Alcohols, R-OH

Bands due to O-H stretching and bending vibrations and C-O stretching vibrations are observed. 

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CO. Alkynes will react with carbon monoxide in the presence of a metal carbonyl (e.g. Ni(CO)4) and water to give prop>enoic acids (R-CH = CH-C02H), with alcohols (R OH) to give propenoic esters, RCH CHC02R and with amines (R NH2) to give propenoic amides RCHrCHCONHR. Using alternative catalysts, e.g. Fe(CO)5, alkynes and carbon monoxide will produce cyclopentadienones or hydroquinols. A commercially important variation of this reaction is hydroformyiation (the 0x0 reaction ). 

When Ihis sequence is applied to carbohydrales fhe firsl slep lakes place mtramolecu lady to yield a cyclic hemiacelal The second slep is mtermolecular requires an alcohol R"OH as a reaclanl and proceeds readily only m fhe presence of an acid calalysl An oxygen slabilized carbocalion is an mlermediale... 

When this sequence is applied to carbohydrates, the first step takes place intramoleai-larly to yield a cyclic hemiacetal. The second step is intermolecular, requires an alcohol R"OH as a reactant, and proceeds readily only in the presence of an acid catalyst. An oxygen-stabilized carbocation is an intermediate. 

If an alcohol R OH is used as solvent instead of water, the corresponding ester 7 can be obtained directly. In analogous reactions with ammonia or amines (R NHa) the amides 8 and 9 respectively are accessible. 

Those steps are reversible reactions, with the equilibrium shifted to the left. However the overall reaction can be carried out in good yield since the /3-ketoester 2 is converted into the conjugate base 6 by the lost alkoxide 5 the ester is more acidic than the alcohol R OH 7 ... 

The ketocarbene 4 that is generated by loss of Na from the a-diazo ketone, and that has an electron-sextet, rearranges to the more stable ketene 2 by a nucleophilic 1,2-shift of substituent R. The ketene thus formed corresponds to the isocyanate product of the related Curtius reaction. The ketene can further react with nucleophilic agents, that add to the C=0-double bond. For example by reaction with water a carboxylic acid 3 is formed, while from reaction with an alcohol R -OH an ester 5 is obtained directly. The reaction with ammonia or an amine R -NHa leads to formation of a carboxylic amide 6 or 7 ... 

We ll see in Section 21.3 that carboxylic acids (RCO2H) react with alcohols (R OH) to form esters (RC02R )- Suppose that ( )-lactic acid reacts with CH3OH to form the ester, methyl lactate. What stereochemistry would you expect the product(s) to have What is the relationship of the products ... 

An ester is formed by the reaction between an acid, RCOOH, and an alcohol, R OH, to form an ester RCOOR and water. The reaction is carried out in an inert solvent. 

Transesterification has been carried out with phase-transfer catalysis, without an added solvent. In another procedure, RCOOR are converted to RCOOR" by treatment of the ester and an alcohol R OH with n-BuLi, which converts the R"OH to R"OLi. ... 

If an alcohol R OH is used instead of water, the ester RCH2COOR is isolated... 

The reagent titanocene dichloride reduces carboxylic esters in a different manner from that of 10-86, 19-36, or 19-38. The products are the alkane RCH3 and the alcohol R OH. The mechanism probably involves an alkene intermediate. Aromatic acids can be reduced to methylbenzenes by a procedure involving refluxing first with trichlorosilane in MeCN, then with tripropylamine added, and finally with KOH and MeOH (after removal of the MeCN). The following sequence has been suggested ... 

Since acidification liberates CO and the alcohol (45), the reaction is essentially reversible. The reaction presumably occurs via the substitution [usually a S, reaction 139)] of the coordinated alkoxide by CO, which then adds the alkoxide. In an extension of this reaction, the photolysis of solutions of [RCo(salen)H20] (R = Me, Et, n-Pr, n-Bu) in alcohols R OH (R = Me,... 

Figure 15 The diversity alcohols (R -OH and carboxylic acids (R2)-C02H used to synthesize compounds represented by 18 and 19. (From Ref. 30.)...

The reactions of carbonyl compounds with alcohols, R OH, to yield hemi-acetals (22),... 

The stoichiometry of these reactions can be controlled by modulating the concentration of hydroxyl groups on the surface of silica. When starting with the tetra-alkyl complex, subsequent reaction with an alcohol R OH (Equation(4)) is necessary this generally occurs under conditions mild enough to maintain the anchoring bond SiO—M. 

