1,3-Butanediol

4-butanediol (tetramethylene glycol, 1,4-butylene glycol melting point 20.2°C, boiling point 228°C, density 1.017, flashpoint 121°C) was first prepared in 1890 by acid hydrolysis of /V,/V,-dinitro-1,4-butanediamine. Other early preparations were by reduction of succinaldehyde or succinic esters and by saponification of the diacetate prepared from 1,4-dihalobutanes. Catalytic hydrogenation of butynediol, now the principal commercial route, was first described in 1910. 

Butanediol is manufactured by way of hydrogenation of butynediol (the Reppe process)  

An alternative route involving acetoxylation of butadiene and has come on stream, and, more recently, a route based upon hydroformylation of allyl alcohol has also been used. Another process, involving chlorination of butadiene, hydrolysis of the dichlorobutene, and hydrogenation of the resulting butenediol, has been practiced. 

A more modern process involves the use of maleic anhydride as the starting material. In the process (Fig. 1), maleic anhydride is first esterified with methanol and the ester is fed to a low-pressure vapor-phase hydrogenation system where it is converted to butanediol. 

Butanediol is specified as 99.5% minimum pure, determined by gas chromatography, solidifying at 19.6°C minimum. Moisture is 0.04% maximum, determined by Karl Fischer analysis (directly or by a toluene azeotrope). 

4-Butanediol is commercially produced by several different most prevalent process for making BDO is known as the R 

4-Butanediol is commercially produced by several different proc most prevalent process for making BDO is known as the Reppe process uses acetylene, generated from natural gas, as its primary feedstock according to the following  

Other feedstocks are also utilized for making BDO. An alternative route to BDO involves the use of propylene oxide (PO) as its primary feedstock  

In East Asia, the predominant process for making EDO is the butadiene-acetoxylation process. The lower cost of tlie primary feedstock for the process, i.e. 1,3-butadiene, allows this process to be cost effective for that region. 

More recent processes involving the oxidation of butane to a maleic anhydride intermediate, using both fixed-bed and fluidized-bed processes, have been commercialized. The maleic anhydride is subsequently hydrolyzed to maleic acid or esterified in tire presence of methanol to dimethyl maleate, which can be reduced to EDO in tire presence of hydrogen and catalyst. These processes are attractive due to tire low cost of the butane feedstock. The metliod of choice to make EDO is often dictated by the local availability of tlie desired chemical feedstock. 

3 Butanediol (BDO) is another industrially important chemical that has a long history of production from fermentation. The first published report of microbial BDO production was by Harden and Walpole (1906). Like butanol production, microbial BDO production was also driven by necessity during the world wars, especially for the manufacture of synthetic rubber (Syu, 2001). Current uses include food flavorings, solvent, antifreeze, and as an ingredient for plastic manufacturing (Syu, 2001). 

The main pathway used for the production of BDO from two pyruvate moelcules is combination of these molecules to form carbon dioxide and a-acetolactate, followed by decarboxylation of a-acetolactate to form carbon dioxide and acetoin, and then reduction of acetoin by NADH to form BDO and NAD (Juni and Heym, 1956). The reduction of acetoin is reversible (Syu, 2001). If acetoin is oxidized to form diacetyl instead of being reduced, BDO can be formed by combining two diacetyl molecules to form acetate and acetylacetoin, which is then reduced by NADH or NADPH to acetylbutanediol followed by another reduction to form acetate and BDO (Juni and Heym, 1956). The sum of these reactions forms a cycle known as the BDO cycle (Juni and Heym, 1956). 

The broth at the end of the fermentation process contains the prodnct (or mixture of products), unconverted substrate, cells and other soluble and insoluble components. To recover the desired product from the broth, a separation schane is required. The separation scheme used depends on the location of the product (intracellular or extracellular), size, solubiUty, charge and concentration of the product in the broth, the product value and purity of the product. The higher the purity of the product needed, the higher the separation cost. Different separation methods are used to recover acids, alcohols and diols from the fermentation broth, which is discussed in the next section. 

The production of 1,4-butanediol (1,4-BDO) from propylene via the carbonylation of allyl acetate is noted in Chapter 8. 1,4-Butanediol from maleic anhydride is discussed later in this chapter. An alternative route for the diol is through the acetoxylation of butadiene with acetic acid followed by hydrogenation and hydrolysis. 

