Alcohols, Ethers and Thiols
Alcohols, ethers, and thiols are organic compounds characterized by the presence of specific functional groups. Alcohols contain a hydroxyl (-OH) group, ethers have an oxygen atom bonded to two alkyl or aryl groups, and thiols feature a sulfur atom bonded to a hydrogen atom and an alkyl or aryl group. These compounds have diverse applications in organic synthesis, pharmaceuticals, and industrial processes.
5 Key excerpts on "Alcohols, Ethers and Thiols"
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- Graham Patrick(Author)
- 2004(Publication Date)
- Taylor & Francis(Publisher)
...For example, ethanethiol boils at 37°C whereas ethanol boils at 78°C. Low molecular weight thiols are notorious for having disagreeable aromas. Reactivity Thiols are the sulfur equivalent of alcohols (RSH). The sulfur atom is larger and more polarizable than oxygen which means that sulfur compounds as a whole are more powerful nucleophiles than the corresponding oxygen compounds. Thiolate ions (e.g. CH 3 CH 2 S −) are stronger nucleophiles and weaker bases than corresponding alkoxides (CH 3 CH 2 O −). Conversely thiols are stronger acids than corresponding alcohols. The relative size difference between sulfur and oxygen also means that sulfur' s bonding orbitals are more diffuse than oxygen' s bonding orbitals. This results in a poorer bonding interaction between sulfur and hydrogen, than between oxygen and hydrogen. As a result, the S–H bond of thiols is weaker than the O–H bond of alcohols (80 kcal mol −1 vs. 100 kcal mol −1). This in turn means that the S–H bond of thiols is more prone to oxidation than the O–H bond of alcohols. Reactions Thiols are easily oxidized by mild oxidizing agents such as bromine or iodine to give disulfides (Figure 2). Thiols react with base to form thiolate ions which can act as powerful nucleophiles (Section L6 ; Figure 3). Figure 2. Oxidation of thiols. Figure 3. Formation of thiolate ions....
eBook - ePubChemistry
Concepts and Problems, A Self-Teaching Guide
- Richard Post, Chad Snyder, Clifford C. Houk(Authors)
- 2020(Publication Date)
- Jossey-Bass(Publisher)
...The following are not considered aromatic hydrocarbons since there are atoms other than carbon and hydrogen within their structure. However, these compounds contain the aromatic ring structure. Circle the aromatic ring found in the structure of ibuprofen. Answer: Aromatic rings are also found in a variety of natural products. Benzaldehyde (shown below) contributes to the smell of oyster mushrooms. Circle the aromatic ring found in benzaldehyde. Answer: OXYGEN-CONTAINING ORGANIC COMPOUNDS The next class of organic compounds are the ones that contain the oxygen atom as part of their functional group. A functional group is a particular connection of atoms that have unique chemical and physical properties. Functional groups are the reactive portion of a molecule. Alcohols, ethers, ketones, aldehydes, carboxylic acids, and esters all contain oxygen as part of their functional group. Alcohols Alcohols are an important class of organic compounds that are used as solvents, cleaners, and chemicals to make more complicated organic compounds. Common alcohols include isopropyl alcohol and ethanol. Isopropyl alcohol is used in antiseptics and disinfectants. Ethanol is also known as drinking alcohol. When an sp 3 hybridized carbon atom is single-bonded to an –OH group that functional group is known as an alcohol group (aka, a hydroxyl group). The basic structure of the alcohol functional group is C–O–H. However, the carbon atom requires its other connected atoms to fulfill its octet. 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...
