Abstract
It is established that dehydration of 2,3- dimethylbutane -2,3-diol passes two successive stages. During the first stage, the atom of hydrogen H (11) (state DO) approaches the atom of oxygen O (7) of hydroxogroup with the formation of a tense four-member cycle C (1) H (11) O (7) C (2) (transition state TS1), destruction of which leads to the formation of enol EO and a water molecule (state EO + H 2 O). At the second stage, in the molecule of enol EO the hydrogen atom H (20) approaches the oxygen atom O (8) of another hydroxogroup with the formation of the tense four-member cycle C (6) H (20) O (8) S (3) (transition state TS2), destruction of which leads to the detachment of the second water molecule and the formation of diene DE (state DE+2H 2 O). The difference between the energies of the formation of molecular structures of enol EO and 2,3- dimethylbuta -1,3-diene DE is positive that indicates the endothermicity of reaction. At the same time, the energy barriers of both stages are proportionate (65.6 and 61.8 kcal/mol, respectively), and the value of the released energy is about 54 kcal/mol, which corresponds to the heat of the water molecule formation. Moreover, the formation of the transition state for these reactions is displaced towards the formation of products and is of late nature. This indicates that the destruction of the bond C-H and formation of the bond O-H (transition of the hydrogen atom of the methyl group to the oxygen atom of hydroxogroup) passes faster than destruction of the bond O-C of enol whith simultaneous formation of the bond C=C 2,3-dimethylbuta-1,3-diene. Reaction of dehydration of hexahydrate 2,3-dimettylbutan-2,3-diol (DO) passes in the presence of the water molecule, the oxygen atom of which acts as an element of the transmission of hydrogen atom of the methyl group DO to the oxygen atom of the hydroxyl DO, resulting in significantly reduced energy barriers of the stages of dehydration reaction of hydrated 2,3-dimethylbutan-2,3-diol in comparison with anhydrous.
Highlights
Встановлено, що дегідратація 2,3 диметилбутан 2,3-діолу (ДО) проходить за двома послідовними стадіями: за першою в результаті відщеплення однієї молекули води утворюється проміжний продукт – 2,3 диметилбут 3 ен 2 ол, а за другою – при відщепленні ще однієї молекули води отримують 2,3 диметилбута 1,3 дієн (ДМБ)
The alkilcyclohexen derivatives, which can by widely used in chemical, perfume and food industries are received as a result of cyclization of this diene with alkylacroleins and alkylacrylics
The 2,3-dimethylbutane-2,3-diol dehydration is conducted through two consecutive stages
Summary
2,3‐Dymetylbuta-1,3-diene is the starting reagent and valuable monomer in organic synthesis used for the plastics producing, including metyl-rubbers. 6/6 ( 66 ) 2013 the catalytic dehydration of 2,3-dimethylbutane-2,3-diol is considered to be the one, to which the major attention is paid. Available acetone is consid- ered to be the original stuff in this process, which turns into 2,3-dymetylbuta-2,3-diol hexahydrate by reduction. The 2,3‐dymetylbuta-2,3-diol hexahydrate is dehydrates by azeotropic rectification with benzene [4]. Creating of the enol EO and water molecule (state EO+H2O). In the enol EO molecule, the hydrogen atom H(20) comes to the another hydroxy group atom of oxygen O(8) creating the strained four-membered rings C(6) H(20) O(8) C(3) (transitional state TS2) destruction of which leads to the splitting of the second water molecule and diene formation (state DE+2H2O)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Eastern-European Journal of Enterprise Technologies
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