The first step is the liquid phase addition of acetic acid to butadiene. The acetoxylation reaction occurs at approximately 80°C and 27 atmospheres over a Pd-Te catalyst system. The reaction favors the 1,4-addition product (l,4-diacetoxy-2-butene). Hydrogenation of diacetoxybutene at 80°C and 60 atmospheres over a Ni/Zn catalyst yields 1,4-diacetoxybu-tane. The latter compound is hydrolyzed to 1,4-butanediol and acetic acid  

Acetic acid is then recovered and recycled. Butanediol is mainly used for the production of thermoplastic polyesters. 

With acid catalysts 1,4-butanediol cyclizes to tetrahydrofuran (toxic) forms 1,4-dichloro-butane with thionyl chloride and 1,4-dibromo-butane with HBr. It forms bis(chloromethyl) ether (toxic) with formaldehyde and HCl. 

Synonyms tetramethylene glycol 1,4-butyl-ene glycol 1,4-dihydroxybutane 

Structure and functional group HO—CH2— CH=CH—CH2—OH, olefinic diol with two primary hydroxyl groups Synonyms ethylene dicarbinol dimethylol ethylene 

It is used to make agricultural chemicals and the pesticide endosulfan and as an intermediate for making vitamin B. 

2-Bntene-l,4-diol is a depressant of the Central nervous system. Inhalation toxicity is very low due to its low vapor pressure. The oral LD50 value in rats and guinea pigs is 

The worldwide market for butanediol (EDO) in 2003 was about 800,000 MT, of which more than half of the production used the Reppe process, which uses acetylene and formaldehyde as the raw materials. However, the industry is moving toward the cheaper technology of using maleic anhydride obtained from butane as the raw material [85]. Although other commercial processes are used to synthesize EDO starting from butadiene, dichlorobutene, or propylene oxide, we limit ourselves to processes where carbon-supported catalysts are used the 

The Geminox process oxidizes n-butane in air over a vanadium-phosphorous oxide catalyst in a fluid-bed reactor to maleic anhydride, which is then quenched to maleic acid by absorbing it into water. This highly acidic stream is then pumped to two high-pressure fixed-bed hydrogenation reactors containing carbon-supported catalysts to convert maleic acid to BDO. The major product of reaction, a mixture of 1,4-butanediol, tetrahydrofuran (THF), and y-butyrolactone, is then separated by fractional distillation. The yield of 

4-(acetyloxy)butyl acetate 1,4-butanediol acetic acid 

BDO and THF is typically over 90 mol% based on maleic acid. The nnmber of nonntilizable by-prodncts, such as n-butanol, n-butyric acid, methane, and propane, is small. 

Butanediol is also manufactured by oxidizing butadiene with acetic acid to form 1,4-butenediol diacetate over a Pd-Te/C catalyst. This may be hydrogenated further to 1,4-butanediol diacetate (1,4-DBA) over a Ni or Pd catalyst. 1,4-DBA is then hydrolyzed over an ion-exchange resin to obtain BDO and acetic acid. The carbon support used for manufacture of the Pd-Te catalyst requires a special pore size distribution so as to attain high activity and stability of the catalyst. The inventors describe the support as preferably having a pore volume greater than 

PBT is made by reacting 1,4-butanediol (BDO) with terephthalic acid (TPA) or dimethyl terephthalate (DMT) in the presence of a transesterification catalyst. A number of different commercial routes are used for producing the monomers, as discussed below. 

2-Propanediol as well as 1,3-butanediol (1.15.) achieve antimicrobial activity at concentrations 10% additionally both solvents increase the bio availability of microbicides of low water solubility, e.g. p-hydroxy-benzoates (8.1.11.), in the water phase. 

Boiling point/range °C (101 kPa) Solidification point °C Density g/ml (20°Q Vapour pressure hPa (20°C) Viscosity mPas (20°C) 

Auto ignition temperature °C Upper flammability limit %v/v i.air Lower flammability limit %v/v i.air Solubility 

3-butanediol is neither irritant to the skin nor to mueous membranes, and is regarded as a non-toxie substance. 

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Note. Both tetramethylene glycol (1 4-butanediol) and hexamethylene glycol (1 6 hexaiiediol) may be prepared more conveniently by copper-chromium oxide reduction (Section VI,6) or, for small quantities, by reduction with lithium aluminium hydride (see Section VI,10). 

