Alcohol with isomeric

The student will doubtless be aware of the fact that methyl, ethyl, n-propyl and iso propyl alcohols are completely miscible with water. The solubilities of the higher aloohols decrease progressively as the carbon content increases. The solubilities of all types of alcohols with five carbon atoms or more are quite small. For the isomeric butyl alcohols the solubilities (g. per 100 g. of water at 20°) are n-butyl, 8 iso-butyl, 23 scc.-butyl, 13 ierl.-butyl, completely miscible. 

Acetylene is also protected as propargyl alcohol (300)[2H], which is depro-tected by hydrolysis with a base, or oxidation with MnOi and alkaline hydrolysis. Sometimes, propargyl alcohols are isomerized to enals. Propargyl alcohol (300) reacts with 3-chloropyridazine (301) and EtiNH to give 3-diethylami-noindolizine (303) in one step via the enal 302[2I2]. Similarly, propargyl alcohol reacts with 2-halopyridines and secondary amines. 2-Methyl-3-butyn-2-ol (304) is another masked acetylene, and is unmasked by treatment with KOH or NaOH in butanol[205,206,213-2l5] or in situ with a phase-transfer cata-lyst[2l6]. 

Eriedel-Crafts alkylation of ben2ene with isomeric amyl alcohols proceeds with some rearrangement. Eor example, both 2- and 3-pentanol gave the identical product mixture (60% 2-phenylpentane, 31% 3-phenylpentane, and 9% / f/-pentylben2ene) from reaction with ben2ene in the presence of BE catalyst (85). 

Bromomethyl-5-methylthiophene gives normal displacement products with amines but it is isomerized on attempted reaction with copper(I) cyanide (Scheme 59) 48MI30200. Whereas 2-hydroxymethylthiophene reacts normally with hydrogen halides to give 2-halomethylthiophenes, reaction of 2-hydroxymethylfuran (2-furfuryl alcohol) with hydrochloric acid results in formation of laevulinic acid (151). 2-Furfuryl alcohol derivatives are... 

The reaction of alkoxyenyne alcohols 201 with diols in the presence of a catalytic pairHgO/Bp3 (35°C, 1 h) gives 2-(4-methyl-2-oxo-3-pentenyl)-l,3-dioxacyclanes (202) in a yield of up to 64% (75ZOR516). Apparently, the reaction starts with isomerization of alkoxyenyne alcohol to alkoxydivinylketone (203) which adds a diol... 

Roussel lijs studied ilie oxidation products of cedrenc, from which he obtained the ketone eedrone, C,5lJ., 0, by means of chromic acid. On rediKitlon ihis yields an alcohol, isocedrol, isomeric with cedrol,... 

Isomerization of the double bond in allylic alcohols may result in aldehydes or ketones (I07a). The reaction can have synthetic value (8bJ3c). If isomerization is desired, palladium is probably the preferred catalyst, operated best under hydrogen-poor conditions (/47fl). Allylic ethers can be converted to alcohols by isomerization with (Ph3P)3RhCl at pH 2 to the vinyl ether, which undergoes hydrolysis (36a). 

The number of isomeric homologues of benzene with formula Cg n 6-f2n asymptotically proportional to the number of isomeric alcohols with proportionality factor [r(p ) + (p)r(p ) J/2. 

Draw and name the eight isomeric alcohols with formula C5H120. 

A careful investigation of the extent of isomeric products formed by reaction of several alcohols with thionyl chloride has been reported. The product compositions for several of the alcohols are given below. Identify the structural features that promote isomerization and show how each of the rearranged products is formed. 

In Section 3.5 on alkene isomerization, it was mentioned that Li and co-workers reported a RuCl2(PPh3)3-catalyzed shuffling of functional groups of allylic alcohols in water (Eq. 3.35).140 Since the reaction proceeds through an enol intermediate, allyl alcohols can thus be considered as enol equivalents.203 This has been developed into an aldol-type reaction by reacting allyl alcohols with aldehyde (Scheme 3.11).204 The presence of In(OAc)3 promoted the aldol reaction with a-vinylbenzyl alcohol and aldehyde.205... 

When the number of carbon atoms in an alcohol molecule is greater than 2, several isomers are possible, depending on the location of the —OH group as well as on the nature of the carbon chain. For example, the structural formulas of four isomeric alcohols with the formula C4HyOH are given in Table 21-6. 

The scope and limitations of the Fe(CO)s-catalyzed isomerization of allylic alcohols was investigated in detail. This study revealed that the treatment of secondary allylic alcohols with 10-20 mol% Fe(CO)s at 110-125 °C for 2-6 h gave isomerized ketones in 60-80% yield with >95% purity.31... 

