Category: Chemistry Notes PPT

Any group of organic chemical compounds is made up only of the atoms carbon (C) and hydrogen (H). The carbon atoms bind together to form the compound’s framework, and the hydrogen atoms adhere to it in a variety of ways. Petroleum and natural gas are mostly made up of hydrocarbons.

Alkanes, alkenes, and alkynes are the three main families of aliphatic hydrocarbons based on the sorts of bonds they include. Alkanes have just single bonds, whereas alkenes and alkynes have a carbon-carbon double bond and a carbon-carbon triple bond, respectively.

Now we have a basic understanding of hydrocarbons and we are ready to explore acetylene. Further in this topic, we will go through some acetylene properties and acetylene formulas.

What is Acetylene?

Acetylene is the simplest alkyne chemical molecule, with the formula C₂H₂. Acetylene is also known by the names Ethyne, Narcylen, and Vinylene. It is widely employed as a chemical component and a fuel. It is handled as a solution in its pure form, which is unstable. It is an unsaturated molecule in which the two carbon atoms are joined by a triple bond.

Acetylene Formula

As we discussed that acetylene is the first simplest alkyne. As it is an unsaturated hydrocarbon so it must have at least two carbon atoms bonded with each other to make an unsaturated hydrocarbon or we can say a triple bond. As it is the simplest alkyne so it has exactly two carbon atoms.

As we know Alkyne has a general formula as C_nH_2n-2.

So for acetylene n=2.

Hence acetylene formula =× C₂H_2×2-2=C₂H₂

As per the IUPAC Nomenclature of Organic Compounds, For alkyne, we have to add “yne” as a suffix with the prefix according to the number of carbon atoms in the molecule.

So by this rule, the IUPAC name of acetylene is “Eth(prefix for 2 carbons)+yne(suffix for alkyne)”. IUPAC name of acetylene is “Ethyne”.

Acetylene Properties

Vinylene is a colourless gas with a faint ether odour. Water, chloroform, acetone, and benzene are all easily soluble in this compound. Carbon disulfide and ethanol just marginally dissolve it. It burns easily and is lighter than air. Containers can be dramatically ruptured by prolonged exposure to heat or fire.

Acetylene cannot exist as a liquid at atmospheric pressure and has no melting point. The melting point (80.8 °C) at the minimum pressure at which liquid acetylene can exist is shown by the triple point on the phase diagram (1.27 atm). Sublimation can convert solid acetylene to vapour (gas) at temperatures below the triple point. At atmospheric pressure, the sublimation point is 84.0 °C.

Acetylene is 27.9 g per kg soluble in acetone at normal temperature. The solubility of the same amount of dimethylformamide (DMF) is 51 g. At 20.26 bar, the solubility of acetone and DMF increases to 689.0 and 628.0 g, respectively. In pressurised gas cylinders, these solvents are employed.

Acetylene C₂H₂ Structure

Use of Acetylene

Welding

Due to the high temperature of the flame, the industrial gases industry supplies around 20% of acetylene for oxyacetylene gas welding and cutting. Acetylene produces a flame of nearly 3,600 K (3,330 °C; 6,020 °F) when combined with oxygen, releasing 11.8 kJ/g. The hottest burning common fuel gas is oxyacetylene. The Oxyacetylene formula is also C₂H₂. After dicyanoacetylene’s 5,260 K (4,990 °C; 9,010 °F) and cyanogen’s 4,798 K (4,525 °C; 8,177 °F), acetylene is the third-hottest natural chemical flame. In former decades, oxy-acetylene welding was a prominent welding method. For many applications, the advancement and benefits of arc-based welding methods have rendered oxy-fuel welding obsolete. Welding using acetylene has become far less common. In regions where electricity is not widely available, oxyacetylene welding can be employed. Many metal fabrication shops employ oxyacetylene cutting.

Portable Lighting

The acetylene utilised in the lamps for portable or remote applications was generated using calcium carbide. It was used for miners and cavers before the widespread usage of incandescent lighting; or, many years later, low-power/high-lumen LED illumination; and it is currently used by mining industries in some countries where workplace safety standards do not exist. Carbide lamps were also widely employed as headlights in early automobiles and as a light source for lighthouses in the early 1900s.

Plastics and Acrylic Acid Derivatives

Acetylene can be converted to ethylene and used as a feedstock for a range of polyethene polymers. Acetylene’s conversion to acrylic acid derivatives is another important application, particularly in China. Acrylic fibres, glasses, paints, resins, and polymers are all made from these compounds.