Dichlorobutane. Place 22-5g. of redistilled 1 4-butanediol and 3 ml. of dry pyridine in a 500 ml. three necked flask fitted with a reflux condenser, mechanical stirrer and thermometer. Immerse the flask in an ice bath. Add 116 g. (71 ml.) of redistilled thionyl chloride dropwise fix>m a dropping funnel (inserted into the top of the condenser) to the vigorously stirred mixture at such a rate that the temperature remains at 5-10°. When the addition is complete, remove the ice bath, keep the mixture overnight, and then reflux for 3 hours. Cool, add ice water cautiously and extract with ether. Wash the ethereal extract successively with 10 per cent sodium bicarbonate solution and water, dry with anhydrous magnesium sulphate and distil. Collect the 1 4-dichloro-butane at 55-5-56-5°/14 mm. the yield is 35 g. The b.p. under atmospheric pressure is 154 155°. 

Dibromobutane from 1 4 butanediol). In a 500 ml. threenecked flask fltted with a stirrer, reflux condenser and dropping funnel, place 154 g. (105 ml.) of 48 per cent, hydrobromic acid. Cool the flask in an ice bath. Add slowly, with stirring, 130 g. (71 ml.) of concentrated sulphuric acid. To the resulting ice-cold solution add 30 g. of redistilled 1 4-butanediol dropwise. Leave the reaction mixture to stand for 24 hours heat for 3 hours on a steam bath. The reaction mixture separates into two layers. Separate the lower layer, wash it successively with water, 10 per cent, sodium carbonate solution and water, and then dry with anhydrous magnesium sulphate. Distil and collect the 1 4-dibromo-butane at 83-84°/12 mm. The yield is 55 g. 

Dibromobutane (from 1 4-butanediol). Use 45 g. of redistilled 1 4-butanediol, 6-84 g. of purified red phosphorus and 80 g. (26 ml.) of bromine. Heat the glycol - phosphorus mixture to 100-150° and add the bromine slowly use the apparatus of Fig. Ill, 37, 1. Continue heating at 100-150° for 1 hour after all the bromine has been introduced. Allow to cool, dilute with water, add 100 ml. of ether, and remove the excess of red phosphorus by filtration. Separate the ethereal solution of the dibromide, wash it successively with 10 per cent, sodium thiosulphate solution and water, then dry over anhydrous potassium carbonate. Remove the ether on a water bath and distil the residue under diminished pressure. Collect the 1 4-dibromobutane at 83-84°/12 mm. the yield 3 73 g. 

In a 500 ml. three-necked flask, equipped with a thermometer, a sealed Hershberg stirrer and a reflux condenser, place 32-5 g. of phosphoric oxide and add 115-5 g. (67-5 ml.) of 85 per cent, orthophosphoric acid (1). When the stirred mixture has cooled to room temperature, introduce 166 g. of potassium iodide and 22-5 g. of redistilled 1 4-butanediol (b.p. 228-230° or 133-135°/18 mm.). Heat the mixture with stirring at 100-120° for 4 hours. Cool the stirred mixture to room temperature and add 75 ml. of water and 125 ml. of ether. Separate the ethereal layer, decolourise it by shaking with 25 ml. of 10 per cent, sodium thiosulphate solution, wash with 100 ml. of cold, saturated sodium chloride solution, and dry with anhydrous magnesium sulphate. Remove the ether by flash distillation (Section 11,13 compare Fig. II, 13, 4) on a steam bath and distil the residue from a Claisen flask with fractionating side arm under diminished pressure. Collect the 1 4-diiodobutane at 110°/6 mm. the yield is 65 g. 

Poly(butylene Terephthalate). Poly(butylene terephthalate) is prepared in a condensation reaction between dimethyl terephthalate and 1,4-butanediol and its repeating unit has the general structure... 

An early attempt to hydroformylate butenediol using a cobalt carbonyl catalyst gave tetrahydro-2-furanmethanol (95), presumably by aHybc rearrangement to 3-butene-l,2-diol before hydroformylation. Later, hydroformylation of butenediol diacetate with a rhodium complex as catalyst gave the acetate of 3-formyl-3-buten-l-ol (96). Hydrogenation in such a system gave 2-methyl-1,4-butanediol (97). 

