(4-Bromobut-1-yn-1-yl)trimethylsilane: Properties & Lab Use

(4-Bromobut-1-yn-1-yl)trimethylsilane is a bifunctional organosilicon alkyne reagent featuring both a terminal trimethylsilyl-protected triple bond and a primary alkyl bromide, making it a versatile building block for organic synthesis.

CAS-style Molecular Formula

C7H13BrSi

Molecular Weight

205.16 g/mol (approximate; verify against certificate of analysis)

Functional Groups

Terminal TMS-alkyne and primary alkyl bromide

Key Reactivity

Electrophilic alkylation via C–Br bond; nucleophilic alkynylation after TMS deprotection

Storage Recommendation

Store under inert atmosphere, refrigerated (2–8 °C), away from moisture and light

Aladdin SKU

B589910

What Is (4-Bromobut-1-yn-1-yl)trimethylsilane and Why Is It Used?

(4-Bromobut-1-yn-1-yl)trimethylsilane (Aladdin SKU: B589910) is a bifunctional organosilicon reagent that combines two orthogonal reactive handles within a four-carbon chain: a trimethylsilyl (TMS)-protected terminal alkyne at C-1 and a primary alkyl bromide at C-4. This dual functionality makes it particularly attractive as a linker or homologation unit in multi-step synthesis.

The TMS group serves as a protecting group for the terminal alkyne, suppressing unwanted terminal alkyne acidity and facilitating selective transformations. After synthetic elaboration at the C–Br terminus, the TMS group can be removed under mild fluoride or base conditions to reveal a free terminal alkyne for further coupling, such as Sonogashira or Glaser reactions.

The primary alkyl bromide end participates readily in nucleophilic substitution (S_N2), metal-catalyzed cross-coupling, or radical reactions, offering broad compatibility with standard synthetic strategies.

Physical and Chemical Properties

(4-Bromobut-1-yn-1-yl)trimethylsilane is expected to be a colorless to pale yellow liquid at room temperature, consistent with similar low-molecular-weight TMS-alkynes. Key physicochemical characteristics include:

• Molecular Formula: C₇H₁₃BrSi
• Approximate Molecular Weight: ~205.16 g/mol (confirm with certificate of analysis)
• Functional Groups: Internal TMS-alkyne (C≡C–TMS) and primary C–Br
• Solubility: Expected to be soluble in common organic solvents such as THF, DCM, diethyl ether, toluene, and hexanes; insoluble in water
• Stability: Sensitive to moisture and strong bases; the alkyl bromide may undergo elimination under strongly basic conditions

Note: Exact physical constants (boiling point, density, refractive index) should be verified against the product certificate of analysis supplied with each lot.

Handling, Safety, and Storage Guidelines

As with most organobromine and organosilicon reagents, appropriate precautions should be observed when handling (4-Bromobut-1-yn-1-yl)trimethylsilane:

• Personal Protective Equipment: Wear chemical-resistant gloves, safety goggles, and a laboratory coat. Work in a well-ventilated fume hood.
• Inert Atmosphere: Handle and store under dry nitrogen or argon to prevent hydrolysis of the Si–C bond and moisture-promoted decomposition.
• Storage Temperature: Refrigerate at 2–8 °C; do not freeze unless specified on the product label.
• Incompatibilities: Avoid contact with strong oxidizers, strong bases (risk of elimination at the alkyl bromide), and nucleophilic reagents that could react prematurely with the C–Br bond.
• Disposal: Follow your institution's chemical waste regulations for halogenated organic compounds.

Always consult the Safety Data Sheet (SDS) supplied by Aladdin Scientific before use. Specific hazard classifications (GHS pictograms, H-statements) should be verified against the current SDS for lot B589910.

Synthetic Applications and Reaction Protocols

(4-Bromobut-1-yn-1-yl)trimethylsilane serves as a versatile C4 alkyne synthon in several key transformations:

1. Nucleophilic Alkylation (via C–Br): React with organometallic nucleophiles (e.g., Grignard reagents, organolithiums, malonate anions) in an S_N2 fashion to extend the carbon skeleton while retaining the TMS-alkyne handle for downstream elaboration.
2. Transition-Metal-Catalyzed Cross-Coupling: The primary alkyl bromide can participate in Pd- or Ni-catalyzed cross-coupling reactions (e.g., Kumada, Negishi, or Suzuki-Miyaura variants adapted for alkyl halides), enabling C–C bond formation under mild conditions.
3. TMS Deprotection then Alkyne Functionalization: Treatment with K₂CO₃ in MeOH or TBAF in THF cleanly removes the TMS group to give 4-bromobut-1-yne, which can then undergo Sonogashira coupling or copper-catalyzed azide-alkyne cycloaddition (CuAAC) for click chemistry applications.
4. Radical Reactions: Under radical initiation conditions, the C–Br bond can serve as a radical precursor for cyclization or addition cascades.