Niche Applications

When a steel piece is too large to put into a furnace, acetylene is occasionally used to carburize (harden) it. In radiocarbon dating, acetylene is utilised to volatilize carbon. In a small specialised research furnace, carbonaceous material in an archaeological sample is treated with lithium metal to generate lithium carbide (also known as lithium acetylide). The carbide can then be treated with water to produce acetylene gas, which can be fed into a mass spectrometer to determine the carbon-14 to carbon-12 isotope ratio.

Preparation of Acetylene

This chemical has been produced by partial combustion of CH₂ since 1950. (methane). Until 1983, around 4,00,000 tonnes were produced. Friedrich Wohler discovered the reaction in 1862, and it was used to make it. The reaction of calcium carbide hydrolysis is as follows:

Ca(OH)₂ + C₂H₂→CaC₂ + 2H₂O

The foregoing reaction takes place in an electric arc furnace at a very high temperature of roughly 2000 °C.

Health Hazards Due to Acetylene

People who come into touch with this chemical may experience headaches, dizziness, and loss of consciousness. Choking death can occur if there is a significant concentration of Ethyne in the air.

The term actinides are derived from the first element of the series which is actinium. The actinide series are referred to with the symbol an. This series consists of a family of 15 elements that range between 89 and 103. The 15 elements that are part of the Actinides series are as follows: Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Californium (Cf), Einsteinium (Es), Fermium (Fm), Mendelevium (Md), Nobelium (No), and Lawrencium (Lr).

Scientists earlier in the 1940s believed that the heaviest atom is uranium. But due to constant innovation, advancements and discoveries, more and more elements were found and later added in the series. Together all the numerous elements are called Actinides.

There are few actinides that are present in nature, whereas some actinides are man-made. Five elements of Actinide that are naturally formed are plutonium, neptunium, thorium, protactinium, and uranium. Actinides were also formed during scientific experiments and discoveries.

Properties of Actinides

All the elements in the actinide series are heavy because of their large atomic mass. The elements belonging to this series have an atomic mass ranging from 227g/mol to 262g/mol. The atomic mass of hydrogen is 1 therefore; one can have a clear idea of comparatively how heavier these elements are. 

One of the most important properties of actinides is that they are radioactive in nature. The elements in this series are highly radioactive. Radioactive refers to the breaking down of the nucleus into smaller particles. The smaller particles are Alpha particles, Beta particles as well as Gamma Particles. The elements in the Actinide series release a large amount of energy on radioactive decay. The elements of Actinides are used as nuclear reactors and in nuclear weapons. There are different uses of Uranium and Thorium. Some of the elements in the actinides series are also used as smoke detectors. Actinides are typical metals and they have properties of D block and F block elements. 

There is a general configuration of Actinides which is referred to as

[Rn] 5f^1-146d^0-7 7s²

In this equation, Rn refers to the nearest noble gas which is Radium.

The f block of the modern periodic table consists of Lanthanides and Actinides.

Similarities Between Lanthanides and Actinides

(n-2)f subshell is used for filling and characterization of all the elements in the Lanthanides and Actinides. The electronic configuration of Lanthanides and Actinides are pretty much similar. Some of the major similarities between these two are listed below:

1. Lanthanides and Actinides have a prominent Oxidation State that is +3.

2. (n-2) f orbitals are involved in filling of these elements.

3. The Lanthanides and Actinides are reactive as well as electropositive.

4. As the atomic number of these elements increases, the ionic and atomic size decreases.

5. Both Lanthanides and Actinides have considerable magnetic properties.
   

Differences Between Lanthanides and Actinides

4f-orbitals are involved in the filling of Lanthanides, whereas the 5f-orbitals are involved in the filling of Actinides. The energy that binds this atom that is 4f is comparatively less than that of actinides which is 5f electrons. The shielding of the 5f electrons is also less when compared to that of 4f electrons. It is very easy to explain the paramagnetic properties of Lanthanides. On the other hand, in the case of Actinides, one cannot easily explain all the paramagnetic properties. Most of the Lanthanides are non-Radioactive except for Promethium. All the elements in the Actinide series are Radioactive in nature. There are several oxocation of the elements in the Actinides series whereas there is no oxocation in Lanthanides. The compounds that are formed by Actinides are very basic in nature as opposed to the compounds found by Lanthanides. The lanthanides and actinides are often called inner transition metals. 

Properties of Actinides

The actinides are Metals which are typical in nature. The actinides are soft, shiny, silver in color and have a good density and plasticity. Some of the actinides can also be cut with the help of a simple knife. Thorium has a similar hardness to soft steel and can be heated to roll into sheets or pull into a wire. The properties of elements in the actinide series are the same as the d-block. They can lose to multiple electrons and form a variety of ions. Actinium has a crystalline phase and is not radioactive as well as paramagnetic. The actinides are also pyrophoric, that is they ignite spontaneously when exposed to the air. 

