Dichloro[2,2]paracyclophane
[CAS# 28804-46-8]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic hydrocarbon reagent
• Name: Dichloro[2,2]paracyclophane
• Synonyms: 5,11-Dichlorotricyclo[8.2.2.24,7]hexadeca-4,6,10,12,13,15-hexaene; 5,11-Dichlorotricyclo[8.2.2.24,7]hexadeca-4,6,10,12,13,15-hexaene; 6,12-Dichlorobis(p-xylylene); Dichlorodi-p-xylylene
• Molecular Formula: C₁₆H₁₄Cl₂
• Molecular Weight: 277.19
• CAS Registry Number: 28804-46-8 (10366-05-9)
• EC Number: 249-236-8
• SMILES: C1C(C2=CC=C(CC(C3=CC=C1C=C3)Cl)C=C2)Cl

Properties

• Solubility: Insoluble (4.2E^-5 g/L) (25 °C), Calc.^*
• Density: 1.229±0.06 g/cm³ (20 °C 760 Torr), Calc.^*
• Melting point: 165-167 °C
• Index of Refraction: 1.621, Calc.^*
• Boiling Point: 398.0±42.0 °C (760 mmHg), Calc.^*
• Flash Point: 187.8±21.4 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07;GHS08 Warning
• Risk Statements: H302-H315-H317-H319-H335-H373
• Safety Statements: P260-P261-P264-P264+P265-P270-P271-P272-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P333+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Skin sensitization	Skin Sens.	1B	H317
Specific target organ toxicity - repeated exposure	STOT RE	2	H373

Discovery and Applications

Dichloro[2,2]paracyclophane is a chemical compound belonging to the class of paracyclophanes, characterized by two benzene rings linked by a pair of ethylene bridges. The dichloro substitution on the benzene rings adds unique chemical properties to this compound, making it an important precursor in organic synthesis, particularly in the field of polymer chemistry. The discovery and development of dichloro[2,2]paracyclophane have been instrumental in advancing applications in electronics, coatings, and material science.

Paracyclophanes were first synthesized in the mid-20th century by chemists investigating compounds with unusual three-dimensional ring structures. These molecules exhibit strained geometries due to their fused ring systems, which contribute to their distinct reactivity and stability. Dichloro[2,2]paracyclophane was later developed as a modified version, where chlorine atoms replaced hydrogen atoms at the para positions of the benzene rings. This substitution enhances the compound's reactivity, particularly in processes like vapor-phase deposition, which has been fundamental in producing specialized polymers.

One of the primary applications of dichloro[2,2]paracyclophane is in the chemical vapor deposition (CVD) process, specifically in the production of poly(p-xylylene), better known as Parylene polymers. During CVD, dichloro[2,2]paracyclophane is thermally cracked into reactive monomers, which polymerize on various substrates to form thin, uniform, and highly durable films. These films are widely used as protective coatings in electronic devices, such as circuit boards and sensors, where their resistance to moisture, chemicals, and electrical interference is crucial.

Dichloro[2,2]paracyclophane plays a critical role in producing Parylene C, one of the most commercially significant Parylene polymers. Parylene C, derived from dichloro[2,2]paracyclophane, is known for its excellent barrier properties, making it suitable for protecting sensitive electronics in harsh environments, including aerospace and automotive applications. The protective layer is highly conformal, meaning it can coat intricate and irregular surfaces with uniform thickness, ensuring comprehensive protection.

In addition to its use in electronics, dichloro[2,2]paracyclophane has significant applications in the biomedical field. Parylene C coatings are biocompatible, making them ideal for medical devices that come into direct contact with biological tissues. Examples include coatings for pacemakers, catheters, and surgical instruments. The protective films ensure that these devices remain functional while reducing the risk of corrosion, contamination, or interaction with bodily fluids.

Dichloro[2,2]paracyclophane is also used in nanotechnology and microelectromechanical systems (MEMS) due to the precision and control it offers in thin-film deposition. In MEMS, where miniaturization and reliability are key, Parylene C coatings derived from this compound are essential for improving device performance and extending their operational life. Additionally, its low dielectric constant makes it a valuable material in optical and electronic components that require insulation without interfering with signal transmission.

Research into dichloro[2,2]paracyclophane continues, with ongoing studies exploring its potential in advanced material applications, such as flexible electronics, wearable technology, and bioelectronics. The compound’s ability to form stable, protective layers on a variety of surfaces positions it as a versatile and essential building block in cutting-edge material science.

References

2024. Plasma Deposition of Parylene-like Films with Chemical Functional Groups for Immunoassays. ACS Applied Materials & Interfaces.
DOI: 10.1021/acsami.4c13474

2024. Parylene C Coating Efficacy Studies: Enhancing Biocompatibility of 3D Printed Polyurethane Parts for Biopharmaceutical and CGT Applications. ACS Applied Bio Materials.
DOI: 10.1021/acsabm.4c00561

2024. Multifunctional Nanomesh Enables Cellular‐Resolution, Elastic Neuroelectronics. Advanced Materials.
DOI: 10.1002/adma.202403141