Synthesis of (Ether and Amide - Hetero cycles)–Liquid Crystals and Studying of Their (Identification, Thermal Behavior, Polarized Behavior in Microscope, Other Chemical Studies)
Dr. Nagham Mahmood Aljamali1*, Dr.Sajida Hadi Ridha1, DhiaA.Hanoush2
1Chemistry Department, Faculty of Education for Women., Kufa University, Iraq.
2M.Sc. in Physical Chemistry, Thiqaar Education, Thiqaar, Iraq.
*Corresponding Author E-mail: dr.Nagham_mj@yahoo.com
ABSTRACT:
Many ether–hetero cyclic and amide –heterocycls compounds synthesized in our work by using condensation reaction,cyclization reaction,ring closure reaction,some them alkylation to form ether terminal with various starting materials and various conditions.All reactions followed by using (TLC–plate).The structures of the newly liquid crystals were characterized by using chemical techniques ((FT. IR,1H.NMR) with several studies represented by ((liquid crystal phase by using polarized optical microscope technique, DSC- Analysis, other chemicalstudies, some physical characterization, chromatographic studies)).
KEYWORDS:Liquid crystal,DSC, Schiff, ether, POM, Polarizedmicroscope, Chromatographic studies.
The history and discovery of liquid crystals (LCS)as an intermediate phase between solids and liquids is attributed to an Austrian botanist Friedrich Reinitzer. In 1888, while experimenting with certain type of cholesterol in plants,who released that it undergoes two transitions, from solid to a cloudy liquid and then to a clear liquid. Subsequently, Otto Lehmann also noted similar behavior in other substances (1-4). He coined the term liquid crystals for the first time on observing that this phase shares both the properties of liquids and solids. In 1922, Georges Friedel classified the liquid crystalline phases into nematic, semectic and cholesteric phases. But the liquid crystal research had been rather slow till 1960’s largely due to the lack of awareness of these materials among researchers and particularly about their possible practical applications (5-8).
With the advent of a discovery of switchable optical properties of liquid crystals under suitable confinements, research on liquid crystals expanded during 1970’s and 80’s looking particularly for display applications. Now, technologically, liquid crystals have become a part of our daily life right from wrist watches, calculators, etc, to laptops, high definition televisions, etc(9-13). The liquid crystals can be broadly divided into two categories: thermotropic and lyotropic liquid crystals, depending on whether the ordering is driven by temperature or concentration of liquid crystalline substance in solution, respectively (14-18).
Liquid crystals have found wide commercial application over the last (25–30)years in electro-optical flat panel display (FPD) devices for consumer audiovisual and office equipment, such as watches, clocks, stereos, calculators, portable telephones, personal organizers, notebooks, and laptop, computers. There are various other applications for liquid crystal displays (LCDs) and uses like information displays(19-22) in technical instruments and in vehicle clocks, speedometers, and navigation and positional aids. They are also applied in low-volume, niche products, like spatial light modulators and generally as very fast light shutters (23-30).
Instrumental andMaterials:
1- Melting points were recorded on Gallenkamp melting point apparatus and were uncorrected.
2- FT-IR spectra were recorded by using (FT-IR 8300 Shimadzu) in the range (400-4000) cm-1 as KBr discs.
3- 1H.NMR– Spectra were carried out with DMSO–solvent.
4- Differential Scanning Calorimeter (DSC) – Thermal Analysis.
5- Polarized Optical Microscope (POM).
6- chromatographic studies.
7- physical with analytical studies carried out in same University.
METHODOLOGY:
Synthesis of Liquid Crystals [1, 2]:
A mixture of P-hydroxy acetanilide (0.02mole) with (heptyl di bromide, or nonanyl dibromide) (0.01mole)reacted in presence of potassium carbonate in absolute ethanol as a solvent according to literatures(12,19),to yield precipitation which filtered and dried then re-crystallized to yield compound [1] and compound [2] respectively.
Synthesis of Liquid Crystals [3 - 6]:
To prepare compound [3] (0.02mole) of p-hydroxy benzoic acid reacted with heptyl dibromide(0.01mole) in ethanol according to literatures(16),precipitation which filtered and dried then re-crystallized to yield compound[3], which (0.01mole) refluxed with (0.02mole) of cystaien to give compound [4] which reacted with ethanol in presence of sulfuric acid to produce ester compound, which (0.01mole) refluxed with (0.02mole) of (p-nitro aniline, or p-aceto aniline) for (6 hrs) to produce compounds [5] and [6] respectively.