The melting point of Actinides does not depend on the number of f electrons.  Actinides react very easily because of halogens and chalcogens. Actinides having less number of 5f electrons are used for hybridization. Actinides also have a considerable number of valence States. The actinides also react with the boiling water or with the dilute acid to form the hydrogen gas. The elements of the actinide series are ductile as well as malleable. The actinides can be combined positively with the non-metals. 

Availability of Actinide

The two actinide elements are found in abundance in earth’s crust; they are Thorium and Uranium. One can also find small quantities of Plutonium, Neptunium in Uranium. Some of the elements in the actinide series are synthetic elements. These elements are called synthetic elements, as they are not formed naturally, they are formed due to the decay of some part of a heavier element. The actinide element tarnishes when exposed to air.

Uses of Actinides

Actinides such as Americium are used in smoke detectors. Thorium is used mainly in Gas mantles. Scientists and researchers use Actinium to carry out scientific research or study. Actinium is used as a gamma source, indicator, and neutron source. A large number of actinides are used for defense operations, nuclear weapons and for the production of energy. 

Plutonium is used in nuclear reactors and for nuclear bombs as well. Many of the actinide elements are used in nuclear power plants and also for the production of electronic power. Every actinide is known for its unique atomic number and its different properties as well as characteristics. It is very important to study the chemical and physical properties of actinides to predict its reaction. The actinides do not have stable isotopes.

Conclusion

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In organic synthesis, aldol condensations are a very important class of reactions. Charles – Adolph Wurtz and Alexander Porfyrevich Borodin discovered the reaction independently in 1872. The name aldol was chosen because there is often an aldehyde and an alcohol group in the product of an aldol condensation.

Generally speaking, an aldol condensation is a nucleophile attack on a carbonyl to make a ketone or aldehyde of β-hydroxy. The nucleophile is generally an enolate of an aldehyde or ketone attacking another aldehyde or ketone molecule. An acidic or basic solution can catalyze the condensation of aldol.

By bases such as hydroxide ions and alcoxide ions, an aldehyde is partially converted to its enolate anion.

RCH₂CHO + HO- RCH=CHO- + H₂O

Aldehyde Water Enolate Water

The enolate is subjected to nucleophilic addition to the carbonyl group in a solution that contains both an aldehyde and its enolate ion. This addition is similar to the addition of reactions to aldehydes and ketones from other nucleophilic reagents.

     O

     ||

RCH₂CH

 

      O- O-O OH O

     / | || H₂O | ||

RCH₂CH RCH₂CH—RCHCH RCH₂CH—RCHCH

 

Product of Aldol Addition

The alkoxide formed in the nucleophilic addition step then abstracts a proton from the solvent (usually water or ethanol) to yield the product of aldol addition. This product is known as an aldol because it comprises a function of aldehyde and a group of hydroxyl(ald+ ol = aldol)

An important feature of aldol addition is that carbon–carbon bond formation occurs between the α-carbon atom of one aldehyde and the carbonyl group of another. This was because the generation of carbanion (enolate) can involve only proton abstraction from the α-carbon atom.

Figure 1: The reactive sites in aldol addition are the carbonyl group of one aldehyde molecule and the α-carbon atom of another.

One of these protons is removed by base to form an enolate

     O O OH O

     || || base || ||

  RCH₂CH + RCH₂CH RCH₂CH–RCHCH 

Carbonyl group to which this is the carbon–carbon that is formed in formed in the reaction

 

Aldol Addition Occurs Readily with Aldehydes:

     O

     || NaOH, H₂O

2 CH₃CH CH₃CHCH₂CHO 4 – 5°C |

                                     OH

Acetaldehyde 3-Hydroxybutanal (50%) (Acetaldol)

             O O

          || KOH, H₂O ||

2CH₃CH₂CH₂CH CH₃CH₂CH₂CHCHCH

               6 – 8°C | |

                                              OH CH₂CH₃

Butanal 2-Ethyl-3-hydroxyhexanal (75%)

The α-hydroxy aldehyde products of aldol addition undergo dehydration on heating,to yield α, β-unsaturated aldehydes:

     OH O O

      | || Heat ||

  RCH₂CHCHCH RCH₂CH=CCH + H₂O

           | 6 – 8°C | 

          R R

β -Hydroxy aldehyde α, β-unsaturated aldehydes Water

The combination of the newly formed dual bond with the carbonyl group stabilizes α, β – unsaturated aldehyde, provides the driving force for dehydration and controls the selectivity of its region. Dehydration can be done by acid or base heating the aldol. Normally, if α, β -unsaturated aldehyde is the desired product, all that is done is to carry out the base-catalyzed aldol addition reaction at elevated temperature. Under these conditions, once the aldol addition product is formed, it rapidly loses water to form α, β-unsaturated aldehyde.