Denmark pursued intramolecular alkyne hydrosilylation in the context of generating stereodefined vinylsilanes for cross-coupling chemistry (Scheme 21). Cyclic siloxanes from platinum-catalyzed hydrosilylation were used in a coupling reaction, affording good yields with a variety of aryl iodides.84 The three steps are mutually compatible and can be carried out as a one-pot hydro-arylation of propargylic alcohols. The isomeric trans-exo-dig addition was also achieved. Despite the fact that many catalysts for terminal alkyne hydrosilylation react poorly with internal alkynes, the group found that ruthenium(n) chloride arene complexes—which provide complete selectivity for trans-... 

Bianchini and coworkers [126] found a difference in the chemoselectivity between the metals Fe, Ru, and Os in the complexes [M(H2)H(P(CH2CH2PPh2)3)]-BPh4 in the hydrogenation of benzylideneacetone by transfer from iso-propanol. The Fe and Ru catalysts reduced the 0=0 bond to give the allyl alcohol, with Ru more active than iron (TOF 79 IT1 at 60°C for Ru versus 13 IT1 at 80°C for Fe), while the Os catalyst first reduced the 0=0 bond but then catalyzed isomerization of the allyl alcohol to give the saturated ketone (TOF 55 IT1 at 80°C). The difference in reactivity was attributed to the weak binding of the alkene of the allyl alcohol to Fe and Ru relative to Os in these complexes. A variety of selec-tivities was noted for other unsaturated ketones, whereas unsaturated aldehydes were not hydrogenated. 

Acid Effect in Grafting With Isomeric Alcohols. With the isomeric propanols and butanols, some unexpected results were obtained both in the presence and absence of acid (Table II). 

The influence of cosurfactant structure is best illustrated by using various isomeric alcohols with the same chain length. This is shown in Figure 4 for the system water, benzene, potassium oleate and amylic alcohols (25). The mass ratio of potassion oleate to COH is 3 5 and the temperature was 22°C. 

Treatment of the alcohol ( ) with trifluoromethylsulfonic anhydride (triflic anhydride) at -78 C afforded the ester (1 ) which could be isolated and characterized. We knew from previous experience (2J that sulfonyl esters vicinal to an isopropylidene acetal are relatively stable. The triflate T,) reacted cleanly with potassium azide and 18-crown-6 in dichloromethane at room temperature. The crystalline product [68% overall from (1 )] was not the azide ( ) but the isomeric A -triazoline ( )- Clearly the initially formed azide (18) had undergone intramolecular 1,3-cyclo-addition to the double bond of the unsaturated ester (21- ). The stereochemistry of the triazoline (1 ), determined by proton nmr spectroscopy, showed that the reaction was stereospecific. There are several known examples of this reaction ( ), including one in the carbohydrate series ( ). When the triazoline was treated with sodium ethoxide ( ) the diazoester ( ) was rapidly formed by ring-opening and was isolated in 85% yield, Hydrogenolysis of the diazo group of (M) gave the required pyrrolidine ester ( ) (90%). 

A range of allylic alcohols are isomerized with good enantioselection by Rh(I)/PF-P(o-To1)2 (Tab. 4.1). As the steric demand of the alkyl group on the olefin increases, the enantioselectivity increases (entries 1-3). In contrast, the stereoselectivity does not appear to be particularly sensitive to either steric or electronic variations in the aryl substituent (entries 3-6). 

Physical Form. Liquid a mixture of closely related isomeric, primary alcohols with branched chains... 

Heck-type phenylation of allyl alcohol with Ph2BiCl proceeded in the presence of Pd(OAc)2 to afford an isomerized product, 3-phenylpropanal, in 61% yield together with biphenyl (Scheme 8) [23]. The reaction required air (or oxygen) for catalytic conversion. A similar reaction with Ph2SbCl was more efficient and afforded 3-phenylpropanal in 94% yield. 

In order to obtain some information on the reaction mechanism, the reaction of propargylic alcohol with acetone in the presence of a catalytic amount of 5a was monitored. The result indicated that the catalytic formation of the hexadienone proceeded via the initial isomerization of propargylic alcohol to dnnamaldehyde followed by aldol condensation between the produced aldehyde and acetone, and then dehydration. In fad, heating of propargylic alcohol in the presence of a catalytic amount of 5a gave only dnnamaldehyde (Scheme 7.41), and the separate reaction ofcinna-... 

Id (Scheme 3) . This was prepared via the corresponding phosphite, which can be synthesized by reaction of the alcohol with chlorodiethyl phosphite and triethylamine. The phosphite then undergoes nucleophihc substitution reaction with anhydrous H2O2 forming the hydroperoxide Id (enantiomeric ratio S/R 65/35) and isomeric hydroperoxide le in a 2 1 mixture in 74% overall yield starting from the alcohol. Purification was possible by normal-phase HPLC. So in this case transformation of the phosphite to the hydroperoxide proceeds with partially retained configuration. 

Una alcohol is isomeric with aldehyde and with etbylenic oxide —... 

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