Synthesis of Liquid Crystals [7]:
(0.01mole) Of thiosemicarbazide was refluxed with carbon disulfide to yield white precipitation which filtered and dried then re-crystallized to produce 5-mrcapto-2-amino thiadiazol,according to studying(12,16,19),which refluxed with diethyl maleite to yield compound [7].
Synthesis of Liquid Crystals [8, 9]:
Compound [7] (0.01mole) was refluxed with (0.02 mole of acetyl chloride, or benzoyl chloride) according to studies(12,19),after that, gave precipitation which filtered and dried then re-crystallized to yield compound[8] and compound[9] respectively which act liquid crystals.
RESULTS AND DISCUSSION:
Our work involved, preparation of new liquid crystals [1- 9] willidentified themby spectral methods like {(FT.IR,H.NMR)andstudyingsome of physical and thermo analysis withchemical applications such as (liquid crystal - POM,thermo – Analysis -DSC,chemo- physical studies, chromatographic studies} :
Spectral Identification:
The FT.IR- Identification:
absorptionbands appeared at (1683)cm-1 due to (CO-NH) of carbonyl of amide, (NH) amide: 3381, (C-O-C) ether : 1196, (CH) aliphatic : 2976in compound [1]., while bands appeared for (CO-NH-) of carbonyl of amide: 1674 (NH) amide: 3331, (C-O-C) ether : 1139, (CH) aliphatic : 2970 incompound [2]., but compound [3] gave bandsfor (OH) of carboxylic acid :(2637- 3289),(C-O-C) ether :1107,(-CO-O) Carboxylic acid :1716.,(CH) Aliphatic : 2972., in compound [4] appeared several bands due to(C-O-C) ether : 1142, (OH) of carboxylic acid :(2630- 3255),(-CO-O) carboxylic acid :1710.,(C=N) endocycle : 1630,(C-S) endocycle : 765., other bands for (C-O-C) ether : 1174, (CO-NH) amide: 3167, (-CO) amide:1678., (C=N) endocycle : 1626, (C-S) endocycle : 758, (NO2) : 1337, 1523 due to compound [5]., while compound [6] gave many bands for (C-O-C) ether : 1154,(CO-NH) amide: 3202,(-CO) amide:1682., (C=N) endocycle :1640,(C-S) endocycle : 751, (CO- CH3)keton: 1706., compound [7] gave bands due to (CO-CH3) ketone : 1709, (CO-NH) amide: 3200,(-CO) amide:1689,(C-S) endo cycle :734, (SH) :2432, (C=N) endocycl: 1636, (CH=CH)alkene : 3106., in compound [8], noted bands due to(S-CO-CH3) ketone: 1717, (CO-NH) amide: 3215, (-CO) amide:1683,(C-S) endo cycle :767, (C=N) endocycl: 1627, (CH=CH)Alkene : 3100., the last compound [9] appeared bands due to (S-CO-Ph) ketone: 1710, (CO-NH) amide: 3230, (-CO) amide:1697,(C-S) endo cycle:745, (C=N) endocycl: 1638, (CH=CH)alkene : 3112., and other bands listed in Table (1),and some Figures (1-4)
Table (1): FT.IR- data (cm-1) of liquid Crystals [1- 9].
|
Compounds |
I.R(KBr)((Only Important Groups)) |
|
[1] |
(CO-NH-) of carbonyl of amide: 1683, (NH) Amide: 3381, (C-O-C) ether : 1196, (CH) Aliphatic : 2976 |
|
[2] |
(CO-NH-) of carbonyl of amide: 1674 (NH) Amide: 3331, (C-O-C) ether : 1139, (CH) Aliphatic : 2970 |