                   O O

                  || NaOH, H₂O ||

  2CH₃CH₂CH₂CH CH₃CH₂CH₂CH=CCH |

                                             CH₂CH₃

Butanal 2-Ethyl-2-hexenal (86%) 

                              (Major Product)

Reactions in which two molecules of an aldehyde combine to form α, β– unsaturated aldehyde and a molec
ule of water are called aldol condensations.

To be dehydrated to alkenes, alcohols require acid catalysis. It may, therefore, seem strange that products to add aldol may be dehydrated in the base. This is another example of how increased proton acidity at α – carbon atom affects carbonyl compound reactions. Elimination may occur in a concerted E2 fashion or may be progressive and proceed through an enolate ion.

 

1. Dehydration of Aldol Products

Aldol reaction products are often subjected to subsequent water removal, consisting of a α-hydrogen group and beta – hydroxyl group. The product of this beta – elimination reaction, as shown in the following diagram, is α, β-unsaturated aldehyde or ketone. For this elimination, acid – catalyzed conditions are more commonly used (e.g. # 1, 2 & 5), but base – catalyzed elimination also occurs, particularly in heating (e.g. # 3, 4 & 5). The additional stability provided by the product’s conjugated carbonyl system makes some thermodynamically favorable ketone aldol reactions (# 4 & 5) and stereoisomer (E & Z) mixtures are obtained from reaction #4. Reaction #5 is an interesting example of a reaction of intramolecular aldol; these reactions create a new ring. 

Condensations are called reactions in which a larger molecule is formed from smaller components, eliminating a very small by-product such as water. The following examples are therefore properly referred to as condensations of aldols. In the presence of acid and base catalysts, the dehydration step of an aldol condensation is also reversible. Therefore, when heating with aqueous solutions of strong acids or bases, many α, β-unsaturated carbonyl compounds fragment into smaller aldehydes or ketones, a process known as the retro-aldehyde reaction.

 

The Acid – 

catalyzed water removal is not exceptional, as this has been noted as a common alcohol reaction. Nevertheless, it is found that the conditions required for beta-elimination are less than those used for simple alcohols. The most surprising aspect of beta-elimination, however, is that it can be base-catalyzed. 

As the equations show these eliminations could proceed from either the beta-hydroxy aldol product’s keto or enol tautomers. Although the keto tautomer route is not unreasonable (remember the increased acidity in carbonyl compounds of the α-hydrogens), the enol tautomer provides a more favourable pathway for both acid and base-catalyzed elimination of beta oxygen.

 

2. Mixed Aldol Condensations

As both the enolic donor and the electrophilic acceptor, the previous examples of aldol reactions and condensations used a common reactant. The product is always a dimer of the carbonyl reactant compound in such cases. Crossed or mixed reactions are called aldol condensations between different carbonyl reactants, and under certain conditions, such crossed aldol condensations may be effective. Some examples are shown below, and in most cases, under the conditions used, beta – elimination of water occurs. The exception, reaction # 3, is carried out under mild conditions with excess reactive aldehyde formaldehyde serving as an electrophilic acceptor. The first reaction shows that ketones with two sets of α-hydrogens can react at both sites if they are supplied with sufficient acceptor co-reactant. The interesting difference in regioselectivity in the second reaction (the reactants in the central shaded region) shows some subtle differences between the reactions of acid and base-catalyzed aldol. The base-catalyzed reaction is performed by an enolate anion donor species and the kinetically favoured removal of the proton is from the less replaced α-carbon. The acid-catalyzed aldol goes through the tautomer of the enol, and the more stable of the two tautomers of the enol is the double bond with the more replaced.Finally, there are two reactive α-carbons in reaction #4 and there may be a reversible aldol reaction in both. Only one of the two aldol products can undergo water beta-elimination, so the eventual isolated product is derived from this sequence of reaction. The Claisen-Schmidt reaction is called the aldol condensation of ketones with aryl aldehydes into α,β-unsaturated derivatives.

Two factors are responsible for the success of these mixed aldol reactions. First, aldehydes are more reactive electrophiles than ketones, and more reactive than other aldehydes is formaldehyde. Second, aldehydes that lack α-hydrogens can only function as acceptor reactants, thereby reducing by half the number of possible products.Mixed aldols in which both reactants can serve as donors and acceptors generally provide complex mixtures of dimeric (homo) aldols as well as crossed aldols. In such a case, the following abbreviated formulas illustrate the possible products, red letters representing the component of the acceptor and the donor blue.If all reactions occurred at the same rate, the same quantity would be obtained for the four products. It would be difficult to separate and purify the components of such a mixture.