eBook - ePub- Katarzyna Staszak, Karolina Wieszczycka, Bartosz Tylkowski, Katarzyna Staszak, Karolina Wieszczycka, Bartosz Tylkowski(Authors)
- 2020(Publication Date)
- De Gruyter(Publisher)
...5 Trends in technology of oxygen containing hydrocarbons: aldehydes, ketones, ethers Katarzyna Materna Institute of Chemical Technology and Engineering, Poznan University of Technology, Poznan, Poland Abstract The structural element of many organic compounds in which the carbon atom combines with the oxygen atom in a double bond is called the carbonyl group. Both atoms forming such a double bond are characterized by hybridization of the sp2 type. Spatially, these two atoms and two other atoms directly related to the carbon atom lie in the same plane. One of the carbon–oxygen bonds is of σ type, formed by two overlapping sp2 orbital bonds, while the other is of π type, realized through the commonalization of non-hybridized electrons from orbital π. The carbonyl group “–C=O” is a common element in the structure of aldehydes and ketones and to a large extent determines their chemical properties. Aldehydes are organic compounds in which the carbonyl group is connected by one single bond to the hydrogen atom and the other to the rest of the hydrocarbon molecule. In aldehydes, the C=O group occurs at the end of the carbon chain; it is connected with a single C–C bond; the fourth bond is saturated with hydrogen atom. Ketones are organic compounds containing a carbonyl group which is combined with two hydrocarbon groups. In ketones, the C=O group occurs within the carbon chain of molecules; the carbon atom of the carbonyl group is secondary. Ethers are organic compounds in which C–O–C bonds are present, where none of the carbon atoms is bound to more than one oxygen atom. Keywords: aldehydes, ketones, ethers, oxidation, dehydrogenation, primary and secondary alcohols, reduction, dehydration, 5.1 Introduction The structural element of many organic compounds in which the carbon atom combines with the oxygen atom in a double bond is called the carbonyl group. Both atoms forming such a double bond are characterized by hybridization of the sp 2 type...
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)
...odors CH 3 −(CH 2) 4 −CH 2 OH 1‐Hexanol 158 0.01 CH 3 −(CH 2) 3 −CHOH−CH 3 2‐Hexanol 138 ? CH 3 −(CH 2) 5 −CH 2 OH 1‐Heptanol 177 Traces CH 3 − (CH 2) 4 − CHOH − CH 3 2‐Heptanol 160 ? CH 3 − (CH 2) 6 − CH 2 OH 1‐Octanol 194 ? CH 3 − (CH 2) 5 − CHOH − CH 3 2‐Octanol[--=PLGO-SEP. ARATOR=--]180 ? CH 3 − (CH 2) 7− CH 2 OH 1‐Nonanol 212 ? CH 3 − (CH 2) 6− CHOH− CH 3 2‐Nonanol ? CH 3 − (CH 2) 8 − CH 2 OH 1‐Decanol 229 ? Φ− CH 2 − CH 2 OH 2‐Phenylethanol 219 0.05 Fermentation alcohol(rose odor) OH −Φ− CH 2 − CH 2 OH Tyrosol CH 3 − (CH 2) 4 − CHOH − CH=CH 2 1‐Octen‐3‐ol Mushroom odor Φ, benzene. ring. FIGURE 2.4 Biosynthesis of higher alcohols, according to Ehrlich. Higher alcohols are found in brandies after distilling and contribute to their specific characters. Distillation techniques have a major impact on their overall concentration. 2.2.3 Miscellaneous Alcohols These molecules originate from grapes and are found in wines. One group consists of C6 alcohols, hexanols and hexenols from plant tissues, giving the herbaceous/grassy aromas so characteristic of wines made from unripe grapes (Volume 1, Sections 11.6.2 and 13.3.4). Another of these compounds is 1‐octen‐3‐ol, with an odor reminiscent of mushrooms. Its presence in wine is due to the action of Botrytis cinerea on grapes. Finally, terpene alcohols, the main components in the distinctive Muscat aroma, are described in full elsewhere (Section 7.2.1). 2.3 Polyols Polyols are characterized by the presence of several hydroxyl radicals in the same linear or cyclic molecule. In general, an accumulation of hydroxyl radicals in a compound raises the boiling point considerably (Table 2.2) due to the large number of hydrogen bonds, as well as increasing its viscosity and anti‐freeze properties. Parallel increases are observed in solubility and sweetness...