|
[3] |
(OH) of carboxylic acid :(2637- 3289),(C-O-C) ether :1107,(-CO-O) Carboxylic acid :1716., (CH) Aliphatic : 2972 |
|
[4] |
(C-O-C) ether : 1142, (OH) of carboxylic acid :(2630- 3255),(-CO-O) Carboxylic acid :1710.,(C=N) Endocycle : 1630, (C-S) Endocycle : 765. |
|
[5] |
(C-O-C) ether : 1174,(CO-NH) Amide: 3167,(-CO) amide:1678., (C=N) Endocycle :1626,(C-S) Endocycle : 758,(NO2) :1337,1523. |
|
[6] |
(C-O-C) ether : 1154,(CO-NH) Amide: 3202,(-CO) amide:1682., (C=N) Endocycle :1640,(C-S) Endocycle : 751, (CO- CH3)Keton: 1706. |
|
[7] |
(CO-CH3) Ketone : 1709, (CO-NH) Amide: 3200, (-CO) amide:1689,(C-S) Endo cycle :734, (SH) :2432, (C=N) Endocycl: 1636, (CH=CH)Alkene : 3106. |
|
[8] |
(S-CO-CH3) Ketone : 1717, (CO-NH) Amide: 3215, (-CO) amide:1683,(C-S) Endo cycle :767, (C=N) Endocycl: 1627, (CH=CH)Alkene : 3100. |
|
[9] |
(S-CO-Ph) Ketone : 1710, (CO-NH) Amide: 3230, (-CO) amide:1697,(C-S) Endo cycle :745, (C=N) Endocycl: 1638, (CH=CH)Alkene : 3112. |
Fig (1) :FT.IR of Liquid Crystal [1] Fig (2) :FT.IR of Liquid Crystal [2]
Fig (3) :FT.IR of Liquid Crystal [3 Fig (4) :FT.IR of Liquid Crystal [5]
The 1H.NMR- Spectra:
showed signals at {(CH3-CO-) protons : ƃ 2.90, solvent : 2.5, (NH –CO) Amide: 9.86, (-O-CH2-) Ether : (3.43-3.93), {(-CH2 -)5} Chain : (0.50- 2.20), Protons of Phenyl ring : 7.16-7.73)in compound[1]., while compound [2] appeared signals for (CH3-CO-) protons : 2.72, solvent : 2.5, (NH –CO) Amide: 9.35, {2(-O-CH2-)} Ether : (3.10-3.98), {(-CH2 -)7} Chain : (0.70- 2.32), Protons of Phenyl ring : 7.24-7.95)., but compound [3] gave signals for (OH)proton of carboxyl : 13.31 , solvent : 2.5,{2(-O-CH2-)} Ether : (3.04-3.78), {(-CH2 -)5} Chain : (0.62- 2.10), Protons of Phenyl ring : 7.10-7.84)., in compound [4] noted (OH)proton of carboxyl : 13.09 , solvent : 2.5,{2(-O-CH2-)} Ether : (3.15-3.72), {(-CH2 -)5} Chain : (0.86- 2.17), Protons of Phenyl ring : 6.87-7.90),(N-CH-CH2-S) : (3.90-4.22)., incompound [5] appeared peaks for (NH-CO)proton of amide : 9.95, solvent : 2.5,{2(-O-CH2-)} Ether : (3.00-3.79), {(-CH2 -)5} Chain : (0.71- 2.14), Protons of Phenyl ring : 6.92-7.98),(N-CH-CH2-S) : (3.84 - 4.10)., but compound [6] noted several peaks like (NH-CO)proton of amide : 9.64,solvent : 2.5,{2(-O-CH2-)} Ether : (3.12-3.75), {(-CH2 -)5} Chain : (0.86 2.11), Protons of Phenyl ring : 6.87-7.88),(N-CH-CH2-S) : (3.74 - 4.03), (CH3-CO-) : 2.36., while compound [7] appeared (CO-NH)protonamide: 9.58, (SH)Thiol :11.01, (CH=CH)Alkene : (6.07, 6.14).,other signals were appeared like (CO-NH)protonamide: 9.58, (CH=CH)Alkene : (6.00, 6.08), (CH3-CO-) : 2.31 in compound [8], and the last compound [9] appearedpeaks (CO-NH)protonamide: 9.73, (CH=CH)Alkene : (6.16, 6.24), (Ph-CO-): 2.26., and other signals in table (2), and Figures (5 - 7).