 

Application of Aldol Condensation

The reaction enables carbon – carbon bonds to be formed. The reaction leads to the establishment of a C – C bond in Gluconeogenesis and Photosynthesis. This is regarded as an important reaction in metabolism biochemistry, where glycolysis is the fifth step. However, it works in the opposite way in glycolysis and serves to end the carbon – carbon bond. The reaction is commonly used to produce solvents such as alcohol isophorone and diacetone. It works as an intermediate for perfume production. It is also used in pharmaceutical manufacturing, unsaturated ketones and chalcones known as aromatic ketones. Usually, it is used to create plasticizers as well.

Aluminium hydroxide is an inorganic compound made up of aluminium ion and hydroxide ions. It is an amphoteric compound which means it can act as an acid as well as a base. Aluminium hydroxide minerals occur in nature. It holds the property of an antacid. The IUPAC name of the aluminium hydroxide is Aluminium trioxide.

Hydrophobicity is a property of aluminium hydroxide. In most cases, it produces lyophobic solutions. The hydrolysis of aluminium chloride can be used to prepare aluminium hydroxide gels.

3H₂O + AlCl₃ Al(OH)₃ + 3HCl

Aluminium Compounds

Aluminium is an inorganic element belonging to the thirteenth group. Aluminium reacts with nitrogen gas and forms an aluminium nitride

Al + N₂ → AlN

Aluminium reacts with the oxygen gas and forms aluminium trioxide also known as alumina.

Al + O₂ → Al₂O₃

Aluminium reacts with hydrochloric acid and forms aluminium trichloride as a product and hydrogen gas as a byproduct. This aluminium trichloride is used in the preparation of aluminium hydroxide gels. 

Al + HCl → AlCl₃ + H₂

Aluminium reacts with the dilute sodium hydroxide solution and forms aluminium trihydroxide. This molecule is amphoteric in nature. Therefore, it further reacts with the dilute sodium hydroxide solution and forms sodium meta illuminate aa a product and hydrogen gas as a byproduct. 

Al + NaOH (dil) → Al(OH)₃ → Na[Al(OH)₄] + H₂

Aluminium hydroxide reacts with the water molecules and forms a solution. This reaction can be used to clear drains. This reaction is also used to remove the obstructions from the drainage pipe.

AlCl₃ + H₂O → [Al (H₂O)₆]⁺³ + 3Cl⁻

Aluminium trichloride reacts with hydrochloric acid and forms white fumes.

AlCl₃ + HCl → white fumes

Structure of Aluminium Hydroxide

Aluminium cation is attracted with three hydroxide anions.

Properties of Aluminium Hydroxide

The Colour of aluminium hydroxide is white.

Its density is 2.43 g/cm³.

Its melting point is 300 degrees celsius.

Its molar mass is 78.0036.

Aluminium Hydroxide Gel Preparation

Aluminium hydroxide is hydrophobic in nature. Generally, it forms lyophobic solutions. Aluminium hydroxide gel preparation can be done with the hydrolysis of aluminium chloride.

AlCl₃ + 3H₂O → Al(OH)₃ + 3HCl

Step by Step Aluminium Hydroxide Gel Preparation

1. Prepare the 2% aluminium chloride solution (by adding 2g of aluminium chloride in 100 ml water).

2. Add 100 ml distilled water to the conical flask.

3. Boil the water with the help of the wire gauze.

4. Add 10 ml of the above prepared 2% aluminium chloride solution. Add this solution with the help of the dropper of the burette. As aluminium compounds are violent in nature.

5. Constantly stir the solution while adding aluminium chloride.

6. Heat the solution until you see a coloured solution. The colour of the aluminium hydroxide solution is white.

7. Leave the mixture for cooling at normal temperature.

8. The cooling solution is called aluminium hydroxide gel.

9. Precaution You Need to keep During Aluminium Hydroxide Gel Preparation

10. Clean the conical flask with a steaming process to avoid any kind of impurities.

11. The byproduct (Hydrochloric Acid) formed in this reaction causes destabilization of the prepared gel. therefore, needs to be removed by the dialysis process.

12. Aluminium chloride solutions need to be added in a dropwise manner.

Uses of Aluminium Hydroxide Gel

• It is used for treating gastric ulcers.

• It is used in making vaccines.

• It is used in cosmetics.

