Alcohols
Alcohols are organic compounds characterized by the presence of a hydroxyl (-OH) group attached to a carbon atom. They are commonly used as solvents, antiseptics, and in the production of beverages and pharmaceuticals. Alcohols can be classified as primary, secondary, or tertiary based on the number of carbon atoms bonded to the carbon atom bearing the hydroxyl group.
6 Key excerpts on "Alcohols"
eBook - ePub- J Fisher, J.R.P. Arnold, Julie Fisher, John Arnold(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...Section J - Organic Compounds By Chemical Class J1 Alcohols and related compounds DOI: 10.1201/9780203079522-38 Key Notes Alcohol reactions Alcohols may undergo a wide range of reactions. The presence of an oxygen atom with its two lone pairs of electrons means that Alcohols may act as nucleophiles. However, among the most important reactions are those that lead to the loss of water (dehydration reactions), and those that lead to the formation of carbonyl compounds (oxidation reactions). Important Alcohols The simplest alcohol, methanol, is commercially produced in huge quantities. Ethanol is the alcohol referred to when talking about alcoholic beverages. In addition to this, it is used therapeutically as a competitive inhibitor to treat ethylene glycol (a diol) poisoning. More complicated Alcohols have antiseptic (propan-2-ol) and other therapeutic properties. Aromatic Alcohols Benzene-based Alcohols are referred to as phenols. Phenol itself is a well known antiseptic, although today phenol derivatives are more commonly used for this purpose. Phenols are weak acids as the anion formed on deprotonati on of the hydroxyl group is stabilized by resonance. Dehydration and oxidation reactions are generally not possible. Ethers Aliphatic ethers are of limited use as reagents in chemical or biochemical processes. However, they are routinely used as solvents for chemical reactions and as anesthetics. Cyclic derivatives of these compounds such as furans and pyrans (and their saturated derivatives) occur in many carbohydrates. Thiols Thiols are the sulfur derivatives of Alcohols, and display a number of similar properties. Thiols are most noted for their strong and often unpleasant odors. They are readily oxidized to disulfides, and this is particularly important in protein chemistry...
eBook - ePub- Tony Farine, Mark A. Foss(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
...Many, such as saturated fats, contain chains of carbon atoms such as the alkanes and some, such as polyunsaturated fats, contain double bonds such as the alkenes. If you learn about the simpler organic molecules now, you will find it easier later on to understand the structure of more complex molecules found in the body. Some of these large, more complex organic molecules are introduced as nutrients in Chapter 7. Many different organic compounds share chemical and physical properties. For example, most are flammable. Some properties, however, are characteristic of only certain groups. Consider odour for a moment. Methane has no smell; its use as a fuel, therefore, would be problematic, since gas leaks might go undetected were it not for the fact that gas companies add an odour to it. Other organic molecules have characteristic odours. For example, ketones (see later), which smell like pear drops, can be smelled on the breath of poorly controlled diabetic patients who produce ketones in excess. Consequently, smelling ketones on the breath of a patient is an important nursing observation. The distinctive chemical or physical properties of organic compounds exist as a consequence of the possession of certain chemical groups called functional groups. These often contain elements such as oxygen and hydrogen, and sometimes nitrogen too. We shall continue our study of organic molecules by thinking about Alcohols. Alcohols Alcohols are compounds that contain one or more hydroxyl groups (OH) and conform to the general formula RCH 2 OH. In organic chemistry, R stands for either a hydrogen atom or a carbon-atom chain with hydrogen atoms attached. Alcohols are named by adding the suffix –ol to the relevant prefix. Consequently, the simplest alcohol is methanol (CH 3 OH). You might buy methanol in the form of methylated spirits in order to fuel a camping stove or for use as a solvent...
eBook - ePubChemistry
Concepts and Problems, A Self-Teaching Guide
- Richard Post, Chad Snyder, Clifford C. Houk(Authors)
- 2020(Publication Date)
- Jossey-Bass(Publisher)
...The simplest alcohol is methanol, CH 3 –OH. Methanol can be represented the following ways. Naming Alcohols is rather straightforward and is also similar to alkane nomenclature. The number of carbons is drawn from the parent alkane names. The suffix “–ane” is changed to “–ol” to reflect the hydroxyl functional group. Ethanol contains two carbons and the –OH functional group. Below are the different ways to represent ethanol. What is the molecular formula and condensed formula for propanol? Propanol is an alcohol with three carbons. Answer: C 3 H 8 O, CH 3 CH 2 CH 2 OH As the number of carbon atoms in Alcohols increase so does their complexity. The three carbon-containing Alcohols have the molecular formula C 3 H 8 O and can come in the form of two structural isomers. The numbering system shows where the –OH group is attached. Alcohols are usually classified by the number of carbon atoms attached to the C–OH carbon. A primary (1°) alcohol has one carbon bonded to it, a secondary (2°) alcohol has two, and a tertiary (3°) alcohol has three. For each of the following Alcohols circle the carbon atom(s) directly attached to the C–OH carbon atom. Then label the C–OH carbon as primary (1°), secondary (2°), or tertiary (3°). Answer: Draw the line structure for 3-hexanol and state whether it is a primary, secondary, or tertiary alcohol. Answer:, this is a secondary alcohol. Ethers Our next oxygen-containing functional group has the C–O–C connection. These are known as ethers. Ethers have been used in chemical reactions and in medicine. The simplest ether has two methyl groups connected by an oxygen atom. This compound is known as dimethyl ether...