Other processes explored, but not commercialized, include the direct nitric acid oxidation of cyclohexane to adipic acid (140—143), carbonylation of 1,4-butanediol [110-63-4] (144), and oxidation of cyclohexane with ozone [10028-15-5] (145—148) or hydrogen peroxide [7722-84-1] (149—150). Production of adipic acid as a by-product of biological reactions has been explored in recent years (151—156). 

Butanediol. 1,4-Butanediol [110-63-4] made from formaldehyde and acetylene, is a significant market for formaldehyde representing 11% of its demand (115). It is used to produce tetrahydrofuran (THF), which is used for polyurethane elastomers y-butyrolactone, which is used to make various pyrroHdinone derivatives poly(butylene terephthalate) (PBT), which is an engineering plastic and polyurethanes. Formaldehyde growth in the acetylenic chemicals market is threatened by alternative processes to produce 1,4-butanediol not requiring formaldehyde as a raw material (140) (see Acetylene-derived chemicals). 

The principal chemical markets for acetylene at present are its uses in the preparation of vinyl chloride, vinyl acetate, and 1,4-butanediol. Polymers from these monomers reach the consumer in the form of surface coatings (paints, films, sheets, or textiles), containers, pipe, electrical wire insulation, adhesives, and many other products which total biUions of kg. The acetylene routes to these monomers were once dominant but have been largely displaced by newer processes based on olefinic starting materials. 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

United States. The demand for acetylene generally peaked between 1965 and 1970, then declined dramatically until the early 1980s, and has been slowly increasing at between 2 and 4% per year since. The dramatic decline was related to increased availabiHty of low cost ethylene, an alternative feedstock for many chemicals, and the recent increase is due to the modest growth of acetylenic chemicals, particularly 1,4-butanediol. 

As Figure 14 also shows, the only acetylene derivatives to sustain growth during this period were the so-called acetylenic chemicals. These include 1,4-butanediol, vinyl ethers, A/-vinyl-2-pyrroHdinone, and butanediol. Of these, 1,4-butanediol, a principal feed for tetrahydrofuran, accounts for over 90% of the acetylenic chemicals demand (38). 

The U.S. Department of Commerce estimates total production of about 163,000 t in 1990. Other estimates based on demand data indicate that it was as high as 175,000 t. With demand and supply in balance, it is estimated that in 1997 the demand will be 185,000 t. The distribution in product demand is projected to be the following 1,4-butanediol and other acetylenic chemicals (45%), vinyl chloride monomer (45%), acetylene black (5%), and industrial use (5%). 

Borden-BASE Geismar, La. BASF part. ox. natural gas 90 VCM and 1,4-butanediol... 

Growth in the use of acetylene for the production of 1,4-butanediol is projected to continue at the rate of about 5% per year. However, competition from a new technology based on maleic anhydride may impact the use of acetylene in this market. 

Apart from lactic and hydroxyacetic acids, other a- and P-hydroxy acids have been small-volume specialty products produced in a variety of methods for specialized uses. y-Butyrolactone [96 8-0] which is the monomeric inner ester of y-hydroxybutyric acid [591-81-17, is a large-volume chemical derived from 1,4-butanediol (see Acetylene-derived chemicals). 

Reduction. Heterogeneous catalytic reduction processes provide effective routes for the production of maleic anhydride derivatives such as succinic anhydride [108-30-5] (26), succinates, y-butyrolactone [96-48-0] (27), tetrahydrofuran [109-99-9] (29), and 1,4-butanediol [110-63-4] (28). The technology for production of 1,4-butanediol from maleic anhydride has been reviewed (92,93). 

Survey of the patent Hterature reveals companies with processes for 1,4-butanediol from maleic anhydride include BASF (94), British Petroleum (95,96), Davy McKee (93,97), Hoechst (98), Huels (99), and Tonen (100,101). Processes for the production of y-butyrolactone have been described for operation in both the gas (102—104) and Hquid (105—108) phases. In the gas phase, direct hydrogenation of maleic anhydride in hydrogen at 245°C and 1.03 MPa gives an 88% yield of y-butyrolactone (104). Du Pont has developed a process for the production of tetrahydrofuran back-integrated to a butane feedstock (109). Slurry reactor catalysts containing palladium and rhenium are used to hydrogenate aqueous maleic acid to tetrahydrofuran (110,111). 

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