Alcohol diols, reactions

From Allyl Alcohol. The reaction of allyl alcohol [107-18-6] with chlorine and water gives a mixture of glycerol m on ochl orohydrin s consisting of 73% 3-chloropropane-l,2-diol and 27% of 2-chloropropane-l,3-diol (57). In a recycle reaction system in which allyl alcohol is fed as a 4.5—5.5 wt % solution, chlorine is added at a rate of 7—9 moles per hour. The reaction time is about five seconds, the reaction temperature 50—60°C and the recycle ratio is 10—20 1. Under these conditions m on ochl orohydrin s have been obtained in 88% yield with 9% dichlorohydrins (58) (see Allyl ALCOHOL AND DERIVATIVES). 

Sections Carbohydrates undergo chemical reactions characteristic of aldehydes and 25.17-25.24 ketones, alcohols, diols, and other classes of compounds, depending on their structure. A review of the reactions described in this chapter is presented in Table 25.2. Although some of the reactions have synthetic value, many of them are used in analysis and structure deter-mination. 

From the preceding discussion, it is easily understood that direct polyesterifications between dicarboxylic acids and aliphatic diols (Scheme 2.8, R3 = H) and polymerizations involving aliphatic or aromatic esters, acids, and alcohols (Scheme 2.8, R3 = alkyl group, and Scheme 2.9, R3 = H) are rather slow at room temperature. These reactions must be carried out in the melt at high temperature in the presence of catalysts, usually metal salts, metal oxides, or metal alkoxides. Vacuum is generally applied during the last steps of the reaction in order to eliminate the last traces of reaction by-product (water or low-molar-mass alcohol, diol, or carboxylic acid such as acetic acid) and to shift the reaction toward the... 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

Method B The chloroalkane or a,w-dichloroalkane (0.1 mol) and HC02Na (13.6 g, 0.2 mol for the chloroalkane, 27.2 g, 0.4 mol for the a,co-dichloroalkane) are stirred with TBA-Br (1.61 g, 5 mmol) until the reaction is complete (Table 3.16). H20 (10 ml) is added to the cooled mixture. The organic phase is separated, dried (MgS04), and fractionally distilled to yield the formate ester. When aqueous NaOH (50%, 4.5 ml) is added dropwise over 30 min to the vigorously stirred reaction mixture, the alcohol (diol) is formed, which can be isolated by extraction from the reaction mixture with butanone (2 x 20 ml) and fractional distillation. 

By far the most frequent reduction of esters is their conversion to alcohols. The reaction is important not only in the laboratory but also on an industrial scale where it is used mainly for hydrogenolysis of fats to fatty alcohols and glycerol. Lactones are reduced to diols. 

Amino-1 J-diols.1 This reagent can be used as an equivalent of NH3 in a synthesis of 2-amino-l,3-diols from chiral 2,3-epoxy alcohols. Thus reaction of the... 

Because of its very short lifetime, no spectroscopic observations of 1 were possible even at low temperature. However, we provided evidence for the transient formation of 1 by trapping reactions with alcohols, diols, amines,methyl iodTtle, epoxides, dienes, ketones. Some examples are as follows. 

Alkenes from diols. Reaction of v/c-diols with two secondary hydroxyls or one primary and one secondary alcohol with chlorodiphenylphosphine (2 equiv.), imidazole (4 equiv.), and iodine (2 equiv.) results in alkenes. The reaction presumably involves a vic-iododiphenylphosphinate, which can be isolated in some cases and converted to an alkene with zinc in acetic acid. 

Taddei has developed a soluble PEG supported scavenger 53 to capture a variety of nucleophilic functional groups (Scheme 13) [21]. This scavenger was based on an electrophilic dichlorotriazine core and relied on selective precipitation (by the addition of ether to acetonitrile) to remove it from the reaction mixture. This scavenger 53 is particularly versatile, and has been used to remove primary, secondary and tertiary alcohols, diols and thiols... 

Q Use your knowledge of alcohol and diol reactions to propose mechanisms and products for similar reactions that are new. 

IK Production of 2-butene-1.4-diol and propargyl alcohol by reaction between acetylene and formaldehyde in aqueous solution over a copper acetyhide catalyst supported on nickel 14, 52.99... 

Sharpless asymmetric epoxidation ° is an enantioselective epoxidation of an allylic alcohol with ferf-butyl hydroperoxide (f-BuOOH), titanium tetraisopropoxide [Ti(0-fPr)4] and (-b)- or (—)-diethyl tartrate [(-b)- or (—)-DET] to produce optically active epoxide from achiral allylic alcohol. The reaction is diastereoselective for a-substituted allylic alcohols. Formation of chiral epoxides is an important step in the synthesis of natural products because epoxides can be easily converted into diols and ethers. 

By analogy to the halolactonization reaction, the synthesis of cyclic iodocarbonates has been studied with the aim of functionalizing a double bond under regio- and stereocontrol, starting from allylic or homoallylic alcohols. These heterocyclic intermediates are employed for the synthesis of epoxy alcohols, diols and triols. 

Preparative Methods chiral titanates are usually prepared by mixing dichlorodiisopropoxytitanium and a chiral 1,4-diol in toluene. Other solvents such as ether and dichloromethane can also be employed. The alcohol exchange reaction takes place immediately at rt. Wherever necessary, liberated isopropyl alcohol is removed by azeotropic removal with toluene. The chiral 1,4-diols are prepared from dimethyl (or diethyl) tartrate by a two-step procedure comprising acetalization followed by the addition of an aryl Grignard reagent. ... 

The p-hydroxy carbonyl compound formed from the crossed aldol reaction can be reduced with NaBH4, CH3OH (Section 20.4A) to form a 1,3-diol (Reaction [1]) or dehydrated to form an a,p-unsaturated carbonyl compound (Reaction [2]). Reduction of the c(,p-unsaturated carbonyl compound forms an allylic alcohol with NaBHi (Reaction [3]), or a ketone with H2 and Pd-C (Reaction [4]) see Section 20.4C. Reaction of the a,p-unsaturated carbonyl compound with an organometalllc reagent forms two different products depending on the choice of RM (Reaction [5]) see Section 20.15. 

Acetal and ketal formation from aldehydes, resp. ketones and alcohols occurs over mordenite and other acidic zeolites [91] slightly above ambient temperatures in the liquid phase. The reaction is not confined to simple alcohols, diols can also be converted (e.g., cyclohexanone reacts with ethylglycol to 1,4, dioxaspiro(4,5)decane [2]). Note that it is likely that desorption controls the rate of such reactions as the product molecules are larger than the reactants and have, hence, a higher adsorption constant. 

Functionalized allylic systems are not only often part of target molecules but also have potential as versatile synthetic intermediates. They can frequently be used to generate multifunctional compounds by further elaboration of the C=C bond, namely by reduction (e.g. hydrogenation) or oxidation (e.g. to alcohols, diols, oxiranes, aldehydes or ketones) or by diverse addition reactions. As such reactions can very often be performed with remarkable stereocontrol by means of the allylic functionality, especially in intramolecular reactions, the potential of functionalized allylic systems is immense. 

---