Hydrotalcite-based Materials: Synthesis, Characterization and Application

This chapter deals with the history of hydrotalcite and hydrotalcite-based materials. A rare mineral known as hydrotalcite was found in Sweden sometimes in the 1840s. Magnesium aluminum hydroxycarbonate, Mg6Al2 (OH)16CO34H2O, is its chemical name, and Taylor and Allmann independently determined its layered structure. For a long time, hydrotalcite and other isomorphous minerals (such as piroaurite, sjogrenite, and takovite) were the focus of most mineralogical studies. However, beginning in the 1970s, it was discovered that these rare minerals, also known as anionic clays, could be prepared quickly and affordably in a laboratory and have a variety of intriguing chemical properties. The different arrangements of the stacking of the layers, the ordering of the metal cations, as well as the arrangement of anions and water molecules in the interlayer galleries, result in a variety of stoichiometry in hydrotalcite, which are layered double hydroxides. Due to their unique characteristics, including their enormous surface area, ion exchangeability, insolubility in water, and most organic sorbents, among others, the compounds of the hydrotalcite group demonstrate a wide variety of potential uses.

Hydrotalcite (HT) has the chemical formula Mg6Al2 (OH)16CO3 •4H2O, with a stacked crystal structure comprising layers of positively charged hydroxides that are interlayer anion neutralization as carbonate and contain H2O particles. These double hydroxides in layers (LDH) are a class of highly fascinating materials for the industry due to the simplicity of their production and the ability to add additional layer cations and interlayer anions. Hydrotalcite-based materials such as magnesium aluminide (MgAl) hydrotalcite with a range of magnesium to aluminium (Mg/Al) molar ratios are used to prepare catalysts for effective changes of organic molecules. X-ray diffraction and scanning electron microscopy (SEM) characterization measure the catalyst's crystallinity, surface area, and shape. The HT has been employed as a scaffold for immobilizing numerous metals, enabling highly selective organic reactions, i.e., the dehydrogenation of alcohols and the deoxygenation of epoxides. It may also work with other metal catalysts to speed up subsequent responses in a single pot. It offers a vital method for the environmentally responsible synthesis of valuable compounds. This chapter overviews the hydrotalcite synthesis, classification, and application research.

Hydrotalcites (HDTL) are layered double hydroxides of the anionic clay family. They possess a large surface area, ability to accommodate divalent and trivalent metallic ions, anion exchange capacity and intercalation ability. HDTL play a vital role in nanotechnology, specifically in various nanomaterial production, functionalization, and applications. HDTL nanohybrids with unique properties are created through intercalation with various compounds like inorganic anions, organic anions, biomolecules, active pharmaceutical ingredients, and dyes. Their adaptive layered charge density and chemical combination constitute HDTL as resourceful materials befitting for a broad spectrum of applications. There are a variety of methods for preparing HDTL based nanomaterials, including co-precipitation, sol gel method, ion exchange method, intercalation method and microwave assisted methods. The morphologies of HDTL materials are characterised using technologies like X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry coupled (TGA) with Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The nanocomposites of HDTL are widely used in the field of fine chemical synthesis, pharmaceutical field, water purification, and agriculture. Biocompatible HDTL nanostructures enticed remarkable attention in therapeutic and diagnostic functions. HDTL nanohybrids are prominent bio reservoirs for drug and delivery systems and used in cancer therapy. These materials have been utilised by bioimaging techniques such as MRI and CT. The HDTL-based nanomaterials are effective adsorbents and find widespread application in the water treatment industry. These are used for the amelioration of polluted water by removing heavy metals, dyes, and other impurities. These materials are also used as flame retardants, in porous ceramics, carbon dioxide adsorption and deodorants. This chapter describes in detail about the preparation methods, properties, structural characterisation, and wide applications of HDTL based nanohybrids.

This book chapter focuses on the use of hydrotalcite-based materials in nanotechnology. Hydrotalcites are layered double hydroxides with unique structures and properties that make them attractive for various applications in nanotechnology. The chapter provides an overview of the synthesis, characterization, and applications of hydrotalcite-based materials in various fields of nanotechnology, including catalysis, drug delivery, sensing, and environmental remediation. The chapter also discusses the potential challenges and future directions in the field of hydrotalcite-based nanotechnology. Overall, this chapter highlights the importance of hydrotalcite-based materials as promising candidates for developing advanced nanotechnological applications.

Hydrotalcite is a layered double hydroxide (LDH) with a wide range of applications in catalysis, flame retardancy, PVC stabilization, fillers and reinforcements, additives in coatings and paints, pharmaceuticals and personal care, environmental remediation, and other industrial applications. This paper provides an overview of the properties and characteristics of hydrotalcite, as well as its potential applications in various industries.

The paper begins with an introduction to hydrotalcite, including its definition, structure, synthesis methods, and properties. The next section discusses the role of hydrotalcite as a catalyst, as well as its applications in the petrochemical industry and environmental remediation. The following section focuses on the flame retardant and smoke suppression properties of hydrotalcite, and its applications in plastics and polymers. The subsequent section discusses the use of hydrotalcite as a PVC stabilizer and its benefits and applications in the PVC industry.

The following sections discuss the use of hydrotalcite as a filler and reinforcement in composite materials, as an additive in coatings and paints, and in pharmaceutical and personal care formulations. The next section discusses the applications of hydrotalcite in water treatment, soil remediation, and battery and energy storage. The final section summarizes the future prospects and challenges of hydrotalcite, including emerging research areas, challenges and limitations, and potential for further industrial applications.

This paper provides a comprehensive overview of the properties and applications of hydrotalcite. It is intended to be a valuable resource for researchers, engineers, and other professionals who are interested in this versatile material.