• It serves as an intermediate compound in various reactions.

• It is used as a flame retardant.

• It is used in the manufacturing of certain drugs.

Side Effects of Aluminium Hydroxide Gel

Aluminium hydroxide is generally used as a medicine. But to some people, it shows side effects when consumed. These side effects involve:

• Constipation is a possibility. Other issues, such as haemorrhoids and intestinal blockage, could result as a result of this. Contact your doctor or pharmacist right away if constipation persists or worsens.

• If your doctor has prescribed this drug, ensure that he or she has determined that the benefits are more and the side effects are negligible. The majority of people who use this medication experience no significant side effects.

• Exercise daily and drink ample amounts of water to avoid constipation. Constipation can be avoided by taking this medicine with a magnesium-containing antacid. Stool softeners may be beneficial as well. Other antacids, stool softeners, and laxatives might be discussed with your doctor or pharmacist.

• In the intestines, aluminium-containing antacids bind to phosphate, a vital physiological component. If your kidneys are normal, this can result in low phosphate levels, especially if you take big dosages for a long time.

• Get medical help right away if you experience any of the following side effects or symptoms of a serious medical problem: black/ta
  rry stools, mental/mood disorders (e.g., confusion, deep sleep), pain with urination, stomach/abdominal pain, or vomit that looks like coffee grounds. 

• This medicine seldom causes a severe allergic reaction. However, if you witness any symptoms of some allergic response, such as a rash, redness, itching/swelling (particularly of the face/tongue/throat), extreme dizziness, or shortness of breath, go to the doctor right away.

• This is a very important list of some potential adverse effects. Contact your doctor or pharmacist if you have any other side effects not listed above.

Aluminium Hydroxide: How to Use It

Before each dose, give the bottle a good shake. The flavour of the suspension may be improved by refrigerating it. Do not allow yourself to become frozen. This drug is most effective when taken without any other liquids. If necessary, dilute your dose with a little water.

This contains aluminium, which can interfere with the absorption of other medications (such as digoxin, iron, tetracycline antibiotics, pazopanib, and quinolone antibiotics like ciprofloxacin). To avoid this problem, talk to your doctor or pharmacist about how to schedule your medications.

If your acid problems persist or worsen after one week of use, or if you suspect you have a significant medical concern, seek medical help right away. 

Did You Know?

• Aluminium hydroxide reacts with both acid and base.

• Aluminium hydroxide is used in coating TiO2 nanoparticles.

• Aluminium hydroxide is used to reduce phosphate levels in people with certain kidney conditions.

• Aluminium hydroxide consumption reduces the absorption of the other medicines in the body. Therefore, two-hour gaps before and after taking aluminium hydroxide should be maintained for consuming other medicines with this.

Hence the article is very useful for the students to understand the properties, structure of aluminium hydroxide. Step by Step procedure of preparation of aluminium hydroxide gel is given in the above article.

A chemical compound is a compound which is formed from the atoms of different elements combined in a specific ratio. The various types of atoms are joined by chemical bonds. Every compound has a fixed ratio between the elements. The elements combine together so strongly that the compound behaves like one substance. 

Chemical compounds can be in the form of liquid such as water, which is made from the atoms of hydrogen and oxygen sticking together. Chemical compounds can be in the form of solid such as sodium chloride which is made from the atoms of sodium and chlorine sticking together. Some chemical compounds are dangerous to use if they are not handled with proper safety measures. There are many chemical compounds, which we use in our daily life, and today we will talk about such a chemical Compound.

Overview of Ammonium Chloride

Ammonium chloride is an inorganic chemical compound. Ammonium Chloride is a white crystalline salt that is highly soluble in water. Ammonium Chloride is composed of ammonium and chloride ions. Ammonium Chloride is a colourless chemical compound. The nature of the solutions of ammonium chloride is mildly acidic. The other names of ammonium chloride are Sal ammoniac, Salmiac, Nushadir salt, Sal Armagnac, Salt Armoniack, Salmiak.

Sal ammoniac is a natural, mineralogical form of ammonium chloride. Sal ammoniac is generally formed on burning coal dumps from the condensation of coal-derived gases. Sal ammoniac is also found around some types of volcanic vents. Sal ammoniac is majorly used as fertiliser and a flavouring agent in some types of liquor. Sal ammoniac is the product from the reaction of hydrochloric acid and ammonia.

Structure of Ammonium Chloride

The Structure of NH4Cl or Ammonium Chloride is represented as follows.

Properties of Ammonium Chloride

Let us look at the properties of Ammonium Chloride

Production of Ammonium Chloride

Ammonium Chloride is the product of the Solvay process. Apart from the Ammonium chloride, the sodium carbonate is another product of the Solvay process.

