohol... 

We can extend the general principles of electrophilic addition to acid catalyzed hydration In the first step of the mechanism shown m Figure 6 9 proton transfer to 2 methylpropene forms tert butyl cation This is followed m step 2 by reaction of the car bocation with a molecule of water acting as a nucleophile The aUcyloxomum ion formed m this step is simply the conjugate acid of tert butyl alcohol Deprotonation of the alkyl oxonium ion m step 3 yields the alcohol and regenerates the acid catalyst... 

IS reversible with respect to reactants and products so each tiny increment of progress along the reaction coordinate is reversible Once we know the mechanism for the for ward phase of a particular reaction we also know what the intermediates and transition states must be for the reverse In particular the three step mechanism for the acid catalyzed hydration of 2 methylpropene m Figure 6 9 is the reverse of that for the acid catalyzed dehydration of tert butyl alcohol m Figure 5 6... 

We now have a new problem Where does the necessary alkene come from Alkenes are prepared from alcohols by acid catalyzed dehydration (Section 5 9) or from alkyl halides by dehydrohalogenation (Section 5 14) Because our designated starting material is tert butyl alcohol we can combine its dehydration with bromohydrm formation to give the correct sequence of steps... 

Although 2 methylpropene undergoes acid catalyzed hydration m dilute sulfuric acid to form tert butyl alcohol (Section 6 10) a different reaction occurs m more concentrated solutions of sulfuric acid Rather than form the expected alkyl hydrogen sulfate (see Sec tion 6 9) 2 methylpropene is converted to a mixture of two isomeric C Hig alkenes... 

Step 3 This step is a fast acid base reaction that follows the nucleophilic substitution Water acts as a base to remove a proton from the alkyloxonium ion to give the observed product of the reaction tert butyl alcohol... 

In a first step, D-2-amino-2-(1,4-cyclohexadienyl)acetic acid is obtained as follows. A solution of 11.0 g (72.7 mmol) of D-phenylglycine in 900 ml distilled ammonia (which has been treated with 45 mg lithium after distillation to destroy traces of moisture) is slowly diluted with 370 ml dry tert-butyl alcohol. 

Compounds with a smaller/C., and larger pKa are less acidic, whereas compounds with a larger/Ca and smaller plsimple alcohols like methanol and ethanol are about as acidic as water but substituent groups can have a significant effect, tert-Butyl alcohol is a weaker acid, for instance, and 2,2,2-trifluoroethanol is stronger. Phenols and thiols, the sulfur analogs of alcohols, are substantially more acidic than water. 

In a 500-cc. separatory funnel are placed 74 g. or 95 cc. (1 mole) of tert-butyl alcohol (Note x) and 247 cc. (3 moles) of c.p. concentrated hydrochloric acid (sp. gr. 1.19). After shaking, the layers are allowed to separate (fifteen to twenty minutes) and the upper layer is drawn off and washed first with a 5 per cent sodium bicarbonate solution, then with water until neutral to moist litmus paper (Note 2). The chloride is treated with 10 g. of calcium chloride and shaken thoroughly, then transferred to a 125-cc. distilling flask. It is then distilled, using a long water condenser. The fraction boiling at 49.5-5 20 weighs 72-82 g. (78-88 per cent of the theoretical amount). 

A Lewis acid is also necessary for the acetylation of tetracarbonylferrate using N-acetylimidazole. In the absence of a Lewis acid, a Claisen-type condensation product was formed, which has been synthesized independently from 2 moles of A-acetylimidazole with sodium terf-butanolate in tert-butyl alcohol (55% yield) or with imidazole sodium in THF (95% yield) ... 

