4-Chloro-4'-fluorobutyrophenone CAS 3874-54-2

It is the core raw material for the synthesis of a variety of psychotropic drugs. Its carbonyl and chlorine atoms can introduce different functional groups through selective reactions to build complex drug molecules.
1. Synthesis of antipsychotic drugs
Haloperidol: As a typical antipsychotic drug, in the synthesis of haloperidol, 4-chlorophenylpiperazine is refluxed in acetonitrile solution under the catalysis of sodium iodide (NaI) and sodium bicarbonate (NaHCO₃) for 22 hours to generate the target product.

This route efficiently constructs the butyrophenone skeleton in the drug molecule through the condensation reaction of carbonyl and amine, with a total yield of 65%-70%.
Lumateperone: A new type of antipsychotic drug, in its synthesis, this substance is used as a starting material, and the chlorine atom on the alkyl chain undergoes a nucleophilic substitution reaction to introduce the piperazine ring structure, and finally constructs a drug molecule with multi-target effects.

2. Development of sedative hypnotic drugs
Droperidol: Used for pre-anesthetic sedation and postoperative nausea and vomiting treatment, its carbonyl and amino groups condense in its synthesis to form an imine intermediate, which is further reduced to obtain the target product. This route avoids the use of highly toxic phosgene in traditional methods and significantly improves process safety.
3. Research on antidepressant drugs
Ciproxifan: A histamine H₃ receptor antagonist. During its synthesis, the substance introduces a cyclopropylmethanol structure through a nucleophilic substitution reaction, and finally obtains a candidate drug with antidepressant activity. The compound showed good pharmacokinetic properties in preclinical studies.

It is a core precursor for the synthesis of fluorophenylbutyric acid derivatives. The chlorine atoms and carbonyl groups in its structure can be introduced into a variety of functional groups through nucleophilic substitution, condensation, reduction and other reactions to construct a library of complex compound.
1. Nucleophilic substitution reaction
Alkyl chain modification: Chlorine atoms can be replaced by nucleophilic reagents such as sodium alcoholate and amines to generate ether or amine derivatives. 

Functionalization of aromatic rings: Through Friedel-Crafts reaction, fluorobenzene rings can undergo alkylation or acylation under Lewis acid catalysis. For example, it reacts with benzene under the catalysis of anhydrous aluminum chloride to generate 1,1-diphenyl-4-fluoro-1-butanone with a yield of 62%.
Synthesis of imine compound: Carbonyl groups condense with amine compound to generate imines, which can be further reduced to obtain secondary or tertiary amines. For example, 4-Chloro-4'-fluorobutyrophenone reacts with n-butylamine to generate N-n-butyl-4'-fluorobenzene imine with a yield of 90%; this intermediate can be reduced to N-n-butyl-4'-fluorobenzene imine by catalytic hydrogenation and is used to synthesize antihistamine drugs.

Construction of β-ketoesters: It undergoes Claisen condensation with diethyl malonate under base catalysis to generate diethyl 4-fluoro-γ-ketopentanoate with a yield of 75%. This compound is a key intermediate for the synthesis of vitamin E derivatives.

3. Reduction reaction
Preparation of alcohol compound: The carbonyl group is reduced to a secondary alcohol by sodium borohydride (NaBH₄) to generate 4-chloro-4'-fluoro-1-phenyl-1-butanol with a yield of 88%. The alcohol compound can be further derivatized by esterification or etherification reaction.

Synthesis of amine compound: The carbonyl group is converted into a methylamine structure by Leuckart reaction or Eschweiler-Clarke methylation to generate N-methyl-4-chloro-4'-fluorobenzbutylamine with a yield of 65%. This compound is a precursor for the synthesis of sympathomimetic drugs.

Its active functional groups make it an ideal tool for material surface modification, introducing functional molecules into the surface of polymers, nanomaterials or biomacromolecules through covalent bonds, giving the material new physical and chemical properties.

1. Polymer functionalization
Biocompatibility modification: On the surface of polylactic acid-co-glycolic acid (PLGA), the carboxyl group is activated by CDI and then reacted with 4-chloro-4'-fluorobutyrophenon to introduce fluorine or chlorine atoms, which significantly reduces the immunogenicity of the material and promotes cell adhesion. For example, the modified PLGA scaffold shows excellent cell compatibility in neural tissue engineering.

Conductive polymer modification: On the surface of polypyrrole (PPy), 4-chloro-4'-fluorobutyrophenon is coupled to the polymer skeleton by CDI to construct a fluorescently labeled conductive material.