[ CO_{2} + 2 NH_{3} + 2NaCl + H_{2}O rightarrow 2NH_{4}Cl + Na_{2}CO_{3} ]

Usually, this method is used to minimise the release of ammonia from some industrial work. Commercially, ammonium chloride is prepared from the combination of ammonia (NH₃) with either hydrogen chloride (gas) or hydrochloric acid.

[ NH_{3} + HCl rightarrow NH_{4}Cl ]

Reactions with Ammonium Chloride

To release ammonia gas, ammonium chloride reacts with the strong base.

[ NH_{4}Cl + NaOH rightarrow NH_{3} + NaCl + H_{2}O ]

Ammonium chloride reacts with the alkali metal carbonates at the increased temperature which gives the ammonia and alkali metal chloride.

[ 2NH_{4}Cl + Na_{2}CO_{3} rightarrow 2NaCl + CO_{2} + H_{2}O + 2NH_{3} ]

When heated, Ammonium chloride shows a neutral nature, but in reality, ammonium chloride decomposes into ammonia, and hydrogen chloride gas on the heat.

[ NH_{4}Cl rightarrow NH_{3} + HCl ]

The solution of ammonium chloride in water has a pH in the range of 4.6 to 6.0.

History of Ammonium Chloride

The ancient mention of the ammonium chloride was in 554 A.D. in China. There were two sources of ammonium chloride at the time. The first source was the vents of underground coal fires in Central Asia, specifically, in the Tian Shan Mountains. The second source of ammonium chloride was the fumaroles of the volcano Mount Taftan in southeastern Iran. The Ammonium chloride word is derived from the Iranian phrase anosh adur which means immortal fire. Ammonium chloride was transported at that time along the Silk Road eastwards to China and westwards to the Muslim lands and Europe. The Arabs of Egypt discovered ammonium chloride in 800 A.D. from the burning camel dung, and that source became an alternative source in Central Asia.

Application of Ammonium Chloride 

Fertilisers

The main application of ammonium chloride is as a source of nitrogen in fertilisers. In Asia, in the crops of rice and wheat, Ammonium chloride is used as a fertiliser.

Metalwork

In preparing metals which are to be tin coated, galvanised or soldered, Ammonium chloride is used as a flux. Ammonium chloride works as a flux which cleans the surface of workpieces. Ammonium chloride is used as a flux in solder as well.

Medicine

Ammonium chloride is used in the field of medicine too. Ammonium chloride is used in cough medicines. Ammonium salts are useful to reduce nausea and vomiting. In the treatment of severe metabolic alkalosis, Ammonium chloride is used as a systemic acidifying agent. Ammonium chloride is useful in the oral acid loading test to diagnose distal renal tubular acidosis too.

Food

Ammonium chloride is used as a yeast nutrient in breadmaking and as an acidifier. In dark sweets called Salmiak, Ammonium chloride is used to spice up. Salmiak is a dark sweet which is popular in Nordic and other nearby countries. In baked cookies, ammonium chloride is used to bring the crisp texture. Ammonium chloride is called the Noshader in Iran, Tajikistan, India, Pakistan, and some Arab countries. In samosas and jalebi, ammonium chloride is used to improve the crispness.

In the Laboratory

To produce low temperatures in cooling baths, Ammonium chloride is used. As a buffer solution, ammonium chloride is used with ammonia. In palaeontology, the vapour of ammonium chloride is cemented on fossils; this stuff forms a white layer which can be easily removed and it is quite harmless.

Flotation

With the help of ammonium
chloride solution, Giant squid and some other large species of squid maintain the neutral buoyancy in seawater because the density of the solution of Ammonium chloride is less than the density of seawater. The solution of ammonium chloride tastes like Salmiakki, and because of this unusual taste, giant squids feel un-attracted towards the human.

Other Applications

To reduce the clay swelling problems, ammonium chloride is used for 5% in aqueous solution. Ammonium chloride is used as an electrolyte in Zinc-Carbon batteries. Ammonium chloride is used in hair shampoo, and cleaning products too. Ammonium chloride is used as glue to attach two plywood. For dyeing, tanning, textile printing, and cotton clustering, ammonium chloride is used in textile and leather industries. In Leclanché cells, Ammonium Chloride was used in aqueous solution as an electrolyte in the start of the 20th century. Ammonium chloride is used in Iron which is used for clothes.