Hofmann degradation of the nonnatural protoberberine 454 afforded the 10-membered ring base 455 (65%) in addition to the styrene-type compound (13%) (Scheme 92). Dihydroxylation of the former with N-bromosuccinimide in the presence of a large excess of hydrochloric acid and subsequent oxidation of the product diol 456 with periodic acid afforded the dialdehyde 457. On irradiation in tert-butyl alcohol 457 provided ( )-cis-alpinigenine (445) along with ( )-alpinigenine (441) as a result of endo and exo intramolecular cycloaddition, respectively, of the intermediate photodienol (221,222). 

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... 

The lesser acidity of sterically hindered alcohols such as tert-butyl alcohol arises from solvation effects. 

For the Ti(OiPr)4/silica system, the advantage of MCM-41 (a mesoporous silica) over an amorphous silica is not evident either in terms of activity or selectivity for the epoxidation of cyclohexene with H202 in tert-butyl-alcohol.148 Nevertheless, deactivation of the catalysts seems slower, although the selectivity of the recovered catalysts is also lower (allylic oxidation epoxidation = 1 1). Treatment of these solids with tartaric acid improves the properties of the Ti/silica system, but not of the Ti/MCM-41 system, although NMR,149 EXAFS,150 and IR151 data suggest that the same titanium species are present on both supports. 

N-Benzoyl meroquinene tert-butyl ester 4-Piperidineacetic acid, 1-benzoyl-3-ethenyl-, 1,1-dimethylethyl ester, (3R-cis)- (9) (52346-13-1) tert-Butyl alcohol (8) 2-Propanol, 2-methyl- (9) (75-65-0)... 

Toluene, dichloromethane, acetic acid, ammonium hydroxide, concentrated H2SO4, 5 N NaOH and 37% HCI were purchased from Mallinckrodt Inc. tetrahydrofuran, tert-butyl alcohol, anhydrous Na2S04, and NaCI were purchased from EM Science potassium tert-butoxide was purchased from Aldrich Chemical Company, Inc. hexanes was purchased from Baxter, and dry O2 was purchased from Air Products. All these reagents were used as received. 

At the outset of our studies of the reactivity of I and II, it was necessary to investigate claims that tertiary henzamides were inappropriate substrates for the Birch reduction. It had been reported that reduction of A,A-dimethylbenzamide with sodium in NH3 in the presence of tert-butyl alcohol gave benzaldehyde and a benzaldehyde-ammonia adduct. We formd that the competition between reduction of the amide group and the aromatic ring was strongly dependent on reaction variables, such as the alkali metal (type and quantity), the availability of a proton source more acidic than NH3, and reaction temperature. Reduction with potassium in NH3-THF solution at —78 °C in the presence of 1 equiv. of tert-butyl alcohol gave the cyclohexa-1,4-diene 2 in 92% isolated yield (Scheme 3). At the other extreme, reduction with lithium in NH3-THF at —33 °C in the absence of tert-butyl alcohol gave benzaldehyde and benzyl alcohol as major reaction products. ... 

The conductivity changes following pulse radiolysis of a mixture of 0.5 mM Co(acac)3, 0.04 mM HCIO4 and 0.1 M tert-butyl alcohol are shown in Figure 3 (the units of G x AA are (molecules/lOOeV) Q cm M ). The very first increase in conductivity also appears in solutions containing no Co(acac)j. The decreases in conductivity are speeded up in acid. Account for this behavior. 

SnI reactions are generally carried out in polar protlc solvents (like water, alcohol, acetic acid, etc.). The reaction between tert-butyl bromide and hydroxide Ion yields tert-butyl alcohol and follows the first order kinetics, i.e., the rate of reaetlon depends upon the concentration of only one reactant, which Is tert- butyl bromide. 