Hydrotalcite-based materials or Hydrotalcites (HTs) have gained significant attention in recent years as efficient and versatile catalysts for various organic transformation reactions. The tunable surface properties, high surface area, and excellent thermal stability make them ideal catalysts for a range of chemical reactions. This book chapter provides an overview of the recent advances in the application of hydrotalcite-based materials as catalysts in organic transformations. The chapter highlights the various catalytic reactions where hydrotalcite-based materials have shown significant potential in the synthesis of a range of heterocycles such as chromenes, pyrans, pyrazoles, and triazoles. as well as oxidation, reduction, and C-C bond formation reactions. The chapter also discusses the various modifications that can be made to hydrotalcite-based materials to enhance their catalytic activity, selectivity, and stability by tailoring the electronic structure of the catalysts and supports. Additionally, the chapter covers the use of hydrotalcite-based materials in the synthesis of fine chemicals, pharmaceuticals, and polymers. Overall, this book chapter provides a comprehensive overview of the catalytic application of hydrotalcite-based materials in organic transformations. It will be of great interest to researchers and professionals in the fields of catalysis, organic chemistry, and materials science, as well as to those interested in developing more sustainable and efficient catalytic processes. 

Today, a promising technique for creating various biologically active organic compounds is the one-pot synthesis employing materials based on hydrotalcite. One-pot synthesis is an effective method for creating complex organic compounds because it includes the simultaneous production of many bonds and functional groups in a single reaction vessel. Layered double hydroxides (LDHs) called hydrotalcites have a special structural makeup that makes them suitable for usage as catalyst supports. The one-pot synthesis method using HT-based materials has a number of benefits, including shorter reaction times, increased product yields, and simpler reaction procedures. Utilising HT-based materials is also economical and friendly to the environment. The chapter describes a variety of one-pot methods for the creation of different heterocycles using hydrotalcites as effective catalysts.

Hydrotalcites (HTs) belong to layer double hydroxide (LDH) structure and are the anionic clays that contain a double-layered structure similar to brucite [Mg (OH)2 ]. The layering structure allows the intercalation with a variety of anionic species, oxometallates, and palmitoleates including absorbed water in the interlayer as well as on the surface. Hydrotalcites (HTs) are the high-performance solid catalysts for the one-pot synthesis of organic compounds in the industry as well as the laboratory by the various chemical transformations such as Claisen-Schmid, aldol, Knoevenagel condensations, and Michael addition, isomerization, and Friedel-Craft alkylation owing to their surface Lewis base catalyst. This chapter offers an exposition on the diverse strategies employed for crafting various organic scaffolds by using Hydrotalcites as a catalyst and their applications within the spheres of biomedical and pharmaceutical industries.

Hydrotalcites (HT) and hydrotalcite-based materials are viewed as attractive and feasible choices among heterogeneous catalysts, particularly in organic catalytic transformations. These catalysts have been widely researched as promising candidates in one-pot organic synthesis. They are synthesised via the standard co-precipitation method and can be used as support for transition metals and nanomaterials. Compared to the corrosive, hard to reutilise and, detrimental to the environment homogenous catalysts, HTs are high-functioning alternatives that deliver several benefits like profitable yields, recyclability and excellent selectivity. They are being studied today as precursors for a variety of scientific purposes such as in the production of renewable fuels, polymers, olefins and pharmaceuticals. Such processes involve essential organic reactions like isomerisation, oxidation, hydrogenation, methanation, nucleophilic additions, transesterification, and many more. In this chapter, examples of such organic reactions where hydrotalcite-based materials posed as an optimal catalyst are discussed.

The one-pot reaction has recently received a lot of attention due to its significant advantages over traditional multi-step reactions. One of the main advantages of one-pot reactions is that it can save time and resources by eliminating the need for multiple reaction steps and purification processes. It can lead to the more efficient and cost-effective synthesis of target molecules. In addition, one-pot reactions can also frequently be conducted under milder reaction conditions, such as lower temperatures and pressures, resulting in higher yields and fewer side reactions. They can also reduce the formation of hazardous waste and environmental impact. One-pot reactions also offer more opportunities for synthetic creativity, as they allow for the simultaneous manipulation of multiple functional groups in a single reaction vessel. As a result, new synthetic pathways and novel compounds might be discovered. In recent years, the combination of one-pot reactions and hydrotalcite has gained significant importance recently due to their complementary advantages. Hydrotalcite is a mineral with the chemical formula Mg6Al2 (OH)16CO3 .4H2O and is commonly found in primary and ultrabasic igneous rocks, serpentinites, and carbonate-rich sediments. It is made up of interlayer anions like carbonate or nitrate and positively charged layers of magnesium and aluminum hydroxides. The layers of magnesium and aluminum hydroxides, which are positively charged, have a large surface area and a net negative charge in hydrotalcite as a result of the interlayer anions. Its large surface area and net negative charge allow it to stabilize reactant molecules, enhancing the yield as well as the selectivity of the expected product. Additionally, altering the interlayer anions, the Mg/Al ratio, and doping with additional metal ions can further improve the catalytic activity of hydrotalcite. Compared to traditional catalysts, such as metal salts or complexes, hydrotalcite offers several advantages, including high stability, low toxicity, and easy separation from the reaction mixture. As a result, combining one-pot reactions with hydrotalcite as a catalyst can lead to more efficient and sustainable synthetic processes with greater synthetic creativity. Therefore, the aim of the book chapter is to summarize recent examples of one-pot reactions in which hydrotalcites have been used as catalysts. By exploring these examples, readers can gain insights into the potential applications of hydrotalcite as a flexible and efficient catalyst for organic reactions.