The anhydride is the chemical compound which is obtained, either in principle or in practice, by the elimination of water from any other compound. An example of inorganic anhydrides is given as sulfur trioxide, SO3, which has been derived from the sulfuric acid, and the calcium oxide, CaO, derived from calcium hydroxide. Sulfur trioxide including other oxides produced by the removal of water from acid is often known as acid anhydrides, whereas the ones such as calcium oxide, are produced by a base upon the loss of water are designated as basic anhydrides.

Importance of Anhydride

The most important compound of the organic anhydrides is acetic anhydride, with the chemical formula (CH3CO)2O. It can be prepared industrially in either two ways: and from acetic acid by the reaction with ketene or acetylene or by acetaldehyde‘s atmospheric oxidation in the presence of a metal acetate. Other organic anhydrides are prepared from the carboxylic acids by reaction with ketene, acetic anhydride, isopropenyl acetate or methoxy-acetylene. Also, anhydrides can be produced when acyl halides react with carboxylic acid and pyridine or acetic anhydride.

The organic anhydrides can be used to introduce the acyl group (RCO) in organic synthesis. They react with water to produce carboxylic acids, either with alcohols or phenols to form esters and with ammonia and amines to form amides. Acetic anhydride can be employed in cellulose acetate manufacturing, which is widely used as a base for the magnetic tape and in textile fibre manufacturing. Also, it can be heated with salicylic acid to form the medicinal chemical acetylsalicylic acid (which is called aspirin).

Preparation

Organic acid anhydrides can be prepared in the industry by various means. Mainly, acetic anhydride is produced by the carbonylation of methyl acetate. Maleic anhydride can be prepared by the oxidation of butane or benzene. Laboratory routes emphasize the corresponding acid’s dehydration. The conditions change from acid to acid, but the phosphorus pentoxide remains as a common dehydrating agent:

2 CH3COOH + P4O10 → CH3C(O)OC(O)CH3 + P4O9(OH)2

Mixed anhydrides, which contains the acetyl group can be prepared from ketene:

RCO2H + H2C=C=O → RCO2C(O)CH3

Acid chlorides are also effective precursors:

CH3C(O)Cl + HCO2Na → HCO2COCH3 + NaCl

Reactions

Acid anhydrides are the reactive acyl group source, and the reaction and use of acetic anhydride resemble those of acyl halides. With the protic substrate reactions, they afford similar amounts of the acylated product and the carboxylic acid:

RC(O)OC(O)R + HY → RC(O)Y + RCO2H

For HY = HOR (alcohols), aromatic ring (see Friedel-Crafts acylation), and HNR’2 (ammonia, primary, and secondary amines).

Acid anhydrides tend to be less electrophilic compared to acyl chlorides, and only one acyl group can be transferred per molecule of the acid anhydride, which can lead to a lower efficiency atom. However, the low cost of acetic anhydride makes it a common choice for the acetylation reactions.

Applications and Occurrence of Acid Anhydrides

Acetic anhydride is a primary industrial chemical, which can be widely used in the preparation of acetate esters. For example, cellulose acetate is the one. Maleic anhydride is also the precursor to multiple resins by copolymerization with styrene. And, maleic anhydride is a dienophile in the reaction of Diels-Alder.

Dianhydrides, the molecules containing two acid anhydride functions can be used to synthesize polyimides and at times, polyamides and polyesters. Examples of dianhydrides can be given as 3,3′, 4,4’-benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), 3,3′, 4,4′ – oxydiphthalic dianhydride (ODPA), benzoquinone tetracarboxylic dianhydride, ethylene tetracarboxylic dianhydride, and 4,4′-diphthalic (hexafluoroisopropylidene) anhydride (6FDA). Polyanhydrides are given as a class of polymers characterized by the anhydride bonds, which connect to the repeat units of the polymer backbone chain.

Natural products that contain acid anhydrides have been isolated from the bacteria, fungi, and animals. Some of the examples include cantharidin from the blister beetle species, including the Lytta vesicatoria, tautomycin, and Spanish fly, from the bacterium Streptomyces spiro verticillatus. The maleidride family of the fungal secondary metabolites that possess a wide range of antifungal and antibiotic activity are the alicyclic compounds with the functional groups of maleic anhydride.

Acid Anhydride

A molecule where two acid groups which contain more than one oxygen, bonded to each other, generally having displaced water in the process. (Thus the term “anhydride,” strongly implies an unspecified absence of the water at someplace). The resulting chemical structure can be represented as follows:

(Image to be added soon)

Where R and R₁ would be anything, and in some special cases, the carbon lying next to them can also be something. In other terms, the oxygens are representative and the bonds leading off them are the strict requirements, but everything else can be shown as something else.

In other special cases, the oxygen compounds are also swapped out for sulfurs, but this case is very rare, and the bond structure remains similar in this case.