A potentially useful variant of the synthesis of some Mo(CHR)(NAr)(OR )2 complexes (R=CMe3 or CMe2Ph) consists of addition of two equivalents of a relatively acidic alcohol (R OH=a fluorinated alcohol or phenol) to Mo(NAr)(N-t-Bu)(CH2R)2 [78,79], a variation of the reaction of that type that was first reported in 1989 [80]. The more basic t-butylimido ligand is protonated selectively. This synthesis avoids the addition of triflic acid to Mo(NAr)2(CH2R)2 to give Mo(CHR)(N-t-Bu)(triflate)2(dimethoxyethane), the universal precursor to any Mo(CHR)(NAr)(OR )2 complex. Unfortunately, the method does not appear to succeed when R OH does not have a relatively high pK,. 

TRANSITION STATE STABILIZATION Table A5.15 Constants for basic cleavage of p /3-cyclodextrin and alcohols, R-OH." -nitrophenyl hexanoate in 81 presence of... 

Succinic diesters and acrylic esters are formed through insertion of the olefin into the Pd-C bond of an alkoxycarbonylpalladium species X - Pd - C02R (ensuing from the reaction between PdX2, CO and an alcohol R OH used as an external nucleophile, Scheme 3). Further carbon monoxide insertion, followed by nucleophilic displacement by R OH, then leads to the succinic diester (Scheme 3, path a). /J-H elimination may also take place to give the a./J-unsaluralcd ester (Scheme 3, path b). This latter pathway is followed at low carbon monoxide partial pressures. 

This reaction occurs in soils amended with Flamprop-methyl [205], Benzoyl-prop-ethyl, and Diclofop-methyl [206]. As the names of these pesticides indicate, R is CH3 or CH2CH3, respectively. The second product of the conversion is presumably the non-toxic alcohol [R -OH]. 

Carbonic acid esters (alkoxycarbonyl derivatives) are diesters of general formula R-O-CO-O-R. A single mechanism operates in the HO -catalyzed (and presumably also in the enzyme-catalyzed) hydrolysis of carbonic acid esters, namely a rate-determining addition of the base to the carbonyl C-atom to form an intermediate whose breakdown yields the drug (ROH), C02, and an alcohol (R OH) (Fig. 8.7,a) [153],... 

The stability of these compounds is maximal at pH 4 - 6, and decreases very sharply at lower and higher pH values, and the mechanism and products of the reaction differed with pH. In the neutral range, hydrolysis yielded the aromatic sulfonamide and the ester, whereas, under acid catalysis in the low pH range, the products were the AT-acyl sulfonamide and an alcohol (R OH, Fig. 11.9). Of particular interest is that the tm values for hydrolysis of the N-sulfonyl imidates in 80% human plasma were 3-150 times lower than in buffer solution at identical pH and temperature. This was taken as evidence for enzymatic hydrolysis by human plasma hydrolases. Hydrolysis under these conditions yielded the sulfonamide and the ester in quantitative amounts. 

Cleavage of C—O bonds by direct electron transfer from a cathode is usually difficult because of the negative reduction potential of the bond. Therefore, the reduction of aliphatic alcohols (R-OH) to the corresponding hydrocarbons (R-H) is often carried out by the transformation of hydroxyl groups to good leaving groups such as halides (X = Br, I), methanesulfonates (OMs), and... 

Alcohols R —OH methyl alcohol CH3 —OH ethyl alcohol CgHs — OH... 

Alcoholysis. A reaction between an alcohol and another organic compound that forms a- new substance plus water. Typical examples include the reaction of alcohol (R-OH) with itself or another alcohol (R -OH) to give an ether (R-O-R ) and water. 

Fatty esters. Esters made from fatty acids (RCOOH) by reaction with a linear alcohol (R OH), generally methyl alcohol, giving the fatty ester (RCOOR ). 

The reactivity of Group 6 allenylidenes [M(=C=C=CR R )(CO)5] (M = Cr, W R and R = alkyl, aryl or H) towards nucleophiles is clearly dominated by the additions at the electrophilic a-carbon. In this sense, the most common reaction of these complexes (usually generated in sim) is the addition of alcohols R OH across the C =Cp bond to afford Fischer-type a,p-unsaturated alkoxycarbene... 

Labile and Exchangeable protons. Protons in groups such as alcohols (R-OH) amines (R-NH-), carboxylic acids (RCOOFl), thiols (R-SH) and to a lesser extent amides (R-CO-NH-) are classified as labile or readily exchangeable protons. 

If one or more of the hydrogen atoms of a non-metal hydride are replaced formally with another group, R—e.g., alkyl residues—then derived compounds of the type R-XHn-i, R-XHn-2-R, etc., are obtained. In this way, alcohols (R-OH) and ethers (R-O-R) are derived from water (H2O) primary amines (R-NH2), secondary amines (R-NH-R) and tertiary amines (R-N-R R") amines are obtained from ammonia (NH3) and thiols (R-SH) and thioethers (R-S-R ) arise from hydrogen sulfide (H2S). Polar groups such as -OH and -NH2 are found as substituents in many organic compounds. As such groups are much more reactive than the hydrocarbon structures to which they are attached, they are referred to as functional groups. 

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