1.4- Butanediol, dehydration

Butadiene could also be obtained by the reaction of acetylene and formaldehyde in the vapor phase over a copper acetylide catalyst. The produced 1,4-butynediol is hydrogenated to 1,4-butanediol. Dehydration of 1,4-butanediol yields butadiene. 

Butanediol dehydration, 41 155 Butane-2,3-dione synthesis, 41 302-303 Butanethiol, dissociation, 37 292 -Butanol, see 1-Butanol 2-Butanol... 

Hunter SE, Ehrenberger CE, Savage PE. (2006). Kinetics and mechanism of telrahydrofuran synthesis via 1,4-butanediol dehydration in high-temperature water. JOrg Chem, 71,6229— 6239. 

Reactions with Aldehydes and Ketones. The base-catalyzed self-addition of acetaldehyde leads to formation of the dimer, acetaldol [107-89-1/, which can be hydrogenated to form 1,3-butanediol [107-88-0] or dehydrated to form crotonaldehyde [4170-30-3]. Crotonaldehyde can also be made directiy by the vapor-phase condensation of acetaldehyde over a catalyst (53). 

Rea.ctlons, The chemistry of butanediol is deterrnined by the two primary hydroxyls. Esterification is normal. It is advisable to use nonacidic catalysts for esterification and transesterification (122) to avoid cycHc dehydration. When carbonate esters are prepared at high dilutions, some cycHc ester is formed more concentrated solutions give a polymeric product (123). With excess phosgene the usefiil bischloroformate can be prepared (124). 

With various catalysts, butanediol adds carbon monoxide to form adipic acid. Heating with acidic catalysts dehydrates butanediol to tetrahydrofuran [109-99-9] C HgO (see Euran derivatives). With dehydrogenation catalysts, such as copper chromite, butanediol forms butyrolactone (133). With certain cobalt catalysts both dehydration and dehydrogenation occur, giving 2,3-dihydrofuran (134). 

Manufacturing. Almost all the THE in the United States is currendy produced by the acid-catalyzed dehydration of 1,4-butanediol [10-63-4]. Only one plant in the United States still makes THE by the hydrogenation of furfural (29). Du Pont recendy claimed a new low cost process for producing THE from / -butane that they plan to commercialize in 1995 (30—32). The new process transport-bed oxidizes / -butane to cmde maleic anhydride, then follows with a hydrogen reduction of aqueous maleic acid to THE (30). 

Butadiene is obtained mainly as a coproduct with other light olefins from steam cracking units for ethylene production. Other sources of butadiene are the catalytic dehydrogenation of butanes and butenes, and dehydration of 1,4-butanediol. Butadiene is a colorless gas with a mild aromatic odor. Its specific gravity is 0.6211 at 20°C and its boiling temperature is -4.4°C. The U.S. production of butadiene reached 4.1 billion pounds in 1997 and it was the 36th highest-volume chemical. ... 

Simple conjugated dienes used in polymer synthesis include 1,3-butadiene, chloroprene (Z-chloro-l -butadiene), and isoprene (2-methyl-l,3-butadiene). Isoprene has been prepared industrially by several methods, including the acid-catalyzed double dehydration of S-methyl-l/S-butanediol. 

Since 1,4-butanediol (BD) undergoes dehydration side reaction in the presence of acid resulting in THF formation, the hydroxy-ester interchange reaction is the preferred method for the preparation of PBT. The first stage of reaction is carried out at 150-200°C and consists of a hydroxy-ester interchange between DMT and excess butanediol with elimination of methanol. In the second stage, temperature is raised to 250°C and BD excess is eliminated under vacuum. Tetraisopropoxy-and tetrabutoxytitanium are efficient catalysts for bodi stages (Scheme 2.20). 

Table 12.3 summarizes the uses of formaldehyde. Two important thermosetting plastics, urea- and phenol-copolymers, take nearly one half the formaldehyde manufactured. Urea-formaldehyde resins are used in particleboard, phenol-formaldehyde resins in plywood. 1,4-Butanediol is made for some polyesters and is an example of acetylene chemistry that has not yet been replaced. Tetrahydrofiiran (THF) is a common solvent that is made by dehydration of 1,4-butanediol. 

Pinacol rearrangement is a dehydration of a 1,2-diol to form a ketone. 2,3-drmethyl-2,3-butanediol has the common name pinacol (a symmetrical diol). When it is treated with strong acid, e.g. H2SO4, it gives 3,3-dimethyl-2-butanone (methyl r-butyl ketone), also commonly known as pinacolone. The product results from the loss of water and molecular rearrangement. In the rearrangement of pinacol equivalent carbocations are formed no matter which hydroxyl group is protonated and leaves. 

A low-cost route to 1,4-butanediol and tetrahydrofuran based on maleic anhydride has been disclosed (Davy process).343,344 Here dimethyl or diethyl maleate is hydrogenated over a copper catalyst. Rapid saturation of the C—C double bond forms diethyl succinate, which subsequently undergoes further slower transformations (ester hydrogenolysis and reduction as well as dehydration) to yield a mixture of y-butyrolactone, 1,4-butanediol, tetrahydrofuran, and ethanol. After separation both ethanol and y-butyrolactone are recycled. 

Exercise 16-43 How could one dehydrate 2,3-dimethyl-2,3-butanediol to 2,3-di-methyl-1,3-butadiene without forming excessive amounts of 3,3-dimethyl-2-butanone in the process ... 

The higher activities of heteropoly acids are also found for the dehydration of 1,4-butanediol to give tetrahydrofuran (THF) (174). The activity order is H4SiW 2O40 > H3PW12O40 > H3PMO 2O40. Rate data are summarized by... 

A conventional preparation of 2,3-diphenyl-1,3-butadiene involves dehydration of meso-2,3-diphenyl-2,3-butanediol by acidic reagents including acetic anhydride,3-5 acetyl bromide,5 sulfanilic acid,6 and potassium hydrogen sulfate.7 Other procedures have been summarized2 previously. 

As catalytic tests four reactions, isomerization of 1-butene and methyloxirane, dehydration of 2-propanol and the pinacol rearrangement of 2,3-dimethyl-2,3-butanediol were used. 

Derivation (1) Catalytic hydrogenation of furan with nickel catalyst. (2) Acid-catalyzed dehydration of 1,4-butanediol. 

Butanediol conversion on Co-Zn/porcelain catalyst is a paralell-consecu-tive process including dehydrogenation, inter- and intramolecular dehydration as well as cyclization ind cracking reactions. The studied catalyst support pretreated with HCl activates the dehydration and cyclization reactions of 1,4-buta-nediol and 4-hydroxybutanal. These reactions result in the formation of tetrahydrofuran and 2,3-dihydrofuran, respectively. 

Added to this are side reactions of hydrogenolysis and dehydration, yielding butanol and furan. Traces of acidity may also favor the production of butanediol and hydroxy-butyraldehyde. 

This process, employed by Toyo Soda in its Shin-Nanyo complex in Japan, carries out butadiene chlorination for the joint manufacture of chloroprene, 1,4-butanediol and tetrahydrofuran by dehydration of the dioL... 

The phase separation of reactants hindered attempts to carry out lipase-catalyzed synthesis of poly(butylene succinate) (PBS) from succinic acid and 1,4-butanediol via dehydration. Therefore, in order to obtain a monophasic reaction mixture, dimethyl succinate was used in place of succinic acid. [49] The reaction mixture remained monophasic during the reaction course, and after 21 h at 95 °C PBS with M of 38000 was obtained. 

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