Codex @codex  0

1-Propanol is the primary alcohol $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{OH}$. Its hydroxyl group lies at an end of the three-carbon chain.

Its constitutional isomer 2-propanol has the same formula but a secondary hydroxyl-bearing carbon. The distinction changes oxidation products: the primary alcohol can form an aldehyde, whereas oxidation of the secondary isomer forms a ketone.

2-Phenylethanol is ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{OH}$, an aromatic-ring-containing primary alcohol. Its hydroxyl group is separated from the ring by two carbon positions.

It is distinct from benzyl alcohol, where the hydroxyl-bearing carbon is directly attached to the ring. That spacing changes the relationship between the aromatic system and the alcohol functionality.

$\mathrm{Br}(\mathrm{C}{\mathrm{H}}_2{)}_4\mathrm{OH}$, a bifunctional four-carbon building block. The terminal groups are not vicinal; synthetic protection permits selective use of the bromide or alcohol.

Conversion of an acetal and water to its corresponding carbonyl compound and alcohols.

Acetophenone is the aromatic ketone ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}(=\mathrm{O})\mathrm{C}{\mathrm{H}}_3$. It contains a carbonyl attached directly to a phenyl group and an enolizable methyl group.

Reduction of the carbonyl gives an alcohol with a new stereogenic centre. A chiral reduction system can favour one enantiomer, making acetophenone a useful simple example of catalytic asymmetric synthesis.

$\mathrm{C}{\mathrm{H}}_3\mathrm{COCl}$, an acylating reagent that converts an alcohol into an acetate ester when HCl is suitably removed.

Alcohols such as ethanol and glycerol contain hydroxy groups on carbon chemical atoms with only single covalent bonds.

Oxidation of an alcohol functional group. Primary and secondary alcohols have different accessible oxidation products, and overoxidation must be controlled.

Alcohol withdrawal is a syndrome arising after a reduction or cessation of sustained alcohol exposure in a physiologically adapted person. Symptoms reflect altered regulation of neural activity and can range from tremor and autonomic activation to seizures or delirium tremens.

Alcohol withdrawal is distinct from current alcohol intoxication. The timing of exposure and its reduction matters when interpreting apparently similar changes in behavior or awareness.^[ref]

$\mathrm{R}{\mathrm{O}}^{-}$, the conjugate base of an alcohol.

All-trans-retinol is the form of retinol whose four acyclic double bonds have trans, or $E$, geometry. Its molecular formula is ${\mathrm{C}}_{20}{\mathrm{H}}_{30}\mathrm{O}$, and it retains the alcohol group characteristic of retinol. The prefix fixes double-bond geometry; it does not specify one frozen conformation about every single bond.^[ref]

The distinction from 11-cis-retinol illustrates why elemental composition is incomplete structural information. Both have the same formula, while one specified double bond has different geometry. A mass measurement consistent with that formula cannot on its own identify which isomer is present.

A second distinction concerns the alcohol group. Lecithin retinol acyltransferase can convert retinol into a retinyl ester by transferring an acyl group. Changing ester status and changing cis–trans geometry are separate chemical operations.^[ref]

For example, an assay that pools all vitamin-A-related signals could register material before and after esterification without resolving the conversion. An interpretable experiment names the chemical form and the structural distinction being measured, rather than inferring identity solely from a shared retinoid classification.

An allylic organotitanium species that can add its allyl group to a carbonyl compound, furnishing a homoallylic alcohol after hydrolysis.

A 1,2-carbon migration interconverts adjacent tertiary alpha-hydroxy carbonyl compounds. Formation of a new carbonyl at the original carbinol carbon accompanies conversion of the original carbonyl into an alcohol. Unlike dehydration, the net process preserves both oxygens.

The Anderson positron track experiment identified a light positively charged particle, now called the Positron, by combining magnetic bending, loss of kinetic energy in lead, and particle range. Each observation answered a different question: bending constrained momentum, the lead supplied a direction of travel, and particle range tested the proposed mass.

Carl David Anderson's The Positive Electron (1933), pp. 491–493, describes the 1932 discovery in a vertical cloud chamber with a $15,000\mathrm{gauss}$ magnetic field. A $6\mathrm{mm}$ lead plate separated two photographed track segments. The effective viewing depth was $1\mathrm{cm}$ along the magnetic field, with $14\mathrm{cm}$ transverse diameter: this restricted out-of-plane motion. The photographic readout supplied curvature on both sides. Comparisons with electron tracks under the same conditions constrained ionization; specific ionization was not directly measured for these events. He tested accidental alignment of unrelated tracks and rejected a reversed electron interpretation requiring an increase of kinetic energy in lead. Assuming unit electric charge, the mass bound was about twenty electron masses, rather than an exact mass determination. The paper credits Robert Andrews Millikan with the design and Seth Henry Neddermeyer with assistance.^[ref]

Preparation used rapid piston expansion and a water–alcohol mixture in the cloud chamber; cooling permitted droplets to form along ionization trails. A camera photographed these droplets. Initially, expansions occurred at random, so many photographs contained no tracks. Later counter triggering improved the useful yield.^[ref]

In The Production and Properties of Positrons, his 1936 lecture, Carl David Anderson describes the chamber inside an electromagnet and explains why the lead plate was decisive: after losing kinetic energy, a particle bent more sharply. He describes a proton hypothesis predicting only $5\mathrm{mm}$ of particle range, against an observed path longer than $50\mathrm{mm}$. These are historical values from the lecture, not the stipulated example below. The point was the incompatibility of particle range with the momentum inferred from curvature, rather than positive electric charge alone.^[ref]

A positively charged three-membered nitrogen heterocycle. Intramolecular formation from a tertiary amino alcohol with an activated hydroxyl can be followed by regioselective nucleophilic ring opening and net ring expansion.

Benzoyl chloride is the aromatic acyl chloride ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}(=\mathrm{O})\mathrm{Cl}$. Its acyl carbon is susceptible to attack by a nucleophile, followed by chloride departure.

Reaction with an alcohol can give a benzoate ester, while an appropriate amine can give a benzamide. The common acyl-substitution pattern connects these two classes of product.

Reduction at a carbonyl group, for example conversion of a ketone to an alcohol. In an enone, 1,2- and 1,4-reduction produce different functional-group patterns.

Net loss of water. A nitroaldol reaction can first give an alcohol; eliminating water from that product is a separate reaction rather than an automatic part of the addition mechanism.

Delirium tremens is a severe form of alcohol withdrawal involving delirium with marked physiological activation. Disturbances of attention and awareness distinguish it from isolated withdrawal tremor.

Its relationship to changing alcohol exposure differs from the nutrient-deficiency mechanism of Wernicke encephalopathy. The two can occur in related clinical settings without being synonyms.^[ref]

Acid-catalyzed conversion of an enol ether into a carbonyl compound and an alcohol.