Table (2): H.NMR- data (ƃ - ppm) of Liquid Crystals [1-9]
|
Compounds |
H.NMR((Important Peaks)) |
|
[1] |
(CH3-CO-) protons : 2.90, solvent : 2.5, (NH –CO) Amide: 9.86, {2(-O-CH2-)} Ether : (3.43-3.93), (-CH2 -)5 Chain : (0.50- 2.20), Protons of Phenyl ring : 7.16-7.73) |
|
[2] |
(CH3-CO-) protons : 2.72, solvent : 2.5, (NH –CO) Amide: 9.35, {2(-O-CH2-)} Ether : (3.10-3.98), {(-CH2 -)7} Chain : (0.70- 2.32), Protons of Phenyl ring : 7.24-7.95) |
|
[3] |
(OH)proton of carboxyl : 13.31 , solvent : 2.5,{2(-O-CH2-)} Ether : (3.04-3.78), {(-CH2 -)5} Chain : (0.62- 2.10), Protons of Phenyl ring : 7.10-7.84) |
|
[4] |
(OH)proton of carboxyl : 13.09 , solvent : 2.5,{2(-O-CH2-)} Ether : (3.15-3.72), {(-CH2 -)5} Chain : (0.86- 2.17), Protons of Phenyl ring : 6.87-7.90),(N-CH-CH2-S) : (3.90-4.22). |
|
[5] |
(NH-CO)proton of amide : 9.95, solvent : 2.5,{2(-O-CH2-)} Ether : (3.00-3.79), {(-CH2 -)5} Chain : (0.71- 2.14), Protons of Phenyl ring : 6.92-7.98),(N-CH-CH2-S) : (3.84 - 4.10). |
|
[6] |
(NH-CO)proton of amide : 9.64, solvent : 2.5,{2(-O-CH2-)} Ether : (3.12-3.75), {(-CH2 -)5} Chain : (0.86 2.11), Protons of Phenyl ring : 6.87-7.88),(N-CH-CH2-S) : (3.74 - 4.03), (CH3-CO-) : 2.36. |
|
[7] |
(CO-NH)protonamide: 9.58, (SH)Thiol :11.01, (CH=CH)Alkene : (6.07, 6.14). |
|
[8] |
(CO-NH)protonamide: 9.58, (CH=CH)Alkene : (6.00, 6.08), (CH3-CO-) : 2.31. |
|
[9] |
(CO-NH)protonamide: 9.73, (CH=CH)Alkene : (6.16, 6.24),(Ph-CO-) : 2.26. |
Fig(4): H.NMR of Liquid Crystal [1]
Fig (5): H.NMR of Liquid Crystal [2]
Fig (6): H.NMR of Liquid Crystal [5]
Studyingof Liquid Crystals Behavior inOptical Microscope:
This work involvedstudying of phases ofcompounds, behavior of compounds as a liquid crystals by following with optical microscope through heating compounds with different temperatures(12).All values andresults of photos showed that thecrystal compounds [1- 9] are liquid crystals, some figures forsome compounds by optical microscope measurements are shown :
Fig (7) –Nematic Phase at (65 C) for Compound [1]
Fig (8)- Nematic Phaseat (80 C) for Compound [2]
Fig (9)– Nematic Phase at (86 C) for Compound [3]
Fig (10)– Nematic Phase at (75 C) for Compound[4]
Fig (11) – Nematic Phase at (80 C) for Compound [7]
Fig (12)–Liquid Phaseat (145 C) for Compound [8]
Fig (13)–Nematic isotropic Phase at (135 C) for Compound[9]
Thermal Studying (DSC – Measurements) :
DSC –Studies of liquid crystals [1 - 9] carried outfor supplement information about stability(12-19) of hetero cycles- amide and hetero cycles- ether liquid crystalsin some figures (14 - 16),DSC- Shapes appeared high stability toward high temperature in differential system :
Fig (14) : DSC ofLiquid Crystal [1]
Fig (15) : DSC ofLiquid Crystal [2]
Fig (16) : DSC ofLiquid Crystal [5]
Physical and Chemical Properties:
In the following, table involved many physical properties and chemical characterization act: {(Rf) ofTLC- Technique for following the chemicalreactions,type of solvent which was used in TLC – Plate, products from reactions %}, alldata are summarizedin Table (3):
Table(3): Some Physical and Chemical Properties for Compounds [1–11]
|
Compounds |
Products % |
Rf |
Solventsof(TLC) |
|
[1] |
72 |
0.64 |
Ethanol : Hexane |
|
[2] |
70 |
0.62 |
Ethanol : Hexane |
|
[3] |
72 |
0.60 |
Ethanol : Hexane |
|
[4] |
74 |
0.78 |
Ethanol : Hexane |
|
[5] |
68 |
0.70 |
Ethanol : Hexane |
|
[6] |
72 |
0.68 |
Ethanol : Hexane |
|
[7] |
76 |
0.82 |
Ethanol : Hexane |
|
[8] |
70 |
0.62 |
Ethanol : Hexane |
|
[9] |
70 |
0.76 |
Ethanol : Hexane |
Studying of Chromatography Applications(12-16) :
In this work, we supplied information about chromatography behavior for liquid crystals from data of chromatography technique which indicates that the compounds which have less polarity will filtered in first peak due to itslow polarity as compared withother compounds which have high polarity, figures (17-20) for some compounds in our work.
Fig (17): Chromatogram of Compound [1]
Fig (18): Chromatogram of Compound [2]
Fig (19): Chromatogram of Compound [3]
Fig (20): Chromatogram of Compound [4]
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Received on 23.05.2017Modified on 17.06.2017
Accepted on 20.07.2017© AJRC All right reserved
Asian J. Research Chem. 2017; 10(4):601-608.
DOI:10.5958/0974-4150.2017.00101.8