Specific reaction conditions, temperatures, catalyst loadings, and yields should be optimized empirically. Consult primary literature for precedent reactions with analogous substrates.

Ordering, Specifications, and Quality Assurance

Aladdin Scientific offers (4-Bromobut-1-yn-1-yl)trimethylsilane under SKU B589910. When placing an order or evaluating this reagent, consider the following:

• Purity: The purity grade and specification for each lot are detailed in the Certificate of Analysis (CoA), available upon request or via the Aladdin Scientific website using the lot number.
• Available Pack Sizes: Contact Aladdin Scientific sales or visit the product page for current pack sizes and pricing.
• Quality Checks: Aladdin Scientific performs quality control including purity assessment (typically by GC or NMR) and identity confirmation (by NMR or MS) before release.
• Lead Time and Shipping: This reagent should be shipped with appropriate cold-chain packaging. Confirm lead time and shipping conditions with Aladdin Scientific at the time of ordering.
• Custom Quantities: For bulk or custom quantities, contact Aladdin Scientific's technical sales team directly.

For procurement, reference the internal catalog code BD250205 if required by your institution's purchasing system.

Frequently asked questions

What is the difference between (4-Bromobut-1-yn-1-yl)trimethylsilane and 4-bromobut-1-yne?

(4-Bromobut-1-yn-1-yl)trimethylsilane is the TMS-protected form of 4-bromobut-1-yne. The TMS group at the alkyne terminus protects it from undesired deprotonation and side reactions, improving handling stability. Removal of the TMS group (e.g., with K2CO3/MeOH or TBAF/THF) regenerates the free terminal alkyne, 4-bromobut-1-yne, for further synthetic use.

How should I deprotect the TMS group without affecting the alkyl bromide?

Mild fluoride sources such as TBAF in THF, or potassium carbonate in methanol at room temperature, are standard conditions for selective TMS removal from alkynes. These conditions are generally mild enough to leave the primary alkyl bromide intact. However, reaction time and equivalents should be carefully controlled, and the outcome should be verified analytically for each specific substrate context.

Is (4-Bromobut-1-yn-1-yl)trimethylsilane suitable for Sonogashira coupling?

Not directly in its TMS-protected form, since the alkyne terminus is silylated and not a free terminal alkyne. However, after TMS deprotection to give 4-bromobut-1-yne, the resulting terminal alkyne can participate in Sonogashira coupling with aryl or vinyl halides. Alternatively, the primary alkyl bromide terminus may participate in Pd/Cu-catalyzed alkylative cross-coupling under appropriate conditions, though alkyl halides are generally less reactive than aryl halides in Sonogashira protocols.

What solvents are recommended for reactions using this reagent?

Common dry organic solvents such as THF, diethyl ether, DCM, DMF, and toluene are typically suitable, depending on the specific transformation. Since the reagent is sensitive to moisture, all solvents should be anhydrous. Protic solvents such as water or alcohols should be avoided unless the reaction is specifically designed to tolerate or exploit them.

How do I confirm the identity and purity of the received material?

Request the Certificate of Analysis (CoA) from Aladdin Scientific for your specific lot number (B589910). Identity can be confirmed by 1H NMR (characteristic TMS singlet ~0.15 ppm, alkynyl CH2 signals, and CH2Br signals) and by GC or GC-MS. Purity is typically assessed by GC with a flame ionization detector. Compare all data against the specification limits stated on the CoA.

References

1. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 4th ed.; Wiley: New York, 2007. (TMS protection of alkynes, Chapter on C–C bond-forming reactions)
2. Sonogashira, K. Development of Pd–Cu catalyzed cross-coupling of terminal acetylenes with sp2-carbon halides. J. Organomet. Chem. 2002, 653, 46–49. doi:10.1016/S0022-328X(02)01158-0
3. Aladdin Scientific Product Page: (4-Bromobut-1-yn-1-yl)trimethylsilane, SKU B589910, Internal ref. BD250205.

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