Green approach towards Synthesis and Structural Analysis of benzocaine-based compound and its co-crystals
Jeevan Dontulwar*, Anuja G. Kondalkar
Department of Chemistry, Mathuradas Mohota College of Science, Nagpur, Maharashtra.
*Corresponding Author E-mail: jdontulwar@yahoo.co.in
ABSTRACT:
The pharmaceutical cocrystals have sparked a lot of attention because of their ability to improve a drug’s physicochemical flaws, like poor water solubility. The amino carboxylic derivative of benzene was used to synthesized the benzocaine-based compounds which shows numerous biological activities. Here the mechanochemical solvent assisted grinding method were used to obtain the benzocaine-based co-crystals which is not reported yet before. The synthesized benzocain co-crystals were further analyzed using P-XRD and FTIR spectroscopic techniques. The shifting of IR peak from its individual compounds are clearly confirm the formation of co-crystal. From P-XRD analysis it is confirms that the benzocain compound and coformer shows different phase compare to its co-crystal which give the confirmation of co-crystal formation. The formation of co-crystals was further supported by taking their melting point which is completely different than pure component and its co-former. The Cambridge Structural Database (CSD) survey were used for structural analysis of reported benzocaine using mercury software. The crystal explorer software were used to calculate the percentage bond interactions in the reported benzocaine compound.
Because of the frequent use of first-line medications, the human body has evolved resistance to various drugs as a result of changing lifestyles. Cocrystals are a modified version of a medication with many uses. An active pharmaceutical ingredient (API), benzocaine, which is employed as an anesthetic, is produced in the laboratory in this study.3-4 Benzocaine cocrystal was generated by grinding mechanochemically with para nitro benzoic acid. To create hydrogen bonds in the co-former and API, grinding should be monotonous and continuous. Mercury-Software was used to examine the synthesized cocrystals. Mercury Software is used to anticipate and detect hydrogen bonding in the Benzocaine molecule. The research focuses on improving medication sustainability, bioavailability, solubility, tablet ability, and a variety of other aspects that will aid in better drug administration for ordinary people.5-7
Multicomponent crystals based on hydrogen bonding interactions without the transfer of hydrogen ions to produce salt are known as Co-crystals. Co-crystals are made up of two or more components that combine to form a distinct crystalline structure with distinct properties.8,9 Because of its capacity to change physicochemical properties while retaining therapeutic activity, co crystal development and study has become quite popular. Two or more molecules, such as medicine and co-former, are mixed in a co crystal to produce a single-phase molecule in a predetermined proportion. The bioavailability of a medicinal molecule can be increased based on the necessity, which is a key benefit of producing a co crystal. A medicinal molecule’s solubility, dissolution, moisture uptake, and chemical stability can all be affected by co-crystallization. The solubility of a medicine is crucial to its effectiveness. Poor water solubility can cause poor dissolution, affecting bioavailability and pharmacokinetics. While adding ionizable moieties to a non-ionizable medication can improve solubility, it can also change the molecule’s expected pharmacological impact. Co-crystals improve a compound’s solid-state stability and solubility. Pharmaceutical co-crystal is a crystalline material made up of an API (Active Pharmaceutical Ingredient) and one or more distinct co crystal formers that are solid at room temperature.10,11 Co-crystals are solids that are crystalline materials made of two or more molecules in the same crystal lattice, according to the definition proposed by FDA in draught guidance.12,13 Co-crystals can also be customized to improve the process ability of APIs during drug product manufacturing, according to the FDA.14-16 Quinhydrone was the first co-crystal to be made, and it is a 1:1 co-crystal of Benzoquinone and Hydroquinone.17,18 In this study, co-crystal of local anesthetic-Benzocaine was generated by mechanochemically grinding with para Nitro Benzoic Acid. The ethyl ester of p-aminobenzoic acid is benzocaine. Fischer esterification or reduction of ethyl p-nitrobenzoate can be used to make it from PABA and ethanol.19 Benzocaine is only little soluble in water. Dilute acids make it more soluble, and ethanol, chloroform, and ethyl ether make it highly soluble. Molar mass of Benzocaine is 165.19g/mol. The melting point of benzocaine is 88–90oC18, with a boiling point of around 310°C.20 Benzocaine is often used as a bulking agent in street cocaine, particularly in the United Kingdom “Legal highs” agent.21 Benzocaine has a numbering effect similar to cocaine, but consumers prefer it because it is a safer alternative. Improved bulking and binding agent that is undetectable once mixed. The study wants to improve pharmacological activity of Benzocaine by forming cocrystal.
