1,4-butanediol, reaction + diisocyanate

While activation energies have been published for many isocyanate/ alcohol reactions, relatively few reports have been made of the heat of reaction. Bayer [136] reported a heat of reaction of 52 kcal mole , or 26 kcal equiv", for the hexamethylene diisocyanate/1,4-butanediol reaction. Lovering and Laidler [137] measured heats of reactions for the butyl alcohol isomers with several aromatic isocyanates. Values ranged from 18.5 to 25 kcal equiv . ... 

Heat of reaction is reported to be -52 kcal/mole in the case of the hexamethylene diisocyanate and 1,4-butanediol reaction.1 The same diisocyanate, reacting with poly(ethylene adipate) glycol at 100°C was found to show a reaction velocity constant, k, of 0.00083 1 mol 1 sec 1, with an activation energy, E, of 11.0 kcal/mole.2 4 At the same temperature diphenylmeth-ane-4,41-diisocyanate (MDI) reportedly reacted with poly (diethylene adipate) glycol in mono-chlorobenzene with k = 0.00091 1 mole 1 sec 1, and E = 10.5 kcal/mole.3 4... 

Heating butanediol with acetylene in the presence of an acidic mercuric salt gives the cycHc acetal expected from butanediol and acetaldehyde (128). A commercially important reaction is with diisocyanates to form polyurethanes (129) (see Urethane POLYMERS). 

The segments derived from the condensation reaction of the butanediol and the diisocyanate agglomerate into separate phases, which are hard and crystalline. The elastomeric chains are thus cross-linked to form a network similar in many ways to that given by the simple... 

Many diols and polyols like 1, 4-butanediol and hydroxy-terminated polyesters or polyethers or polyesteramides are used for reaction with diisocyanates commercially. 

Polyurethanes (PUs) are produced by the reaction of a diisocyanate and a diol or higher polyol. As in the case of nylons and polyesters, the aliphatic PUs and those with many methylene groups between functional groups can be more flexible than aromatic PUs. A typical polyurethane is synthesized using the reactants 1,4-butanediol and hexamethylene diisocyanate as shown below ... 

Hard Segments. The hard segments are the linear reaction products of the diisocyanate component and the third monomer type in the TPU elastomer recipe, the small glycol-chain-extender component. In Figure 5 we see a typical TPU hard-segment structure which is formed from MDI and 1,4-BDO (1,4-butanediol). 

Polymers of this nature can be polymerized either in solution or in bulk in the latter case they are normally reacted at high temperatures, e.g., 100-150 C. Since our goal was a casting resin, the formulations were reacted in bulk and at lower temperatures to protect heat sensitive electronic components furthermore, low reaction temperatures minimize side reactions that can lead to crosslinking and polymer insolubility. In this process the polyols and diisocyanates were mixed and allowed to react for about 25 minutes at 71 C to form the prepolymer formation while longer times resulted in material too viscous to cast or deaerate. After the indicated time, 1,4-butanediol was added followed by deaeration and subsequent encapsulation of a preheated (71 C) electronic device. A second deaeration of the encapsulated part is usually necessary. Pot life for such a system is about 15 minutes. Final reaction or "cure" was 24 hours at 71 C. 

Poly(butylene succinate) belongs to the poly(alkylene dicarboxylate) family that can be obtained by polycondensation of a,o>-diols such as ethylene glycol and 1,4-butanediol, with aliphatic dicarboxylic acids, such as succinic and adipic acid. PBS is commonly prepared via esterification of succinic acid and BDO or transesterification of dimethyl succinate and BDO to oligomers followed by a subsequent polycondensation reaction, removing excess BDO. Catalysts include SnCh [81], p-toluenesulfonic acid [82], tetrabutyltitanate [83] and lanthanide triflates [84]. To produce PBS with sufficiently high molar mass often chain-extenders are used. Examples are the use of diisocyanates [83,85-87], bisoxazoline [88] and biscaprolactamates [89]. 

To produce a terephtalate adipate copolyester, dimethyl terephthalate, adipic acid, 1,4-butanediol, and glycerol are mixed together with tetrabutyl orthotitanate as a catalyst (44). The reaction mixture is then heated to a temperature of 180°C for 6 h and at 240°C. The excess dihydroxy compound can be removed by distillation in vacuo. Then hexamethylene diisocyanate is slowly added to the mixture. The diisocyanate act as chain extenders. From this material, a biodegradable polyester film can be produced. In addition, the s mtheses of related copolyesters have been described in detail (45). It has been found that the addition of chalk can achieve an additional improvement in the biodegradability. 

A polycarbonate TPE polyurethane that claims biostability is achieved through its replacement of virtually all ether or ester linkages with carbonate groups. The soft segment is composed of a polycarbonate diol formed by the condensation reaction of 1,6-hexanediol with ethylene carbonate. The polycarbonate diol is converted to a high molecular weight polyurethane by the reaction with 1,4-methylene bisphenyl diisocyanate (MDI) and 1,4-butanediol. It is reported to be resistant to environmental stress cracking as experienced with insulation on pacemaker lead wires. The polymer can be extruded, injection molded or compression-molded, and can be bonded with conventional urethane adhesives and solvents (Tables 4.4, 4.12, 4.13, and 4.14). 

To produce the millable polyurethane elastomers, one can bring diisocyanate molecules into reaction with oligomeric hydroxyl-terminated polyesters or polyethers and lower-molecular-weight diols (e.g., 1,4-butanediol). The ester-derived elastomers are designated AU, while the ether-derived materials are designated EU. An illustrative chemical structure is given here, where toluene diisocyanate was used ... 

Butylene glycol n. (1,4-butanediol, tetra-methylene glycol). A stable, hygroscopic, colorless liquid used in the production of polyesters by reaction with dibasic acids, and in the production of polyurethanes by reaction with diisocyanates See image). 

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