Dinitrocubane (28) has been synthesized by Eaton and co-workers via two routes both starting from cubane-l,4-dicarboxylic acid (25). The first of these routes uses diphenylphos-phoryl azide in the presence of a base and tert-butyl alcohol to effect direct conversion of the carboxylic acid (25) to the tert-butylcarbamate (26). Hydrolysis of (26) with mineral acid, followed by direct oxidation of the diamine (27) with m-CPBA, yields 1,4-diiutrocubane (28). Initial attempts to convert cubane-l,4-dicarboxylic acid (25) to 1,4-diaminocubane (27) via a Curtins rearrangement of the corresponding diacylazide (29) were abandoned due to the extremely explosive nature of the latter. However, subsequent experiments showed that treatment of the acid chloride of cubane-l,4-dicarboxylic acid with trimethylsilyl azide allows the formation of the diisocyanate (30) without prior isolation of the dangerous diacylazide (29) from solution. Oxidation of the diisocyanate (30) to 1,4-dinitrocubane (28) was achieved with dimethyldioxirane in wet acetone. Dimethyldioxirane is also reported to oxidize both the diamine (27) and its hydrochloride salt to 1,4-dinitrocubane (28) in excellent yield. ... 

Clofibrate Clofibrate, ethyl ether 2-(4-chloropheoxy)-M( -butyric acid (20.2.2), is synthesized by esterifying 2-(4-chlorophenoxy)-/yo-butyric acid (20.2.1) with ethyl alcohol. This is synthesized in a single-stage reaction from 4-chlorophenol, acetone, and chloroform in the presence of an alkali, evidently by initial formation of chlorethone-trichloro-tert-butyl alcohol, which under the reaction conditions is converted into (4-chlorophenoxy)trichloro-fert-butyl ether, and further hydrolyzed to the desired acid 20.2.1, which is further esterified with ethanol in the presence of inorganic acid [6-8]. 

Potassium methyl a-[(methoxyethylidene)amino]-p-hydroxyacrylate Propanoic acid, 2-[(1-methoxyethylidene)amino]-3-oxo-, methyl ester, ion(l-), potassium (11) (105205-36-5) Potassium tert-butoxide tert-Butyl alcohol, potassium salt (8) 2-Propanol, 2-methyl-, potassium salt (9) (865-47-4)... 

The more acidic fluorene in tert-butyl alcohol solution, or in DMSO solution, reacts by a process that involves the carbanion in equilibrium with hydrocarbon. Thus, fluorene and 9,9-dideuteriofluorene oxidize at identical rates. We have established that the oxidation of the anion of fluorene can be catalyzed by a variety of electron acceptors (v), including various nitroaromatics (18). The catalyzed oxidation rates were found to follow the rates of electron transfer measured by ESR spectroscopy in the absence of oxygen. These results established the catalyzed reaction as a free radical chain process without shedding light upon the mechanism of the uncatalyzed reaction. 

The oxidation of benzhydrol and 9-fluorenol in basic solution again shows a difference in regard to mechanism that can be primarily attributed to a difference in acidity as carbon acids. In tert-butyl alcohol benzhydrol enters into an oxidation scheme as the mono (oxy) anion. The data strongly suggest a free radical chain. Under these conditions the more acidic fluorenol or xanthenol oxidizes via carbanions or dianions. These oxidations can be catalyzed to occur via a free radical chain process by one-electron acceptors, such as nitrobenzene, and a free radical chain process may well be involved in the absence of the catalyst. 

Oxidation of Potassium Peroxide. Determination of Potassium Superoxide. Potassium peroxide was prepared by the addition of a tert-butyl alcohol solution of 90% hydrogen peroxide to potassium tert-butoxide in DMSO or tert-butyl alcohol. Oxygen absorption was followed in the standard manner (20). Analysis of solid precipitates for potassium superoxide followed exactly the method of Seyb and Kleinberg (23). Potassium superoxide formed in the oxidation of benzhydrol was determined in a 15-ml. aliquot of the oxidation solution. To this aliquot 10 ml. of diethyl phthlate was added to prevent freezing of the solution. The mixture was cooled to 0°C., and 10 ml. of acetic acid-diethyl phthlate (4 to 1) added over a period of 30 minutes with stirring. The volume of the evolved oxygen was measured. 

---