MATERIALS AND METHODS:
Synthesis of Benzocaine:
Benzocaine is synthesized from para amino benzoic acid (PABA). This is esterification reaction in which alcohol i.e. ethanol and PABA react to form an ester as a reaction product. Chemicals required for the synthesis are - para amino benzoic acid (1.2g), Ethanol (12ml), Conc. H2SO4 (1ml), 10% Sodium Carbonate (Na2CO3) solution. Add 1.2g of PABA and 12ml of Ethanol to R.B flask. Stir the mixture until the solid is dissolved. Add 1 ml of conc. H2SO4 slowly and allow the mixture to boil gently under reflux for 75 minutes (Note – Add porcelain pieces in R.B to avoid bumping). Then allow mixture to cool and transfer it to a beaker containing 30 ml. of distilled water. 10% of sodium carbonate solution was added until gas was no longer evolved.
Filter and dry the precipitate. Recrystallize with ethanol. Observations after the synthesis were yield of synthesized Benzocaine equal to 0.25 g and melting point of Benzocaine was found to be 92°C.
Figure 1- Synthesis scheme of Benzocaine based compounds
Cocrystal synthesis:
Cocrystals were synthesized using API and coformer. When API and coformer are grinded uniformly, hydrogen bonding is formed which is detected by characterization.
Cocrystal of Benzocaine and 4-Nitro Benzoic Acid:
Weigh about 0.041g (0.00025 moles) of Benzocaine and 0.0417g (0.00025 moles) of 4-NBA. Put both the compounds in Mortar pestle and start grinding the solids gently in uniform manner for about 30-45 mins by adding dropwise ethanol to it after regular intervals. Grinding should be uniform and ethanol should not be added in excess. Using Mercury Software, hydrogen bonding between 4-NBA and Benzocaine is predicted which may or may not form shown in the figure 2. After grinding compound yield was found to be 0.04 g and Melting point was found to be 207°C.
Figure 2- Schematic representation of expected hydrogen bonding in co-crystals
RESULTS:
Crystallographic Analysis:
The crystallographic analysis is shown below in table no. 3.1 by using Mercury-software version 3.7. To support our structure we have done the CCDC analysis and obtained the crystallographic information file (CIF) code QQQAXG0122 and which used for crystallographic analysis. The title compound Benzocaine was crystalline in Orthorhombic crystal with one molecule in asymmetric unit and four molecules in the unit cell. The space group of the molecule is observed P 21 21 21. The torsional angle between O1-C8-O2-C7-C9 and C2-C3-C4-C5-C6-C1 is 5.91o as shown in the figure-4. The unit cell volume of the given compound is 909.234 Å3. The cell parameter and other crystallographic details is shown in the table below.
Table 1: Cell parameters and crystallographic details of the compound
|
Crystal Data |
Compound code |
|
Formula |
C9 H11 N O2 |
|
Molecular mass |
165.192 |
|
a(Å) |
5.302(2) |
|
b(Å) |
8.217(1) |
|
c(Å) |
20.87(2) |
|
α (°) |
90 |
|
β (°) |
90 |
|
γ (°) |
90 |
|
Z' |
1 |
|
Z |
4 |
|
Crystal system |
Orthorhombic |
|
Density (g cm-3) |
1.218 |
|
Space Group |
|
|
Cell volume |
909.234 |
Table 2: Prominent hydrogen bonding interactions present in the compound
|
D-X···A |
D-X(Å) |
X···A(Å) |
D···A(Å) |
<D-X···A(o) |
|
N1-H1…O1 |
0.862 |
2.023 |
2.893 |
177.12 |
|
N2-H2…O4 |
0.876 |
2.058 |
2.922 |
167.91 |
In the crystal structure, the strong hydrogen bonds are formed and responsible for the well packing. The N1-H11…O2 (2.236Å, 172.03o) hydrogen bond form strong in the crystal. There are two intermolecular hydrogen bonding present in the compound as shown in the figure 5. The hydrogen bonding details and its analysis are listed in the table no. 2.
Figure 3- Orthorhombic crystal packing observed in Benzocaine compound
Figure 4-Dihedral angle in Benzocaine molecule
Figure 5-The Hydrogen bonds and crystal packing in title compound
Simulated powder pattern image:
The Simulated Powder X-ray pattern for the title compound was obtained from single-crystal x-ray diffraction technique and analysis using Mercury software. The plot of diffraction intensity against 2 theta for the wavelength 1.54056 is shown in figure 6. The sharp peak indicate that substance is crystalline in nature.
Figure 6- Simulated powder X-ray pattern for the title compound obtained from single- crystal x-ray diffraction technique.
Hirshfeld Surface Analysis:
Hirshfeld Surfaces were generated using Crystal Explorer 3.1 to visualize the intermolecular interaction. The mapping of dnorm permits the examination of the intermolecular interaction by using the contact distances di and de from the Hirshfeld surface to the nearest atom inside and outside, respectively. Crystal Explorer 3.1 developed the Hirshfeld surfaces and two-dimensional fingerprint map shown below.