When this material is used in a glucose sensor, the detection limit is as low as 0.1μM and it has good anti-interference ability.
2. Nanomaterial surface engineering
Quantum dot modification: Carboxylated CdSe quantum dots are coupled to 4-chloro-4'-fluorobutyrophenon by CDI, and then combined with amino antibodies to construct a fluorescent immunoprobe. For example, for the detection of tumor marker CA125, the sensitivity is 0.1ng/mL, which is 10 times higher than that of traditional methods.

Functionalization of magnetic nanoparticles: On the Fe₃O₄ surface, 4-chloro-4'-fluorophenylbutyric acid is coupled to the end of the polyethylene glycol (PEG) chain through CDI to achieve specific recognition of tumor cells by the targeted drug delivery system. The drug loading of the modified nanoparticles is increased to 25%, and the circulation time in the blood is extended to 24 hours.

Due to its clear structure and high reactivity, it is widely used in organic synthesis methodology research and becomes a model substrate for exploring new reactions and new catalysts.
1. Asymmetric catalysis research
Chiral amine synthesis: Using this substance as a raw material, asymmetric reduction reaction is catalyzed by a chiral catalyst (such as BINOL-phosphoric acid) to generate chiral alcohol compound.

For example, at -20°C, using 10 mol% catalyst and reacting for 24 hours, a chiral product with an ee value > 95% is obtained, which provides an efficient method for synthesizing chiral drugs.
Chiral imine construction: chiral imine intermediates are generated by catalyzing asymmetric condensation reactions with chiral ligands (such as pyridine bisoxazoline). 

3. Combination of single-molecule technology
Single-molecule fluorescence imaging: Fluorescent dyes (such as Cy3) modified with 4-chloro-4'-fluorophenylbutyric acid are coupled to protein molecules through CDI to achieve dynamic tracking at the single-molecule level. For example, in studying protein folding, this technique can capture millisecond-level time resolution data.
Single-molecule force spectroscopy: 4-chloro-4'-fluorobutyrophenone is introduced to the end of the polyethylene glycol chain through CDI to construct a single-molecule force spectroscopy probe. This probe can measure the intermolecular interaction force and is used to study DNA-protein binding or cell adhesion mechanisms.

2. Development of photo-/electrically responsive materials
Photochromic materials: Introducing them into the spiropyran structure, reversible ring-opening-ring-closing conversion is achieved through ultraviolet light irradiation to construct photochromic molecules. This material has potential applications in the fields of optical storage and optical switching.
Electrochromic materials: 4-chloro-4'-fluorophenylbutyric acid is coupled to violacein derivatives through CDI to construct electrochromic molecules. This material can change color under the action of an electric field and is used in smart windows or display devices.

This polarity will promote dipole-dipole interactions between molecules, thereby influencing the packing arrangement of the molecules. Specifically, the molecules may tend to arrange in a head-tail or head-head manner to maximize the interaction energy between molecules and form a more stable crystal structure.

The molecular configuration of 4-Chloro-4'-fluorobutyrophenone, particularly the relative orientation of the benzene ring and the butyrolactone group, has a significant impact on the solid-state packing. If the molecular configuration is relatively planar, intermolecular π-π stacking interactions may enhance the packing stability. However, due to the presence of the butyrolactone group, the molecules may have a certain stereocenter configuration, which will affect the close packing between molecules. In this case, the molecules may adjust their configuration, such as rotation or distortion, to optimize the contact area and interaction force between molecules, thereby achieving more effective packing.

The crystal structure directly reflects the molecular packing mode and plays a decisive role in the solid-state properties of 4-Chloro-4'-fluorobutyrophenone. Different crystal structures can lead to different packing densities, porosities, and physical properties. For instance, some crystal structures may have a higher packing density, resulting in a higher melting point and thermal stability; while others may have a larger porosity, which is beneficial for adsorption or catalytic applications. By adjusting crystallization conditions, such as temperature, solvent, and concentration, the formation of crystal structures can be influenced, thereby optimizing the packing potential in the solid state.

4-Chloro-4'-fluorobutyrophenone's accumulated potential in the solid state is of great significance for its applications in the fields of medicinal chemistry and materials science. In medicinal chemistry, the solid-state properties such as solubility, stability, and bioavailability directly affect the efficacy and safety of drugs. By optimizing the molecular packing arrangement, these properties can be improved, thereby enhancing the quality of the drugs.