eBook - ePub- Graham Patrick(Author)
- 2004(Publication Date)
- Taylor & Francis(Publisher)
...Functional group transformations to a phenol. M3 Properties of Alcohols and phenols Key Notes Alcohols The carbon and oxygen atoms of the alcohol group are sp 3 hybridized such that the C–O–H bond angle is approximately 109°. Hydrogen bonding means that Alcohols have higher boiling points than comparable alkanes. Alcohols of low molecular weight are soluble in water and can act as weak acids and weak bases. Alcohols are polar. The oxygen atom is a nucleophilic center while the neighboring carbon and hydrogen are weak electrophilic centers. Alcohols will not react with nucleophiles, but will react with strong bases in an acid–base reaction to form an alkoxide ion. An alcohol' s C–O bond can be split if the hydroxyl group is converted into a better leaving group. Phenols Phenols have an OH group directly linked to an aromatic ring. The oxygen is sp 3 hybridized and the aryl carbon is sp 2 hybridized. Phenols are polar compounds which are capable of intermolecular hydrogen bonding such that phenols have higher boiling points than nonphenolic aromatic structures of comparable molecular weight. Hydrogen bonding also permits moderate water solubility and phenols act as weak acids in aqueous solution. Phenols are stronger acids than Alcohols but weaker acids than carboxylic acids. They are soluble as their phenoxide salts in sodium hydroxide solution, but insoluble in sodium hydrogen carbonate solution. Spectroscopic analysis of Alcohols and phenols Alcohols and phenols can be identified by the presence of an O–H stretching absorption in the IR spectrum as well as a D 2 O exchangeable OH signal in the 1 Hnmr spectrum. Further evidence can be obtained from the IR spectrum if absorptions due to O–H bending and C–O stretching are identifiable. In nmr spectra, the chemical shifts of neighboring groups give indirect evidence of an OH group...
- John Brick, John Brick(Authors)
- 2012(Publication Date)
- Routledge(Publisher)
...Chapter 1 Characteristics of Alcohol: Definitions, Chemistry, Measurement, Use, and Abuse Brick, John We begin this textbook with an overview of alcohol, one of the oldest and most widely used psychoactive drugs on earth. In an effort to provide a foundation for the interpretation of terms related to alcohol and its use throughout this text and elsewhere, this introductory chapter will define alcohol both as a chemical and as a drug, explain the scientific notation for reporting alcohol in blood or serum, and present an overview of the use of alcohol: how we currently define alcohol use, abuse, and dependence in American society. What is Alcohol? The term “alcohol” is used to define several types of alcohol, including the three most common: ethyl alcohol (ethanol), methyl alcohol (methanol), and isopropyl alcohol (isopropanol). All Alcohols have a similar chemical structure and contain a hydroxyl group, OH, attached to a saturated carbon molecule. Methyl alcohol, also known as methanol or wood alcohol, is so highly toxic that even small amounts (less than an ounce) may cause retinal damage. Methanol’s toxicity is the result of its metabolism to formaldehyde and then to formic acid, a cellular toxin that is about six times more poisonous than methanol. The accumulation of formic acid produces severe metabolic acidosis and more than 6 to 7 ounces of methanol are lethal for most adults. Isopropyl alcohol, also known as isopropanol or common rubbing alcohol, is also highly toxic. Small amounts, as little as a few ounces, can cause permanent damage to the visual system, and 8 ounces is considered a lethal dose. Some alcoholics may consume methanol or isopropanol, intentionally or unknowingly, and of the three Alcohols with potentially lethal consequences discussed here, methanol and isopropanol are the most dangerous. The alcohol that is the subject of this review and the alcohol consumed as a beverage by most people, is ethanol, a clear, relatively odorless chemical...
eBook - ePubHandbook of Enology, Volume 2
The Chemistry of Wine Stabilization and Treatments
- Pascal Ribéreau-Gayon, Yves Glories, Alain Maujean, Denis Dubourdieu, John Towey(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
...These molecules are present in very small amounts, and the exact proportion depends on the origin of the sugar that was fermented (grapes, beets, and/or sugarcane), as well as on the growing region. A method for controlling the addition of sugar to must (chaptalization) and detecting fraud has been developed on the basis of this property (Martin and Brun, 1987). This method has been officially recognized by the International Organisation of Wine and Vine (OIV). FIGURE 2.1 Structure of ethanol and definition of the alcohol function. Ethanol's affinity for water and its solubility, by forming hydrogen bonds, makes it a powerful dehydrant. This property is useful in flocculating hydrophilic colloids, proteins, and polysaccharides. It also gives ethanol disinfectant properties that are particularly valuable in aging wine. The combination of ethanol and acidity makes it possible to keep wine for a long time without any noticeable spoilage. The addition of ethanol to stabilize certain wines is a long‐standing winemaking tradition (Port, vins doux naturels). However, ethanol is toxic for humans, affecting the nerve cells and liver. Ethanol's solvent properties are also useful for dissolving phenolic compounds from grape skins during red winemaking. This property is involved in solubilizing certain aroma molecules and certainly contributes to the expression of aromas in wine. Ethanol has all the chemical properties of an alcohol function. In particular, it esterifies with tartaric, malic, and lactic acids (Section 2.5.3). Ethyl acetate gives wine an unpleasant odor and is a sign of bacterial spoilage (Section 2.5.1). Ethanol may also react with hydrogen sulfide, produced by fermenting yeast or resulting from the residues of some vineyard treatment products (Section 8.6.3). This substitution reaction generates ethanethiol (Figure 2.2), which has a very unpleasant smell. As this compound is much less volatile than H 2 S, it is more difficult to eliminate...