Figure 7- Hirshfeld surfaces are developed on dnorm mapped over the title compound
Figure 8- Two-dimensional fingerprint plots and relative contributions of various interactions to the Hirshfeld surface of the title molecule
The red spot on the Hirshfeld surface corresponds to the strong hydrogen bonding O···H/H···O, which contributes 17.2% to the total interaction and shows a sharp spike on the surface as shown in part f) of figure 7. Further, H···H weak interactions give the largest contribution of 55.8% which is represented by a blue spot on the surface shown in e) part of figure 3.6. The percentage of other weak interactions are - C···H/H···C - 22.6%, N···H/H···N - 3.3%, C···C - 1.1% as shown in d), c), b) part of figure 8.
FT-IR Pattern for Benzocaine and 4- NBA:
In figure 9 we have a primary amine which is attached to Benzene ring. So in IR spectra, there is a doublet at 3340 and 3221.26 cm-1 region, which is corresponding to N-H stretch of primary amine. At 2984.01 cm-1 there is a shoulder band which is an overtone of N-H bend vibration. At 1678 cm-1 there is a aryl ester C=O carbonyl stretch. At 1593 cm-1 region there is a broad signal of primary amine N-H bond. Around 1633 cm-1region there is C=C stretching vibration. At 769 cm-1 there is a single signal which corresponds to para substituted benzene. C-N stretch appears around 1238 cm-1 region. C-O stretch band of ester gives two or more bands. One is stronger and broad than other band which occurs in range of 1170.84 cm-1 and 1109.12 cm-1 respectively. In figure 10 at 1682 cm-1 there is aryl ester C=O carbonyl stretch. At 1309 cm-1 there is C-O stretching aromatic ester. At 1124 cm-1 there is strong C-O stretching.
Figure 9- FT-IR Pattern for Benzocaine
Figure 10- FT-IR Pattern for cocrystal of Benzocaine and 4-NBA (S1NBA)
Powder XRD Analysis:
PXRD is the fingerprint technique for assessing solid forms. The Benzocaine (S1) and Cocrystal of Benzocaine and NBA(S1NBA) diffractogram displayed recognizable intense diffraction peaks at different 2 theta values demonstrating the crystalline nature. Different levels of crystallinity were visible in the cocrystals. The cocrystal’s PXRD pattern differed from that of the parent molecule, and several additional diffraction peaks that weren’t present in the medication also showed up. Therefore, the development of a new crystalline phase is indicated by the appearance of new diffraction peaks. PXRD pattern-based cocrystal formation is well-established. To confirm the development of new cocrystals, the PXRD of the cocrystal was compared to that of the pure drug (figure 11 and figure 12).
Figure 11-The Powder X-ray pattern of Benzocaine
Figure 12-The Powder X-ray pattern of Benzocaine co-crystal
CONCLUSION:
The benzocaine based compound and its co-crystals were synthesis successfully. The melting point of the synthesized compounds was determined to be 92oC. The supramolecular study of surface analysis of pharmacologically active benzocaine compound was analyzed using mercury software. It was observed that the title compound has orthorhombic system in the crystal packing and its density is 1.218g/cm3. The peak observed in powder X-ray pattern clearly shows that the compound is highly crystalline in nature. The formation of co-crystals also easily identified using peak pattern differences in powder-X ray and FTIR techniques. The torsional angle is defined by the angle between the planes formed by atoms O1-C8-O2-C7-C9 and C2-C3-C4-C5-C6-C1 which was found to be 5.91o by using Mercury Software. Further Hirshfeld surface analysis shows that there is strong hydrogen bonding in O···H/H···O which contributes 17.2%.
CONFLICT OF INTEREST:
The authors have no conflicts of interest regarding this investigation.
ACKNOWLEDGMENT:
The Authors are thankful to Shri Mathuradas Mohota College of Science for providing lab facility. JD thanks to Department of Chemistry, Mohota College of Science to allow to do research work in the laboratory.
REFERENCES:
1. A.V.S. Ksheera Bhavani, A. Lakshmi Usha, Kayala Ashritha, E. Radha Rani. Review on Pharmaceutical Co-Crystals and Design Strategies. Asian Journal of Pharmacy and Technology. 2021; 11(2):175-0.
2. Warid Khayata, Duaa AL Zakri. Two Simple Spectrophotometric Methods for the Simultaneous Determination of Benzocaine and Phenazone. Research J. Pharm. and Tech 2018; 11(6): 2507-2511.
3. Swapnil R. Lahamage, Avinash B. Darekar, Ravindra B. Saudagar. Pharmaceutical Co-Crystallization. Asian J. Res. Pharm. Sci. 6(1): Jan.-Mar., 2016; Page 51-58.
