1- Butene boiling point

To a solution of 130 parts cvclopropvl-di-(4-fluorophenyl)-carbinol in 240 parts benzene are added dropwise 43 parts thionyl-chloride. The whole is refluxed until no more gas is evolved. The reaction mixture is then evaporated. The residue is distilled in vacuo, yielding 4-chloro-1,1-di-(4-fluorophenyl)-1-butene, boiling point 165°C to 167°C at 6 mm pressure oq 1.5698 d2o 1.2151. 

A solution of 61 parts 4-chloro-l,l-di-(4-fluorophenyl)-l-butene in 400 parts 2-propanol is hydrogenated at normal pressure and at room temperature in the presence of 5.5 parts palladium-on-charcoal catalyst 10% (exothermic reaction, temperature rises to about 30°C). After the calculated amount of hydrogen is taken up, hydrogenation is stopped. The catalyst is filered off and the filtrate is evaporated. The oily residue is distilled in vacuo, yielding l-chloro-4,4-di-(4-fluorophenyl)-butane, boiling point 166° to 168°C at 6 mm pressure ... 

The industrial reactions involving cis- and trans-2-butene are the same and produce the same products. There are also addition reactions where both 1-butene and 2-butene give the same product. For this reason, it is economically feasible to isomerize 1-butene to 2-butene (cis and trans) and then separate the mixture. The isomerization reaction yields two streams, one of 2-butene and the other of isobutene, which are separated by fractional distillation, each with a purity of 80-90%. Table 2-3 shows the boiling points of the different butene isomers. 

Methyl ethyl ketone MEK (2-butanone) is a colorless liquid similar to acetone, but its boiling point is higher (79.5°C). The production of MEK from n-butenes is a liquid-phase oxidation process similar to that used to... 

Dinitro-2-butene may be prepared from 1-chloro-l-nitro-ethane by the same procedure, in 30% yield. The compound melts at 28-28.5° and has a boiling point of 135°/11 mm. Commercially available 1-chloro-l-nitroethane contains about 10% 1,1-dichloro-l-nitro-ethane and 2-chloro-2-nitropropane which cannot be separated by distillation, but these impurities do not interfere with the preparation. Distillation of 2,3-dinitro-2-butene behind safety glass in a nitrogen atmosphere is advisable. The submitters, in preparing this compound, have had one explosion over a period of ten years. 

Phenylazide and 3-methyl-1-butene were dissolved in n-hexane and stirred for 20 days in the dark. Then, unreacted phenylazide and 3-methyl-1-butene were removed by distillation. A liquid residue with a higher boiling point was obtained. The electronic spectrum of the residue differs from both components. It gives absorption peaks at 287nm and 303nm as is shown in Figure 1. 

In Figure 6—1, if you look closely, you 11 see that the difference between butene-1 and the butene-2 is the location of the double bond. Butene-1 has it at the end position/ butene-2 at the middle. The methyl groups in trans-butene-2 are across from each other, on opposite sides of the fence in the CIS form they are next to each other or on the same side of the fence. The difference is more than cosmetic. It determines the way the molecule behaves, physically and chemically. Check the boiling points, for instance, in Figure 6—1. They differ, and that helps in the separation process. In a few paragraphs, the different applications for butylenes that derive from their chemical behavior differences will be covered. 

The boiling points of butadiene, isobutylene, and butene-1 make it impractical to recover a high purity butene-1 stream without first removing the... 

In the development of a 3,4-epoxy-l-butene (1) rearrangement process suitable for industrial scale-up, a number of factors were evident. The product (2,5-DHF) and starting material (1) are both liquids with identical boiling points (66°C). No practical method is known by which to separate these isomers. This fact demands that the catalytic process be performed at high conversion for acceptable economics. The common practice of recycling unreacted starting material was not an option for this process. 

As with alkanes, the boiling points and melting points of alkenes decrease with increasing molecular weight, but show some variations that depend on the shape of the molecule. Alkenes with the same molecular formula are isomers of one another if the position and the stereochemistry of the double bond differ. For example, there are four different acyclic structures that can be drawn for butene (C4H8). They have different b.p. and m.p. as follows. 

Butenes or butylenes are hydrocarbon alkenes that exist as four different isomers. Each isomer is a flammable gas at normal room temperature and one atmosphere pressure, but their boiling points indicate that butenes can be condensed at low ambient temperatures and/or increase pressure similar to propane and butane. The 2 designation in the names indicates the position of the double bond. The cis and trans labels indicate geometric isomerism. Geometric isomers are molecules that have similar atoms and bonds but different spatial arrangement of atoms. The structures indicate that three of the butenes are normal butenes, n-butenes, but that methylpropene is branched. Methylpropene is also called isobutene or isobutylene. Isobutenes are more reactive than n-butenes, and reaction mechanisms involving isobutenes differ from those of normal butenes. 

Most butenes are produced in the cracking process in refineries along with other C-4 fractions such as the butanes. Butenes are separated from other compounds and each other by several methods. Isobutene is separated from normal butanes by absorption in a sulfuric acid solution. Normal butenes can be separated from butanes by fractionation. The close boiling points of butanes and butenes make straight fractional distillation an inadequate separation... 

Because of their very similar boiling points and azeotrope formation, the components of the C4 fraction cannot be separated by distillation. Instead, other physical and chemical methods must be used. 1,3-Butadiene is recovered by complex formation or by extractive distillation.143-146 Since the reactivity of isobutylene is higher than that of n-butenes, it is separated next by chemical transformations. It is converted with water or methyl alcohol to form, respectively, tert-butyl alcohol and tert-butyl methyl ether, or by oligomerization and polymerization. The remaining n-butenes may be isomerized to yield additional isobutylene. Alternatively, 1-butene in the butadiene-free C4 fraction is isomerized to 2-butenes. The difference between the boiling points of 2-butenes and isobutylene is sufficient to separate them by distillation. n-Butenes and butane may also be separated by extractive distillation.147... 

Butene from 1,3-butadiene 192,193 Close-boiling-point problem... 

Butadiene (1,3-butadiene, boiling point -4.4°C, density 0.6211, flash point -85°C) is made by steam cracking and by the dehydrogenation of butane or the butenes using an iron oxide (Fe203) catalyst. 

Methyl ethyl ketone (MEK boiling point 769.6°C, density 0.8062, flash point -6°C) is an important coating solvent for many polymers and is made by the sulfation and hydration of 1 or 2-butene to sec-butyl alcohol, which is then dehydrogenated to the ketone (Fig. 1). 

Methyl tertiary butyl ether (methyl-r-butyl ether, MTBE boiling point 55°C, flash point -30°C) has excited considerable interest because it is a good octane enhancer for gasoline (it blends as if it had a research octane number of 115 to 135). It also offers a method of selectively removing isobutylene from a mixed C4 stream, thus enabling the recovery of high-purity butene-1. Furthermore, methyl tertiary butyl ether can be isolated, then cracked to yield highly pure iso-butylene and methanol. 

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