4. Chameli S. Daingade, Bhavna U. Jain, Manish Kondawar. Pharmaceutical Co-Crystalization: A Review. Res. J. Pharma. Dosage Forms and Tech.2019; 11(2):143-146.
5. Sevukarajan M, Thanuja Bachala, Riyaz Sodanapalli, Rahul Nair. Co-Crystals: An Emerging Trend in Pharmaceutical Industry. Research J. Pharm. and Tech. 4(6): June 2011; Page 891-902.
6. Ramu Samineni, Jithendra Chimakurthy, Sumalatha. K, Dharani G, Rachana J, Manasa K, Anitha P. Co-Crystals: A Review of Recent Trends in Co Crystallization of BCS Class II Drugs. Research J. Pharm. and Tech. 2019; 12(7):3117-3124.
7. Vikram R. Shinde, Yogesh V. Pore, J. Venkateshwara Rao. A Novel Co-crystallization Technique to enhance the Physicochemical property of BCS Class-II drugs using Efavirenz as a model drug. Research Journal of Pharmacy and Technology. 2022; 15(4):1603-9.
8. Stahly, G. P. Diversity in Single- and Multiple-Component Crystals. The Search for and Prevalence of Polymorphs and Cocrystals. Crystal Growth & Design. 2007; 7 (6): 1007–1026.
9. Chetan Hasmukh Mehta, Poojary Pooja Srinivas, Anusha SB, Kirollos Bahaa Fathy Mahany, KB Koteshwara, Usha Yogendra Nayak. Computational and Experimental Insights in Design and Development of Aceclofenac Co-Crystals. Research Journal of Pharmacy and Technology. 2022; 15(8):3709-6.
10. A. V. Yadav, A. S. Shete, A. P. Dabke, P. V. Kulkarni, and S. S. Sakhar, CoCrystals: A Novel Approach to Modify Physicochemical Properties of Active Pharmaceutical Ingredients, Indian J Pharm
11. Jino Elsa Thomas, Usha Y Nayak, Jagadish PC, Koteshwara KB. Design and Characterization of Valsartan Co-Crystals to Improve its Aqueous Solubility and Dissolution Behavior. Research J. Pharm. and Tech. 2017; 10(1): 26-30.
12. Madhuri Gaddam, Nagaraju Ravouru. A Crystal Engineering design to enhance the Solubility, Dissolution, Stability and Micromeritic properties of Omeprazole via Co-crystallization Techniques. Research J. Pharm. and Tech. 2021; 14(1):356-362.
13. Polymorphs, Salts, and Cocrystals: What’s in a Name?, American Chemical Society. Cryst. Growth Des. 2012, 12, 2147−2152.
14. Bairagi, Keshab M., et al. Interplay of Halogen and Hydrogen Bonding through Co–Crystallization in Pharmacologically Active Dihydropyrimidines: Insights from Crystal Structure and Energy Framework. Chem Plus Chem. 2021; 86 (8): 1167-1176.
15. Bairagi, Keshab M., et al. Crystal structure of a 1: 1 cocrystal of nicotinamide with 2-chloro-5-nitrobenzoic acid. Acta Crystallographica Section E: Crystallographic Communications. 2019; 75(11): 1712-1718.
16. S. S. Buddhadev, K. C. Garala, Proceedings - Pharmaceutical Cocrystals—A Review. Published: 8 March 2021.
17. Brittain, H.G. Cocrystal systems of pharmaceutical interest: 2010. Cryst. Growth Des. 2011, 12, 1046–1054.
18. Jones, W.; Motherwell, W.S.; Trask, A.V. Pharmaceutical cocrystals: An emerging approach to physical property enhancement. MRS Bull. 2006, 31, 875–879.
19. Demare, Patricia; Regla, Ignacio. Synthesis of Two Local Anesthetics from Toluene: An Organic Multistep Synthesis in a Project-Oriented Laboratory Course. Journal of Chemical Education. 2012; 89 (1): 147.
20. Monographs: Pharmaceutical substances: Benzocainum – Benzocaine. The International Pharmacopoeia. Retrieved September 29, 2009.
21. D’Ans-Lax, Taschenbuch für Chemiker und Physiker, Auflage, Band , Springer Verlag 1982, ISBN 3-540-12263-X.
22. Paczkowska, Magdalena, et al. The analysis of the physicochemical properties of benzocaine polymorphs. Molecules 23.7 (2018): 1737.
Received on 03.11.2022 Modified on 17.12.2022
Accepted on 11.01.2023 ©AJRC All right reserved
Asian J. Research Chem. 2023; 16(2):169-174.
DOI: 10.52711/0974-4150.2023.00028